阅读说明：本技术 电致吸收光调变器与激光二极管的整合结构 (Integrated structure of electro-absorption light modulator and laser diode ) 是由 颜胜宏 于 2019-08-06 设计创作，主要内容包括：一种电致吸收光调变器与激光二极管的整合结构,包括一半导体基板以及分别形成于半导体基板的一后端以及一前端之上的一激光二极管以及一电致吸收光调变器。其中激光二极管具有一横向磁场偏振模态激光共振腔,供激发一横向磁场偏振模态激光。电致吸收光调变器包括一下半导体层、形成于下半导体层之上的一主动层、以及形成于主动层之上的一上半导体层。主动层包括多个势垒层以及多个量子阱层,多个量子阱层所具有的一量子阱层总层数加一等于多个势垒层所具有的一势垒层总层数,主动层由多个势垒层以及多个量子阱层交替堆迭而成,使得每一所述多个量子阱层之上以及之下分别为多个势垒层的其中之一以及其中之另一。其中至少一层的多个量子阱层包括相对于半导体基板具有拉伸应变的材料,藉此提高电致吸收光调变器对激光二极管所激发出的横向磁场偏振模态激光的一消光比。(An integrated structure of an electro-absorption light modulator and a laser diode comprises a semiconductor substrate, and a laser diode and an electro-absorption light modulator which are respectively formed on the rear end and the front end of the semiconductor substrate. The laser diode has a transverse magnetic field polarization mode laser resonant cavity for exciting a transverse magnetic field polarization mode laser. The electro-absorption light modulator includes a lower semiconductor layer, an active layer formed over the lower semiconductor layer, and an upper semiconductor layer formed over the active layer. The active layer comprises a plurality of barrier layers and a plurality of quantum well layers, the total number of the quantum well layers is equal to the total number of the barrier layers, and the active layer is formed by alternately stacking the barrier layers and the quantum well layers, so that one of the barrier layers and the other of the barrier layers are respectively arranged above and below each quantum well layer. At least one of the quantum well layers comprises a material having tensile strain relative to the semiconductor substrate, thereby increasing an extinction ratio of the electro-absorption optical modulator to transverse magnetic field polarization mode laser light excited by the laser diode.)

1. An integrated structure of an electro-absorption light modulator and a laser diode, comprising:

a semiconductor substrate;

a laser diode formed on a rear end of the semiconductor substrate, wherein the laser diode has a transverse magnetic field polarization mode laser resonant cavity for exciting a transverse magnetic field polarization mode laser; and

an electro-absorption light modulator formed on a front end of the semiconductor substrate, wherein the electro-absorption light modulator comprises:

a lower semiconductor layer formed on the front end of the semiconductor substrate;

an active layer formed on the lower semiconductor layer, wherein the active layer comprises:

a plurality of barrier layers; and

a plurality of quantum well layers, wherein the plurality of quantum well layers has a total number of quantum well layers,

the active layer is formed by alternately stacking the barrier layers and the quantum well layers; and

an upper semiconductor layer formed on the active layer;

wherein at least one of the quantum well layers comprises a material having a tensile strain relative to the semiconductor substrate, thereby increasing an extinction ratio of the transverse magnetic polarization mode laser excited by the laser diode by the electro-absorption light modulator.

2. The integrated electro-absorption light modulator and laser diode structure of claim 1 wherein said at least one quantum well layer has a tensile strain rate of between-0.1% and-2% relative to said semiconductor substrate.

3. The integrated structure of an electro-absorption light modulator and laser diode of claim 1 wherein the plurality of quantum well layers have a total stress strain rate relative to the semiconductor substrate of less than 0%.

4. The integrated electro-absorption light modulator and laser diode structure of claim 3 wherein the total stress-strain rate divided by the total number of quantum well layers is between-0.1% and-2%.

5. The integrated structure of an electro-absorption light modulator and laser diode of claim 1 wherein each of said plurality of quantum well layers comprises a material having a tensile strain relative to said semiconductor substrate.

6. The integrated structure of an electro-absorption light modulator and laser diode as claimed in claim 5, wherein each of said plurality of quantum well layers has a tensile strain rate of between-0.1% and-2% with respect to said semiconductor substrate.

7. The integrated structure of an electro-absorption light modulator and laser diode of claim 5 wherein the plurality of quantum well layers have a total stress strain rate relative to the semiconductor substrate of less than 0%.

8. The integrated electro-absorption light modulator and laser diode structure of claim 7 wherein the total stress-strain rate divided by the total number of quantum well layers is between-0.1% and-2%.

9. The integrated electro-absorption optical modulator and laser diode structure of claim 1 wherein the plurality of quantum well layers of a tensile strained quantum well layer number comprise material having tensile strain relative to the semiconductor substrate, and the plurality of quantum well layers of a compressive strained quantum well layer number comprise material having compressive strain relative to the semiconductor substrate, wherein the tensile strained quantum well layer number is greater than the compressive strained quantum well layer number.

10. The integrated electro-absorption light modulator and laser diode structure of claim 9 wherein the plurality of quantum well layers per tensile-strained quantum well layer number have a tensile strain rate of between-0.1% and-2% relative to the semiconductor substrate.

11. The integrated structure of an electro-absorption light modulator and laser diode of claim 10 wherein the plurality of quantum well layers per compressively strained quantum well layer number have a compressive strain rate greater than or equal to 0.1% and less than or equal to 2% relative to the semiconductor substrate.

12. The integrated structure of an electro-absorption optical modulator and laser diode as claimed in claim 9, wherein a total tensile strain rate is a sum of tensile strain rates of the quantum well layers with respect to the semiconductor substrate and a total compressive strain rate is a sum of compressive strain rates of the quantum well layers with respect to the semiconductor substrate, wherein a total stress strain rate is a sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%.

13. The integrated structure of an electro-absorption light modulator and laser diode as claimed in claim 9, wherein a total tensile strain rate is a sum of tensile strain rates of the quantum well layers with respect to the semiconductor substrate, and a total compressive strain rate is a sum of compressive strain rates of the quantum well layers with respect to the semiconductor substrate, wherein a total stress strain rate is a sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate divided by the total number of quantum well layers is between-0.1% and-2%.

14. The integrated electro-absorption light modulator and laser diode structure as claimed in claim 1, wherein the plurality of quantum well layers of a tensile strained quantum well layer number comprise material having tensile strain with respect to the semiconductor substrate, the plurality of quantum well layers of a compressive strained quantum well layer number comprise material having compressive strain with respect to the semiconductor substrate, wherein a total tensile strain rate is a sum of tensile strain rates of the plurality of quantum well layers with respect to the semiconductor substrate for the number of tensile strained quantum well layers, a total compressive strain rate is a sum of compressive strain rates of the plurality of quantum well layers with respect to the semiconductor substrate of the number of compressively strained quantum well layers, wherein a total stress strain rate is the sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%.

15. The integrated electro-absorption light modulator and laser diode structure of claim 14 wherein the plurality of quantum well layers per tensile-strained quantum well layer number have a tensile strain rate of between-0.1% and-2% relative to the semiconductor substrate.

16. The integrated structure of an electro-absorption light modulator and laser diode of claim 15 wherein the plurality of quantum well layers per compressively strained quantum well layer number have a compressive strain rate greater than or equal to 0.1% and less than or equal to 2% relative to the semiconductor substrate.

17. The integrated electro-absorption light modulator and laser diode structure of claim 14 wherein the total stress-strain ratio divided by the total number of quantum well layers is between-0.1% and-2%.

18. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein each of said plurality of barrier layers comprises a material having a compressive strain with respect to said semiconductor substrate.

19. The integrated electro-absorption light modulator and laser diode structure of claim 18 wherein each of said plurality of barrier layers has a compressive strain rate greater than or equal to 0.1% and less than or equal to 2% relative to said semiconductor substrate.

20. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein each of said plurality of barrier layers has a thickness greater than or equal to 1nm and less than or equal to 15 nm.

21. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein each of said plurality of quantum well layers has a thickness greater than or equal to 3nm and less than or equal to 15 nm.

22. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein the total number of quantum well layers is greater than or equal to 3 and less than or equal to 20.

23. The integrated electro-absorption light modulator and laser diode structure of any one of claims 1 to 17 wherein each of said plurality of quantum well layers has a quantum well layer energy bandgap that is less than a barrier layer energy bandgap of each of said plurality of barrier layers.

24. The integrated electro-absorption light modulator and laser diode structure as claimed in any one of claims 1 to 17 wherein the material comprising each of said plurality of quantum well layers comprises one selected from the group consisting of: indium gallium arsenide phosphide, and indium gallium aluminum arsenide.

25. The integrated electro-absorption light modulator and laser diode structure of claim 24 wherein the material forming each of said plurality of quantum well layers comprises indium gallium arsenide phosphide and the material forming each of said plurality of barrier layers comprises indium gallium arsenide phosphide.

26. The integrated electro-absorption light modulator and laser diode structure of claim 24 wherein the material forming each of said plurality of quantum well layers comprises indium gallium aluminum arsenide and the material forming each of said plurality of barrier layers comprises indium gallium aluminum arsenide.

27. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein the semiconductor substrate is made of a material comprising indium phosphide.

28. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein the laser diode is selected from one of the following groups: a distributed feedback laser and a distributed Bragg reflector laser.

29. The integrated structure of an electro-absorption light modulator and laser diode as claimed in any one of claims 1 to 17, wherein a wavelength of the transverse magnetic field polarization mode laser is greater than or equal to 1.0 μm and less than or equal to 1.6 μm.

30. The integrated electro-absorption optical modulator and laser diode structure as claimed in any one of claims 1 to 17, wherein the total number of quantum well layers plus one is equal to the total number of barrier layers of the plurality of barrier layers, and each of the quantum well layers is adjacent to one of the barrier layers and the other of the barrier layers above and below the quantum well layers.

31. The integrated electro-absorption optical modulator and laser diode structure as claimed in any one of claims 1 to 17, wherein said plurality of barrier layers have a total number of barrier layers that is equal to the total number of quantum well layers, and each of said plurality of barrier layers is adjacent to one of said plurality of quantum well layers and another of said plurality of barrier layers above and below.

32. The integrated electro-absorption light modulator and laser diode structure as claimed in any one of claims 1 to 17, wherein the total number of quantum well layers is equal to a total number of barrier layers of said plurality of barrier layers, one of said plurality of quantum well layers is adjacent to said lower semiconductor layer, and one of said plurality of barrier layers is adjacent to said upper semiconductor layer.

33. The integrated electro-absorption light modulator and laser diode structure as claimed in any one of claims 1 to 17, wherein the total number of quantum well layers is equal to a total number of barrier layers of said plurality of barrier layers, one of said plurality of barrier layers is adjacent to said lower semiconductor layer, and one of said plurality of quantum well layers is adjacent to said upper semiconductor layer.

Technical Field

The present invention relates to an integrated structure of an external light modulator and a laser diode, and more particularly, to an integrated structure of an electro-absorption light modulator and a laser diode.

Background

FIG. 2A is a cross-sectional view of an embodiment of an integrated structure of an electro-absorption light modulator and a laser diode according to the prior art.FIG. 2B is a cross-sectional view of the electro-absorption light modulator of FIG. 2A. The prior art integrated structure 9 of an electro-absorption light modulator and a laser diode comprises a semiconductor substrate 92, a laser diode 91 and an electro-absorption light modulator 90. Wherein the laser diode 91 is formed on a back end 97 of the semiconductor substrate 92; the electro-absorption light modulator 90 is formed on a front end 96 of the semiconductor substrate 92. Wherein the Laser diode 91 is a Distributed Feedback Laser (DFB Laser), the Laser diode 91 has a Laser cavity (not shown), and a quantum well layer (not shown) of the Laser cavity includes a material having Compressive Strain (Compressive Strain) relative to the semiconductor substrate 92, such that the Laser cavity of the Laser diode 91 forms a Transverse Electric field Polarization Mode (TE Mode) Laser cavity. And the transverse electric field polarization mode laser cavity of the laser diode 91 is used for exciting a transverse electric field polarization mode laser. The electro-absorption light modulator 90 includes a lower semiconductor layer 93, an active layer 94 and an upper semiconductor layer 95. The lower semiconductor layer 93 is formed over the front end 96 of the semiconductor substrate 92; an active layer 94 is formed on the lower semiconductor layer 93; an upper semiconductor layer 95 is formed over the active layer 94. Wherein the active layer 94 includes a plurality of barrier layers 99 and a plurality of quantum well layers 98. The total number of barrier layers 99 is one more than the total number of quantum well layers 98. The active layer 94 is formed by alternately stacking a plurality of barrier layers 99 and a plurality of quantum well layers 98, such that one barrier layer 99 is disposed above and below any one quantum well layer 98, and the bottommost layer of the active layer 94 is a barrier layer 99, and the topmost layer of the active layer 94 is a barrier layer 99. Wherein the material constituting the semiconductor substrate 92 includes indium phosphide (InP). The material comprising the quantum well layers 98 comprises indium gallium arsenide phosphide (InGaAsP), wherein each quantum well layer 98 comprises a material that is compressively strained relative to the semiconductor substrate 92 (i.e., the material comprising the quantum well layers 98 has a larger lattice constant than the material comprising the semiconductor substrate 92) with a compressive strain rate that is one quantum well layer compressive strain rate. The material constituting the barrier layers 99 includes indium gallium arsenide phosphide, wherein each of the barrier layers 99 includes a material opposite to that of the barrier layer 99The semiconductor substrate 92 is of a compressively strained material (i.e., the material comprising the barrier layer 99 has a larger lattice constant than the material comprising the semiconductor substrate 92) with a compressive strain rate of the barrier layer that is greater than the compressive strain rate of the quantum well layer (i.e., the material comprising the barrier layer 99 has a larger lattice constant than the material comprising the quantum well layer 98). Wherein each quantum well layer 98 has an energy band gap that is less than an energy band gap of each barrier layer 99. Due to the compressive strain experienced by the quantum well layer 98, the valence band of the quantum well is separated into a Heavy Hole sub-band (Heavy Hole sub-band) at the top of the valence band and a Light Hole sub-band (Light Hole sub-band) at the bottom of the valence band. Thus, the Energy required to transition from the Lowest Energy state Electron sub-band (Lowest Energy Electron sub-band) to the Lowest Energy state Heavy hole sub-band (Lowest Energy Heavy hole sub-band) is less than the Energy required to transition from the Lowest Energy state Electron sub-band to the Lowest Energy state Light hole sub-band (Lowest Energy Light hole sub-band). This facilitates the transition from the lowest energy state electron sub-band to the lowest energy state heavy hole sub-band (the transition occurs when the energy of the incident laser light is greater than the energy required for the transition from the lowest energy state electron sub-band to the lowest energy state heavy hole sub-band). When transverse electric field polarization mode (TE mode) laser light excited by the transverse electric field polarization mode laser resonator of the laser diode 91 passes through the electro-absorption light modulator 90, the absorption coefficient α of the electro-absorption light modulator 90_TEComprises the following steps:

wherein alpha is_LHIs the absorption coefficient of light holes, and alpha_HHThe absorption coefficient of heavy holes is shown. Thus, when transverse electric field polarization mode laser light passes through the electro-absorption optical modulator 90, the quantum well layer 98 of the electro-absorption optical modulator 90 formed of a material having a compressive strain relative to the semiconductor substrate 92 is more predominantly generated from the lowest energy state electron sub-band to the lowest energy state electron sub-bandThe transition of the state heavy hole energy band has higher absorptivity for transverse electric field polarization mode laser. The modulation principle of the electro-absorption optical modulator 90 is to use a plurality of Quantum well layers 98 as the light absorption layer and to use the Quantum Confined Stark Effect (QCSE) for modulation. When the transverse electric field polarization mode laser light excited by the laser diode 91 is conducted into the electro-absorption light modulator 90 by the laser diode 91, an external electric field (e.g., a reverse bias voltage) is applied to the electro-absorption light modulator 90, so that the absorption coefficient of the electro-absorption light modulator 90 is changed, and an Extinction Ratio (Extinction Ratio) of the transverse electric field polarization mode laser light excited by the laser diode 91 by the electro-absorption light modulator 90 is increased. By controlling the magnitude of the applied electric field applied to the electro-absorption optical modulator 90, the extinction ratio of the transverse electric field polarization mode laser passing through the electro-absorption optical modulator 90 can be modulated.

The integrated structure 9 of the prior art electro-absorption optical modulator and laser diode excites the lateral electric field polarization mode laser cavity of the laser diode 91 (the quantum well layer (not shown) of the lateral electric field polarization mode laser cavity is made of a material having compressive strain with respect to the semiconductor substrate 92) to emit lateral electric field polarization mode laser light, which is modulated by the electro-absorption optical modulator 90 (the quantum well layer 98 of the electro-absorption optical modulator 90 is made of a material having compressive strain with respect to the semiconductor substrate 92). The prior art integrated structure 9 of an electro-absorption optical modulator and a laser diode adjusts the compressive strain of the quantum well layer 98 relative to the semiconductor substrate 92 by selecting the material of the quantum well layer 98, so as to reduce the energy required for the transition from the lowest energy state electron sub-band to the lowest energy state heavy hole sub-band, thereby increasing the extinction ratio, which is still not satisfactory.

In view of the above, the inventor has developed a design with simple assembly, which can avoid the above disadvantages, is convenient to install, and has the advantage of low cost, so as to take account of both flexibility and economy.

Disclosure of Invention

The technical problem to be solved by the present invention is how to increase the extinction ratio of the electro-absorption optical modulator to the laser light excited by the laser diode in the integrated structure of the electro-absorption optical modulator and the laser diode.

To solve the above-mentioned problems and achieve the desired effect, the present invention provides an integrated structure of an electro-absorption light modulator and a laser diode, which comprises a semiconductor substrate, a laser diode and an electro-absorption light modulator. The laser diode is formed on a rear end of the semiconductor substrate, wherein the laser diode has a Transverse Magnetic Polarization Mode (TM Mode) laser cavity for exciting a Transverse Magnetic Polarization Mode laser. The electro-absorption light modulator is formed on a front end of the semiconductor substrate. The electro-absorption light modulator includes a lower semiconductor layer, an active layer and an upper semiconductor layer. The lower semiconductor layer is formed on the front end of the semiconductor substrate. The active layer is formed on the lower semiconductor layer. An upper semiconductor layer is formed on the active layer. The active layer includes a plurality of barrier layers and a plurality of quantum well layers. The multiple quantum well layers have a total number of quantum well layers, and the active layer is formed by alternately stacking multiple barrier layers and multiple quantum well layers. At least one of the quantum well layers comprises a material having tensile strain relative to the semiconductor substrate, thereby increasing an Extinction Ratio (Extinction Ratio) of the electro-absorption optical modulator to transverse magnetic field polarization mode laser excited by the laser diode.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode, wherein the quantum well layers of at least one layer have a tensile strain rate between-0.1% and-2% with respect to the semiconductor substrate.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode further comprises a plurality of quantum well layers, wherein each of the plurality of quantum well layers comprises a material having a tensile strain with respect to the semiconductor substrate.

In some embodiments, the aforementioned integrated structure of the electro-absorption light modulator and the laser diode, wherein each of the plurality of quantum well layers has a tensile strain rate between-0.1% and-2% with respect to the semiconductor substrate.

In some embodiments, in the integrated structure of the electro-absorption light modulator and the laser diode, the quantum well layers have a total stress strain rate less than 0% relative to the semiconductor substrate.

In some embodiments, the integrated structure of the electro-absorption optical modulator and the laser diode further comprises a plurality of tensile strained quantum well layers, wherein the plurality of tensile strained quantum well layers comprise a material having tensile strain relative to the semiconductor substrate, and the plurality of compressive strained quantum well layers comprise a material having compressive strain relative to the semiconductor substrate, wherein the number of tensile strained quantum well layers is greater than the number of compressive strained quantum well layers.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, a total tensile strain rate is a sum of tensile strain rates of the plurality of quantum well layers corresponding to the number of tensile strained quantum well layers relative to the semiconductor substrate, and a total compressive strain rate is a sum of compressive strain rates of the plurality of quantum well layers corresponding to the number of compressive strained quantum well layers relative to the semiconductor substrate, where the total stress strain rate is a sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, a total tensile strain rate is a sum of tensile strain rates of the quantum well layers with respect to the semiconductor substrate, and a total compressive strain rate is a sum of compressive strain rates of the quantum well layers with respect to the semiconductor substrate, wherein the total stress strain rate is a sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate divided by the total number of the quantum well layers is between-0.1% and-2%.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, a number of the quantum well layers of a tensile strained quantum well layer includes a material having a tensile strain with respect to the semiconductor substrate, a number of the quantum well layers of a compressive strained quantum well layer includes a material having a compressive strain with respect to the semiconductor substrate, wherein a total tensile strain rate is a sum of tensile strain rates of the quantum well layers of the tensile strained quantum well layer number with respect to the semiconductor substrate, and a total compressive strain rate is a sum of compressive strain rates of the quantum well layers of the compressive strained quantum well layer with respect to the semiconductor substrate, wherein the total stress strain rate is a sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%.

In some embodiments, the aforementioned integrated structure of the electro-absorption light modulator and the laser diode, wherein the plurality of quantum well layers of each tensile strained quantum well layer has a tensile strain rate between-0.1% and-2% with respect to the semiconductor substrate.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, the plurality of quantum well layers of each compressively strained quantum well layer have a compressive strain greater than or equal to 0.1% and less than or equal to 2% relative to the semiconductor substrate.

In some embodiments, the aforementioned integrated structure of the electro-absorption optical modulator and the laser diode, wherein the total stress-strain rate divided by the total number of quantum well layers is between-0.1% and-2%.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode further comprises a plurality of barrier layers, wherein each of the plurality of barrier layers comprises a material having a compressive strain with respect to the semiconductor substrate.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode further comprises a plurality of barrier layers, wherein each of the plurality of barrier layers has a compressive strain rate greater than or equal to 0.1% and less than or equal to 2% relative to the semiconductor substrate.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode further comprises a plurality of barrier layers, wherein each of the plurality of barrier layers has a thickness greater than or equal to 1nm and less than or equal to 15 nm.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode, wherein each of the plurality of quantum well layers has a thickness greater than or equal to 3nm and less than or equal to 15 nm.

In some embodiments, in the integrated structure of the electro-absorption light modulator and the laser diode, a total number of the quantum well layers is greater than or equal to 3 and less than or equal to 20.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, each of the plurality of quantum well layers has a quantum well layer energy band gap smaller than a barrier layer energy band gap of each of the plurality of barrier layers.

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode, wherein the material forming each of the plurality of quantum well layers comprises one selected from the following group: indium gallium arsenide phosphide (InGaAsP) and indium gallium aluminum arsenide (InGaAlAs).

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode, wherein the material forming each of the plurality of quantum well layers comprises indium gallium arsenide phosphide (InGaAsP), and the material forming each of the plurality of barrier layers comprises indium gallium arsenide phosphide (InGaAsP).

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode, wherein the material forming each of the plurality of quantum well layers comprises indium gallium aluminum arsenide (InGaAlAs), and the material forming each of the plurality of barrier layers comprises indium gallium aluminum arsenide (InGaAlAs).

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode comprises a semiconductor substrate made of indium phosphide (InP).

In some embodiments, the aforementioned integrated structure of the electro-absorption light modulator and the laser diode is selected from one of the following groups: a distributed feedback Laser (DFB Laser) and a distributed bragg reflector Laser (DBR Laser).

In some embodiments, the integrated structure of the electro-absorption light modulator and the laser diode is one in which a wavelength of the transverse magnetic field polarization mode laser is greater than or equal to 1.0 μm and less than or equal to 1.6 μm.

In some embodiments, the total number of the quantum well layers is equal to the total number of the barrier layers of the plurality of barrier layers, and the upper and lower portions of each of the plurality of quantum well layers are respectively adjacent to one of the plurality of barrier layers and the other of the plurality of barrier layers.

In some embodiments, in the integrated structure of the electro-absorption optical modulator and the laser diode, the total number of barrier layers of the plurality of barrier layers is equal to the total number of quantum well layers, and the upper and lower portions of each of the plurality of barrier layers are respectively adjacent to one of the quantum well layers and the other quantum well layer.

In some embodiments, the integrated structure of the electro-absorption optical modulator and the laser diode includes a total number of quantum well layers equal to a total number of barrier layers of the plurality of barrier layers, one of the quantum well layers is adjacent to the lower semiconductor layer, and one of the barrier layers is adjacent to the upper semiconductor layer.

In some embodiments, the integrated structure of the electro-absorption optical modulator and the laser diode includes a total number of quantum well layers equal to a total number of barrier layers of the plurality of barrier layers, one of the plurality of barrier layers is adjacent to the lower semiconductor layer, and one of the plurality of quantum well layers is adjacent to the upper semiconductor layer.

For further understanding of the present invention, the following detailed description of the preferred embodiments will be provided in conjunction with the drawings and figures to illustrate the specific components of the present invention and the functions performed thereby.

Drawings

FIG. 1A is a cross-sectional view of an integrated structure of an electro-absorption light modulator and a laser diode according to an embodiment of the present invention.

FIG. 1B is a schematic cross-sectional view of one embodiment of an electro-absorption light modulator of FIG. 1A.

FIG. 1C is a graph comparing the reverse bias voltage applied to an electro-absorption light modulator and the extinction ratio of two embodiments of an integrated structure of an electro-absorption light modulator and a laser diode according to the present invention.

FIG. 1D is a schematic cross-sectional view of another embodiment of the electro-absorption light modulator of FIG. 1A.

FIG. 1E is a schematic cross-sectional view of yet another embodiment of an electro-absorption light modulator of FIG. 1A.

FIG. 1F is a schematic cross-sectional view of another embodiment of the electro-absorption light modulator of FIG. 1A.

FIG. 2A is a cross-sectional view of an embodiment of an integrated structure of an electro-absorption light modulator and a laser diode according to the prior art.

FIG. 2B is a cross-sectional schematic view of the electro-absorption light modulator of FIG. 2A.

List of reference numerals: 1-integrated structure of electro-absorption light modulator and laser diode; 10-a semiconductor substrate; 11-front end of semiconductor substrate; 12-the back end of the semiconductor substrate; 2-a laser diode; 3-an electro-absorption light modulator; 4-a lower semiconductor layer; 5-an active layer; a 50-quantum well layer; 51-barrier layer; 6-an upper semiconductor layer; 9-integration of the electro-absorption light modulator and the laser diode; 90-an electro-absorption light modulator; 91-a laser diode; 92-a semiconductor substrate; 93-a lower semiconductor layer; 94-active layer; 95-an upper semiconductor layer; 96-front end of semiconductor substrate; 97-back end of semiconductor substrate; 98-quantum well layer; 99-barrier layer.

Detailed Description

Fig. 1A is a schematic cross-sectional view of an integrated structure of an electro-absorption light modulator and a laser diode according to an embodiment of the invention. FIG. 1B is a cross-sectional view of one embodiment of the electro-absorption light modulator of FIG. 1A. The integrated structure 1 of the electro-absorption light modulator and the laser diode of the present invention comprises a semiconductor substrate 10, a laser diode 2 and an electro-absorption light modulator 3. Wherein the laser diode 2 is formed on a back end 12 of the semiconductor substrate 10(ii) a The electro-absorption light modulator 3 is formed on a front end 11 of the semiconductor substrate 10. Wherein the Laser diode 2 is a Distributed Feedback Laser (DFB Laser) or a Distributed Bragg Reflector Laser (DBR Laser), and the Laser diode 2 has a Laser cavity (not shown), and a quantum well layer (not shown) of the Laser cavity includes a material having a Tensile Strain (Tensile Strain) with respect to the semiconductor substrate 10, such that the Laser cavity of the Laser diode 2 forms a Transverse Magnetic Polarization Mode (TM Mode) Laser cavity. And the transverse magnetic field polarization mode laser resonant cavity of the laser diode 2 is used for exciting a transverse magnetic field polarization mode laser. In some embodiments, the transverse magnetic field polarization mode laser has a wavelength greater than or equal to 1.0 μm and less than or equal to 1.6 μm. Wherein the electro-absorption light modulator 3 comprises a lower semiconductor layer 4, an active layer 5 and an upper semiconductor layer 6. The lower semiconductor layer 4 is formed on the front end 11 of the semiconductor substrate 10; the active layer 5 is formed on the lower semiconductor layer 4; the upper semiconductor layer 6 is formed on the active layer 5. The active layer 5 includes a plurality of barrier layers 51 and a plurality of quantum well layers 50, and the total number of barrier layers 51 is one; the total number of quantum well layers 50 is one quantum well layer total number; the total number of the barrier layers is equal to the sum of the total number of the quantum well layers, and the total number of the quantum well layers is greater than or equal to 3 and less than or equal to 20. The active layer 5 is formed by alternately stacking a plurality of barrier layers 51 and a plurality of quantum well layers 50, such that one barrier layer 51 is disposed above and below any one quantum well layer 50, respectively, and the bottommost portion of the active layer 5 is a barrier layer 51, and the topmost portion of the active layer 5 is a barrier layer 51. Wherein the material constituting the semiconductor substrate 10 includes indium phosphide (InP). The material constituting the quantum well layer 50 includes one selected from the following group: indium gallium arsenide phosphide (InGaAsP) and indium gallium aluminum arsenide (InGaAlAs). In some embodiments, the material comprising the quantum well layer 50 comprises indium gallium arsenide phosphide (InGaAsP), and the material comprising the barrier layer 51 comprises indium gallium arsenide phosphide (InGaAsP). In other embodiments, the material comprising the quantum well layer 50 comprises indium gallium aluminum arsenide (InGaAlAs), and is comprisedThe material of the barrier layer 51 includes indium gallium aluminum arsenide (InGaAlAs). Wherein each quantum well layer 50 has an energy band gap smaller than that of each barrier layer 51. Each quantum well layer 50 has a thickness greater than or equal to 3nm and less than or equal to 15 nm. Each barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 15 nm. In a preferred embodiment, at least one of the quantum well layers 50 comprises a material having a tensile strain rate of between-0.1% and-2% relative to the semiconductor substrate 10 (i.e., the material comprising the quantum well layer 50 has a smaller lattice constant than the material comprising the semiconductor substrate 10); and each of the barrier layers 51 includes a material having a compressive strain rate of greater than or equal to 0.1% and less than or equal to 2% with respect to the semiconductor substrate 10 (i.e., the material constituting the barrier layer 51 has a lattice constant greater than that of the material constituting the semiconductor substrate 10); and wherein the sum of the stress-strain rates of all the quantum well layers 50 with respect to the semiconductor substrate 10 is a total stress-strain rate, wherein the total stress-strain rate is a tensile strain rate (i.e., the total stress-strain rate is less than 0%). Since the electro-absorption Light modulator 3 has at least one quantum well layer 50 under tensile strain, the valence band of the tensilely strained quantum well layer 50 (with a tensile strain rate between-0.1% and-2%) is separated into a Heavy Hole sub-band (Light Hole sub-band) and a Light Hole sub-band (Light Hole sub-band), wherein the Light Hole sub-band is located at the top of the valence band and the Heavy Hole sub-band is located at the bottom of the valence band. Thus, the Energy required to transition from the Lowest Energy state Electron sub-band (Lowest Energy Electron sub-band) to the Lowest Energy state Light hole sub-band (Lowest Energy Light hole sub-band) is less than the Energy required to transition from the Lowest Energy state Electron sub-band to the Lowest Energy state Heavy hole sub-band (Lowest Energy Heavy hole sub-band). This facilitates the transition from the lowest energy state electron sub-band to the lowest energy state light hole sub-band (the transition occurs when the energy of the incident laser light is greater than the energy required for the transition from the lowest energy state electron sub-band to the lowest energy state light hole sub-band). Since the laser light excited by the transverse magnetic field polarization mode laser cavity of the laser diode 2 is transverse magnetic field polarization mode (TM mode) laser light,when the transverse magnetic field polarization mode laser passes through the electro-absorption light modulator 3, the absorption coefficient alpha of the electro-absorption light modulator 3_TMThe method comprises the following steps:

α_TM＝α_LH，

wherein alpha is_LHThe absorption coefficient of light holes is shown. Therefore, when the transverse magnetic polarization mode laser passes through the electro-absorption light modulator 3, the quantum well layer 50 (with a tensile strain rate between-0.1% and-2%) formed by the material having tensile strain with respect to the semiconductor substrate 10 in the electro-absorption light modulator 3 mainly generates a transition from the lowest energy state electron sub-band to the lowest energy state light hole sub-band, and has a higher absorption rate for the transverse magnetic polarization mode laser.

Absorption coefficient alpha of prior art electro-absorption light modulator 90_TEThe method comprises the following steps:

wherein alpha is_LHIs the absorption coefficient of light holes, and alpha_HHThe absorption coefficient of heavy holes is shown. The prior art electro-absorption light modulator 90 primarily produces a transition (α) from the lowest energy state electron sub-band to the lowest energy state heavy hole sub-band_HHPredominant). In contrast, the absorption coefficient α of the electro-absorption light modulator 3 of the present invention_TMThe method comprises the following steps:

α_TM＝α_LH，

wherein alpha is_LHThe absorption coefficient of light holes is shown. The electro-absorption light modulator 3 of the present invention mainly generates the transition (alpha) from the lowest energy state electron sub-band to the lowest energy state light hole sub-band_LHPredominant). Thus, the absorption coefficient α of the electro-absorption light modulator 3 of the invention_TMHaving an absorption coefficient alpha which is higher than that of the prior art electro-absorption light modulator 90_TEIs large. Please refer to the following table, which shows the integrated structure 1 of the electro-absorption light modulator and the laser diode of the present invention and the integrated structure of the electro-absorption light modulator and the laser diode of the prior artComparison of 9:

table one:

FIG. 1C is a graph comparing the reverse bias voltage and extinction ratio applied to an electro-absorption light modulator according to one embodiment of the present invention and two embodiments of the present invention. In FIG. 1C, a prior art embodiment is an integrated structure 9 of an electro-absorption light modulator and laser diode of the embodiment of FIGS. 2A and 2B; wherein the material constituting the semiconductor substrate 92 of the related art is indium phosphide (InP); the laser diode 91 in the prior art has a transverse electric field polarization mode laser resonant cavity, and the laser excited by the laser diode is transverse electric field polarization mode laser; the active layer 94 of the prior art electro-absorption light modulator 90 has 15 quantum well layers 98 and 16 barrier layers 99, the active layer 94 is formed by alternately stacking 16 barrier layers 99 and 15 quantum well layers 98, such that one barrier layer 99 is respectively disposed above and below any one quantum well layer 98, the bottommost layer of the active layer 94 is a barrier layer 99, and the topmost layer of the active layer 94 is a barrier layer 99; wherein the material constituting the barrier layer 99 is indium gallium arsenide phosphide (InGaAsP); the material constituting the quantum well layer 98 includes indium gallium arsenide phosphide (InGaAsP); wherein each barrier layer 99 has a compressive strain rate of + 0.45% relative to the semiconductor substrate 92; wherein each quantum well layer 98 has a compressive strain rate of + 0.006% relative to the semiconductor substrate 92. In FIG. 1C, the structure of two embodiments of the present invention is the same as the integrated structure 1 of the electro-absorption light modulator and laser diode of the embodiments of FIGS. 1A and 1B. Wherein the semiconductor substrate 10 constituting the present invention is indium phosphide (InP); the laser diode 2 of the invention is provided with a transverse magnetic field polarization mode laser resonant cavity, and the laser excited by the laser diode is transverse magnetic field polarization mode laser; the active layer 5 of the electro-absorption light modulator 3 of the present invention has 15 quantum well layers 50 and 16 barrier layers 51, the active layer 5 is formed by alternately stacking 16 barrier layers 51 and 15 quantum well layers 50, such that one barrier layer 51 is respectively disposed above and below any one quantum well layer 50, the bottommost layer of the active layer 5 is a barrier layer 51, and the topmost layer of the active layer 5 is a barrier layer 51; wherein the material constituting the barrier layer 51 is indium gallium arsenide phosphide (InGaAsP); wherein each of the barrier layers 51 has a compressive strain rate of + 0.45% with respect to the semiconductor substrate 10; the material constituting the quantum well layer 50 includes indium gallium arsenide phosphide (InGaAsP). In fig. 1C, the two embodiments of the present invention are mainly different in that: in one of two embodiments of the present invention, each quantum well layer 50 has a tensile strain rate of-0.185% relative to the semiconductor substrate 10; and the other of the two embodiments of the present invention has each quantum well layer 50 with a tensile strain rate of-0.259% relative to the semiconductor substrate 10. In fig. 1C, the difference between the integrated structure 9 of the prior art electro-absorption light modulator and the laser diode and the integrated structure of the electro-absorption light modulator and the laser diode according to the two embodiments of the present invention is shown in the following table two:

as is apparent from the comparison of fig. 1C, regardless of the tensile strain rate of-0.185% or-0.259% of the quantum well layer 50 of the active layer 5 of the electro-absorption optical modulator 3 of the two embodiments of the present invention relative to the semiconductor substrate 10, the extinction ratio of the electro-absorption optical modulator 3 of the two embodiments of the present invention to the transverse magnetic field polarization mode (TM mode) laser (wavelength of 1290nm) is greater than that of the prior art electro-absorption optical modulator 90 (the quantum well layer 98 of the active layer 94 thereof is + 0.006% relative to the compressive strain rate of the semiconductor substrate 92) to the transverse electric field polarization mode (TE mode) laser (wavelength of 1290 nm). Especially when the reverse bias applied to the electro-absorption light modulator 3/prior art electro-absorption light modulator 90 of the present invention is larger than 0.7V, the extinction ratio of the electro-absorption light modulator 3 of the two embodiments of the present invention to the transverse magnetic field polarization mode (TM mode) laser (wavelength 1290nm) is much larger than that of the prior art electro-absorption light modulator 90 to the transverse electric field polarization mode (TE mode) laser (wavelength 1290 nm). In contrast, two embodiments of the present invention were compared in which the quantum well layer 50 of the active layer 5 of the electro-absorption light modulator 3 had a larger tensile strain rate (-0.259%) relative to the semiconductor substrate 10 for a transverse magnetic field polarized mode (TM mode) laser (wavelength 1290nm) extinction ratio than the quantum well layer 50 had a smaller tensile strain rate (-0.185%) relative to the semiconductor substrate 10 for a transverse magnetic field polarized mode (TM mode) laser (wavelength 1290 nm). Especially when the reverse bias applied to the electro-absorption light modulator 3 of the present invention is larger than 0.7V, the quantum well layer 50 of the active layer 5 of the electro-absorption light modulator 3 has an extinction ratio of the larger of the tensile strain rate (-0.259%) with respect to the semiconductor substrate 10 to the transverse magnetic field polarization mode (TM mode) laser (wavelength of 1290nm) more significantly larger than the extinction ratio of the quantum well layer 50 having the smaller of the tensile strain rate (-0.185%) with respect to the semiconductor substrate 10 to the transverse electric field polarization mode (TE mode) laser (wavelength of 1290 nm). Therefore, the integrated structure 1 of the electro-absorption light modulator and the laser diode of the present invention can indeed achieve the purpose of increasing the extinction ratio of the laser light (transverse magnetic field polarization mode laser light) excited by the laser diode 2 by the electro-absorption light modulator 3.

FIG. 1D is a cross-sectional view of another embodiment of the electro-absorption light modulator of FIG. 1A. The main structure of the embodiment of fig. 1D is substantially the same as that of the embodiment of fig. 1B, however, the active layer 5 includes a plurality of barrier layers 51 and a plurality of quantum well layers 50, and the total number of barrier layers 51 is one; the total number of quantum well layers 50 is one quantum well layer total number; the total number of the quantum well layers is equal to the sum of the total number of the barrier layers, and is more than or equal to 3 and less than or equal to 20. The active layer 5 is formed by alternately stacking a plurality of barrier layers 51 and a plurality of quantum well layers 50, such that one quantum well layer 50 is disposed above and below any one of the barrier layers 51, the bottom of the active layer 5 is a quantum well layer 50, and the top of the active layer 5 is a quantum well layer 50.

FIG. 1E is a cross-sectional view of another embodiment of the electro-absorption light modulator of FIG. 1A. The main structure of the embodiment of fig. 1E is substantially the same as that of the embodiment of fig. 1B, however, the active layer 5 includes a plurality of barrier layers 51 and a plurality of quantum well layers 50, and the total number of barrier layers 51 is one; the total number of quantum well layers 50 is one quantum well layer total number; the total number of the quantum well layers is equal to that of the barrier layers, and is more than or equal to 3 and less than or equal to 20. The active layer 5 is formed by alternately stacking a plurality of barrier layers 51 and a plurality of quantum well layers 50, wherein the bottom of the active layer 5 is a barrier layer 51, and the top of the active layer 5 is a quantum well layer 50.

FIG. 1F is a cross-sectional view of another embodiment of the electro-absorption light modulator of FIG. 1A. The main structure of the embodiment of fig. 1F is substantially the same as that of the embodiment of fig. 1B, however, the active layer 5 includes a plurality of barrier layers 51 and a plurality of quantum well layers 50, and the total number of barrier layers 51 is one; the total number of quantum well layers 50 is one quantum well layer total number; the total number of the quantum well layers is equal to that of the barrier layers, and is more than or equal to 3 and less than or equal to 20. The active layer 5 is formed by alternately stacking a plurality of barrier layers 51 and a plurality of quantum well layers 50, wherein the bottom of the active layer 5 is a quantum well layer 50, and the top of the active layer 5 is a barrier layer 51.

In some embodiments, at least one quantum well layer 50 comprises a material having a tensile strain relative to the semiconductor substrate 10 at a tensile strain rate between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%.

In some embodiments, the plurality of quantum well layers 50 have a total stress strain rate relative to the semiconductor substrate 10 of less than 0%. In some embodiments, the plurality of quantum well layers 50 have a total stress strain rate relative to the semiconductor substrate 10 divided by the total number of quantum well layers of the quantum well layers 50 of between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%.

In some embodiments, each quantum well layer 50 comprises a material having a tensile strain relative to the semiconductor substrate 10 at a tensile strain rate between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%. In some embodiments, the plurality of quantum well layers 50 have a total stress strain rate relative to the semiconductor substrate 10 of less than 0%. In some embodiments, the plurality of quantum well layers 50 have a total stress strain rate relative to the semiconductor substrate 10 divided by the total number of quantum well layers of the quantum well layers 50 of between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%.

In some embodiments, the quantum well layers 50 of the plurality of quantum well layers 50 including a tensile strained quantum well layer number include materials having tensile strain relative to the semiconductor substrate 10, and the quantum well layers 50 of a compressive strained quantum well layer number include materials having compressive strain relative to the semiconductor substrate 10; the number of tensile strain quantum well layers is larger than that of compressive strain quantum well layers. In some embodiments, the quantum well layers 50 of each tensile strained quantum well layer number have a tensile strain rate relative to the semiconductor substrate 10 of between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%. In some embodiments, the quantum well layers 50 of each compressively strained quantum well layer number have a compressive strain rate relative to the semiconductor substrate 10 of greater than or equal to 0.1% and less than or equal to 2%, greater than or equal to 0.1% and less than or equal to 1.5%, greater than or equal to 0.1% and less than or equal to 1.2%, greater than or equal to 0.1% and less than or equal to 1%, greater than or equal to 0.1% and less than or equal to 0.8%, greater than or equal to 0.1% and less than or equal to 0.6%, or greater than or equal to 0.1% and less than or equal to 0.4%. In some embodiments, the total tensile strain rate is the sum of tensile strain rates of the quantum well layers 50 with respect to the semiconductor substrate 10 for the number of tensile strained quantum well layers, and the total compressive strain rate is the sum of compressive strain rates of the quantum well layers 50 with respect to the semiconductor substrate 10 for the number of compressive strained quantum well layers, wherein the total stress strain rate is the sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%. In some embodiments, the total tensile strain rate is the sum of the tensile strain rates that the quantum well layers 50 of the number of tensile strained quantum well layers have with respect to the semiconductor substrate 10, the total compressive strain rate is the sum of the compressive strain rates of the quantum well layers 50 of the number of compressively strained quantum well layers with respect to the semiconductor substrate 10, wherein the total stress strain rate is the sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate divided by the total number of quantum well layers of the quantum well layer 50 is between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%.

In some embodiments, the quantum well layers 50 of the plurality of quantum well layers 50 including a tensile strained quantum well layer number include materials having tensile strain relative to the semiconductor substrate 10, and the quantum well layers 50 of a compressive strained quantum well layer number include materials having compressive strain relative to the semiconductor substrate 10; wherein the total tensile strain rate is the sum of tensile strain rates of the quantum well layers 50 with the tensile strain quantum well layer number relative to the semiconductor substrate 10, and the total compressive strain rate is the sum of compressive strain rates of the quantum well layers 50 with the compressive strain quantum well layer number relative to the semiconductor substrate 10, wherein the total stress strain rate is the sum of the total tensile strain rate and the total compressive strain rate, and the total stress strain rate is less than 0%. In some embodiments, the quantum well layers 50 of each tensile strained quantum well layer number have a tensile strain rate relative to the semiconductor substrate 10 of between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%. In some embodiments, the quantum well layers 50 of each compressively strained quantum well layer number have a compressive strain rate relative to the semiconductor substrate 10 of greater than or equal to 0.1% and less than or equal to 2%, greater than or equal to 0.1% and less than or equal to 1.5%, greater than or equal to 0.1% and less than or equal to 1.2%, greater than or equal to 0.1% and less than or equal to 1%, greater than or equal to 0.1% and less than or equal to 0.8%, greater than or equal to 0.1% and less than or equal to 0.6%, or greater than or equal to 0.1% and less than or equal to 0.4%. In some embodiments, the total stress strain rate divided by the total number of quantum well layers of the quantum well layer 50 is between-0.1% and-2%, between-0.1% and-1.5%, between-0.1% and-1.2%, between-0.1% and-1%, between-0.1% and-0.8%, between-0.1% and-0.6%, or between-0.1% and-0.4%.

In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 18 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 20 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 23 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 25 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 30 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 13 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 11 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 3nm and less than or equal to 10 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 1nm and less than or equal to 15 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 2nm and less than or equal to 15 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 4nm and less than or equal to 15 nm. In some embodiments, the quantum well layers 50 have a thickness greater than or equal to 5nm and less than or equal to 15 nm.

In some embodiments, the barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 18 nm. In some embodiments, the thickness of the barrier layer 51 is greater than or equal to 1nm and less than or equal to 21 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 24 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 27 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 30 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 1nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 2nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 3nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 4nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 5nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 6nm and less than or equal to 15 nm. In some embodiments, the barrier layer 51 has a thickness greater than or equal to 7nm and less than or equal to 15 nm.

In some embodiments, the total number of quantum well layers is greater than or equal to 5 and less than or equal to 20. In some embodiments, the total number of quantum well layers is greater than or equal to 7 and less than or equal to 20. In some embodiments, the total number of quantum well layers is greater than or equal to 3 and less than or equal to 22. In some embodiments, the total number of quantum well layers is greater than or equal to 3 and less than or equal to 24. In some embodiments, the total number of quantum well layers is greater than or equal to 3 and less than or equal to 27. In some embodiments, the total number of quantum well layers is greater than or equal to 3 and less than or equal to 30.

While the invention has been described in connection with specific embodiments and implementations, many modifications and variations are possible in light of the above teaching or may be acquired from practice of the invention, and it is intended that all such modifications and variations be considered as within the spirit and scope of the invention.

In summary, the present invention provides an integrated structure of an electro-absorption light modulator and a laser diode, which is advantageous for industrial application.