阅读说明：本技术 一种三端式8字环形量子级联激光器 (Three-end 8-shaped annular quantum cascade laser ) 是由 袁国慧 王卓然 林志远 张鹏年 于 2020-02-27 设计创作，主要内容包括：本发明公开了一种三端式8字环形量子级联激光器,该激光器包括由下至上依次设置的衬底、集电极、量子级联结构层、量子能级匹配层、基极、发射极,发射极与基极之间、量子级联结构层与集电极之间均有阶梯状设置；该激光器还包括设置于集电极顶部或衬底下方的集电极电极、设置于基极顶部的基极电极、设置于发射极顶部的发射极电极。激光器上还刻蚀有8字环形波导和与8字环形波导耦合的条形直波导,条形直波导包括输入段和耦合段。该三端式8字环形量子级联激光器设计简单、可调谐特性好、可多波长或宽谱或混沌激光或频率梳输出,且能够有效降低广泛中红外、太赫兹应用中中红外、太赫兹源的应用成本。(The invention discloses a three-terminal 8-shaped annular quantum cascade laser, which comprises a substrate, a collector, a quantum cascade structure layer, a quantum energy level matching layer, a base and an emitter which are sequentially arranged from bottom to top, wherein the emitter and the base are arranged in a step shape, and the quantum level connection structure layer and the collector are arranged in a step shape; the laser also comprises a collector electrode arranged on the top of the collector or below the substrate, a base electrode arranged on the top of the base electrode, and an emitter electrode arranged on the top of the emitter. The laser is also etched with an 8-shaped annular waveguide and a bar-shaped straight waveguide coupled with the 8-shaped annular waveguide, and the bar-shaped straight waveguide comprises an input section and a coupling section. The three-terminal 8-shaped annular quantum cascade laser is simple in design, good in tunable characteristic, capable of outputting multi-wavelength or wide-spectrum or chaotic laser or frequency comb, and capable of effectively reducing application cost of mid-infrared and terahertz sources in wide mid-infrared and terahertz applications.)

1. A three-terminal 8-shaped annular quantum cascade laser is characterized in that: the laser comprises a substrate (7), a collector (8), a quantum level connection structure layer (9), a quantum level matching layer (10), a base (11) and an emitter (12) which are sequentially arranged from bottom to top, wherein the collector (8) and the quantum cascade structure layer (9) and the base (11) and the emitter (12) are arranged in a step shape;

the three-terminal 8-shaped annular quantum cascade laser further comprises a collector electrode (13) arranged at the top of the collector electrode (8) or below the substrate (7), a base electrode (14) arranged at the top of the base electrode (11), and an emitter electrode (15) arranged at the top of the emitter electrode (12);

the laser is further etched with an 8-shaped annular waveguide (19) and a bar-shaped straight waveguide (18) coupled with the 8-shaped annular waveguide (19), the 8-shaped annular waveguide (19) and the bar-shaped straight waveguide (18) are etched to any depth from the top of an emitter to the top of a base electrode (11), the top of a quantum energy level matching layer (10), the top of a quantum cascade structure layer (9) or the top of a collector electrode (8), wherein at least one side of the inside or outside of an annular region of the 8-shaped annular waveguide (19) is etched to any depth from the top of the emitter to the top of the base electrode, and the bar-shaped straight waveguide (18) comprises an input section (17) and a coupling section (16);

the quantum cascade structure layer (9) is formed by serially stacking at least two QC L stack units with the same structure, each QC L stack unit comprises at least two QC L sub-units with the same structure, each QC L sub-unit comprises an active region and an injection region, each injection region comprises a plurality of sections of doping regions, and the doping concentration parameters of at least one section of doping region are different between different QC L sub-units.

2. The triple-ended 8-ring quantum cascade laser as claimed in claim 1, wherein at least one of the QC L subunits comprises two or more doped regions, and at least one of the QC L subunits has a doped region with a doping concentration parameter different from the doping concentration parameters of the other doped regions.

3. The triple-ended 8-shaped ring quantum cascade laser according to claim 1, wherein the quantum cascade structure layer (9) comprises N QC L stack units, namely a first QC L stack unit AB (1), an ith QC L stack unit AB (2), an Nth QC L stack unit AB (3), or a first QC L stack unit ABB (4), an ith QC L stack unit ABB (5), and an Nth QC L stack unit ABB (6), wherein i and N are integers greater than 1, and i is less than or equal to N.

4. The triple-ended 8-ring quantum cascade laser according to claim 1, wherein the QC L subunit adopts a U-L state transition design, and the U state and the L state are any one of a single energy state, a multiple energy state or a continuum state, and the multiple energy state comprises at least two energy states.

5. The three-terminal 8-shaped ring quantum cascade laser according to claim 1, wherein the working or lasing wavelength corresponding to the active region of the QC L subunit is in the mid-infrared or terahertz band.

6. The three-terminal 8-ring quantum cascade laser of claim 1, wherein: the number of collector electrodes (13) in the three-terminal 8-shaped annular quantum cascade laser is at least one, the number of base electrodes (14) is at least one, and the number of emitter electrodes (15) is at least one.

7. The three-terminal 8-ring quantum cascade laser of claim 1, wherein: and a plurality of insulating layers (24) are arranged on the 8-shaped annular waveguide (19) and the base electrode (11) so that the laser forms a multi-section structure and is provided with a plurality of sections of control subunits.

8. The three-terminal 8-ring quantum cascade laser of claim 7, wherein: the control subunit of each section can be controlled by a group of independent section voltages, the group of independent section voltages at least comprises three electrode control voltages of a collector electrode (8), a base electrode (11) and an emitter electrode (12), and the value of each group of independent electrode control voltages is any one of positive voltage, zero voltage or negative voltage.

9. The three-terminal 8-ring quantum cascade laser of claim 7, wherein: in each segment of the control subunit, the base-emitter bias controls the current density of the quantum cascade structure layer (9) injected into the segment, and the base-collector bias controls the device bias of the quantum cascade structure layer (9) in the segment.

10. The triple-ended 8-ring quantum cascade laser according to claim 7, wherein at least two of said QC L stack units are capable of operating or lasing, and at least one of said QC L subunits in each of said operating or lasing QC L stack units is capable of operating or lasing, under a combination of applied base-emitter bias and base-collector bias device bias.

11. The triple-ended 8-ring quantum cascade laser according to claim 7, wherein at least two of said QC L stack units are capable of operating or lasing simultaneously, and at least one of said QC L subunits in each of said operating or lasing QC L stack units is capable of operating or lasing at a particular applied base-emitter bias and base-collector bias device bias combination.

12. The triple-ended 8-ring quantum cascade laser according to claim 7, wherein at least two of said QC L stack units are capable of operating or lasing simultaneously when the applied base-emitter bias and base-collector bias device bias combination is changed, and at least one of said QC L subunits in each of said operating or lasing QC L stack units is capable of operating or lasing.

13. The triple-ended 8-ring quantum cascade laser as claimed in claim 7, wherein at least two of said QC L stack units are capable of operating or lasing simultaneously when the applied base-emitter bias and base-collector bias device bias combinations are changed, at least one of said QC L subunits in each of said operating or lasing QC L stack units is capable of operating or lasing, and the operating or lasing output wavelength is changed by changing the applied base-emitter bias and base-collector bias device bias combinations.

14. The three-terminal 8-ring quantum cascade laser of claim 13, wherein: the working or lasing outputs are superimposed into a multi-wavelength output or a broad spectrum output or a frequency comb output.

15. The three-terminal 8-ring quantum cascade laser of claim 13, wherein: the working or lasing outputs are superimposed into a multi-wavelength output or a wide-spectrum output or a frequency comb output that changes as the base-emitter bias and the base-collector bias device bias voltage combination applied changes.

16. Use of a ring quantum cascade laser according to claim 15, characterized in that: under specific external light injection, chaotic laser can be formed in the wavelength range of the tunable multi-wavelength output or wide-spectrum output, and the chaotic laser output changes along with the change of an injected external signal or along with the change of the applied base-emitter bias voltage and the bias voltage combination of the base-collector bias device.

Technical Field

The invention belongs to the technical field of semiconductor lasers, and particularly relates to a three-terminal 8-shaped annular quantum cascade laser.

Background

Compared with the traditional carrier conduction band-valence band excited radiation transfer mechanism of a Quantum well laser, the Quantum Cascade laser (Quantum Cascade L ases, QC L s) can directly generate intermediate infrared and terahertz band outputs due to the unique carrier conduction band inner sub-band transfer Cascade mechanism, compared with the existing intermediate infrared and terahertz output generation methods, such as a photoconductive mixing method, a semiconductor built-in electric field method, an optical rectification method, an electro-optical sampling method and the like, the intermediate infrared and terahertz output structure based on QC L s has the advantages of high conversion efficiency, simple cavity structure, good on-chip integration and the like, is widely applied to various civil and military applications including DNA detection, biological tissue imaging, non-contact testing, public safety monitoring, gas component detection, THz wireless communication and the like, and in order to improve the universality of QC L s in different applications and reduce the application cost, the intermediate infrared or terahertz output of the QC L s is required to have better tunable characteristics or have multi-wavelength or wide-spectrum output characteristics.

In order to improve the tunable characteristic of QC L s, methods adopted by the mainstream at present include an external cavity grating tuning method, a strong magnetic field method, a distributed feedback structure method, a Sampling Grating Reflector (SGR) method and the like.

In order to obtain multi-wavelength or wide-spectrum QC L s mid-infrared or terahertz output, the main method at present is to design an active region of a quantum cascade structure of QC L s, so that the energy states of an upper sub-band and a lower sub-band of the active region are transferred to a single energy state, a double energy state, a single energy state, a continuous state, a QC L multi-core multi-stack structure and the like.

Under the condition of a certain external light injection signal, the laser can generate noise-like wide-spectrum random output with the intensity, frequency and phase changing rapidly in a limited interval, namely chaotic laser. In recent years, chaotic laser has been widely researched and applied in the fields of secure optical communication, laser ranging, optical fiber breakpoint detection and the like.

The frequency comb is coherent radiation generated by a laser light source, the spectrum of the frequency comb is composed of a plurality of completely equidistant modes with definite phase relation, and the frequency comb is widely applied to a plurality of fields such as nano-scale distance measurement, femtosecond time-frequency transfer, accurate measurement of physical quantity and the like. At present, the application of the frequency comb gradually extends from a far ultraviolet band to a middle infrared band and a terahertz band. In the middle infrared band, the frequency comb can be widely applied to the fields of environment perception, gas component detection and the like; in the terahertz waveband, the frequency comb can also be used for the aspects of noninvasive imaging, wireless communication, public safety monitoring and the like. The frequency comb has great application value in a plurality of military and civil applications.

At present, aiming at the application in the fields of wide mid-infrared and terahertz, a quantum cascade structure which is simple in design, good in tunable characteristic and capable of outputting multi-wavelength or wide-spectrum or frequency comb or chaotic laser and a device applied by the quantum cascade structure are lacked.

Disclosure of Invention

The invention aims to solve the problems and provides a three-terminal 8-shaped ring quantum cascade laser, which has the advantages of simple design, good tunable characteristic, capability of outputting multi-wavelength or wide-spectrum or chaotic laser or frequency comb, and capability of effectively reducing the application cost of mid-infrared and terahertz sources in wide mid-infrared and terahertz applications.

In order to solve the technical problems, the technical scheme of the invention is as follows: a three-terminal 8-shaped annular quantum cascade laser comprises a substrate, a collector, a quantum cascade structure layer, a quantum energy level matching layer, a base electrode and an emitter which are sequentially arranged from bottom to top, wherein the collector and the quantum cascade structure layer as well as the base electrode and the emitter are arranged in a step shape;

the three-terminal 8-shaped annular quantum cascade laser also comprises a collector electrode arranged at the top of the collector or below the substrate, a base electrode arranged at the top of the base electrode and an emitter electrode arranged at the top of the emitter;

the laser is further etched with an 8-shaped annular waveguide and a bar-shaped straight waveguide coupled with the 8-shaped annular waveguide, the etching depth of the 8-shaped annular waveguide and the bar-shaped straight waveguide is any depth from the top of an emitter to the top of a base, the top of a quantum energy level matching layer, the top of a quantum cascade structure layer or the top of a collector, wherein at least one side of the etching depth in an annular region or outside the annular region of the 8-shaped annular waveguide is only from the top of the emitter to the top of the base, and the bar-shaped straight waveguide comprises an input section and a coupling section;

the quantum cascade structure layer is formed by stacking at least two QC L stack units with the same structure in series, each QC L stack unit comprises at least two QC L subunits with the same structure, each QC L subunit consists of an active region and an injection region, each injection region comprises a plurality of sections of doping regions, and at least one section of doping region among different QC L subunits has different doping concentration parameters.

The quantum level connection structure layer comprises N QC L stack units, namely a first QC L stack unit AB, an ith QC L stack unit AB and an Nth QC L stack unit AB, or a first QC L stack unit ABB, an ith QC L stack unit ABB and an Nth QC L stack unit ABB, wherein i and N are integers larger than 1, and i is not more than N.

It should be noted that the structural composition of the 8-shaped annular waveguide and the bar-shaped straight waveguide can be controlled by controlling the corresponding etching depth, the 8-shaped annular waveguide and the bar-shaped straight waveguide can be etched only from the top of the emitter to the top of the base, that is, the 8-shaped annular waveguide and the bar-shaped straight waveguide structure only contain the emitter, or the 8-shaped annular waveguide and the bar-shaped straight waveguide can be etched from the top of the emitter to the top of the base, the top of the quantum level matching layer, the top of the quantum level connection structure layer or the top of the collector, and if the 8-shaped annular waveguide and the bar-shaped straight waveguide are etched from the top of the emitter to the top of the collector, the 8-shaped annular waveguide and the bar-shaped straight waveguide structure contain the emitter, the base, the quantum level matching layer, and the. In particular, in order to maintain the characteristics of the three-terminal transistor, it is necessary to etch at least one side region of the two regions inside the circular region or outside the circular region of the 8-shaped annular waveguide only to the top of the base region.

Furthermore, the waveguide structure only comprises an emitter type, the cavity structure of the quantum cascade structure layer of the device is mainly an F-P type, and the 8-shaped annular waveguide structure can finely adjust the mode distribution and the traveling wave mode in the F-P cavity of the device. When the 8-shaped annular waveguide structure comprises an emitter, a base, a quantum energy level matching layer and a quantum level connection structural layer, the resonant cavity structure of the quantum cascade structural layer of the whole device is completely changed into an annular resonant cavity, and the mode distribution and the traveling wave mode are completely distributed according to the device characteristics of the annular resonant cavity. That is to say, the etching depth determines the cavity resonance characteristic of the device, and as the etching depth increases, the cavity resonance gradually changes from the F-P type resonance conversion characteristic to the ring resonant cavity resonance characteristic.

The three-terminal 8-shaped annular quantum cascade laser adopting the 8-shaped annular waveguide structure can obtain a cascade enhanced four-wave mixing effect by utilizing strong third-order nonlinearity of the annular structure, and is very favorable for locking the uniformity and the relative phase of different tooth comb mode intervals of an output frequency comb, so that the frequency comb with excellent performance can be generated. In addition, the traveling wave mode of the 8-shaped ring waveguide structure laser and the asymmetric ring waveguide structure of the 8-shaped ring waveguide structure can avoid the spatial hole burning effect caused by the standing wave mode of the laser with a common Fabry-Perot (F-P) structure, and the characteristics of the obtained high-performance frequency comb can be further stabilized and improved.

Further, considering the large-sized 8-shaped ring waveguide structure as a combination of two small-sized ring waveguides that are contacted together, the structures of two sub-ring waveguides in the 8-shaped ring waveguide structure, such as the radius-to-radius ratio of the two ring waveguides and the waveguide shape at the intersection contact of the two small-sized ring waveguides, can be further controlled to further explore the corresponding device applications.

In the above technical solution, preferably, each QC L subunit has only one doped region, and the doping concentration parameters of the doped regions between different QC L subunits are different from each other, and preferably, at least one QC L subunit includes two or more doped regions, and the QC L subunit has at least one doped region, and the doping concentration parameters of the doped regions are different from those of the doped regions of other sections.

In addition, different QC L subunits only have different doping concentration parameters, and other parameters including the layer thickness sequence, the layer material composition sequence and the layer doping position of the subunit structure are all the same.

In the above technical solution, the active region of the QC L subunit is designed by U-L state transition, the U state and the L state are any one of a single energy state, a multiple energy state, or a continuous state, and the multiple energy state includes at least two energy states, and the working or lasing wavelength corresponding to the active region of the QC L subunit is in the mid-infrared or terahertz band.

It should be noted that the quantum cascade structure layer in the present invention can also be applied to the existing periodic sub-unit structure with the active region for outputting mid-infrared and terahertz, that is, the QC L sub-unit structure is not limited to the structure provided by the present invention, and the existing periodic sub-structure units that are designed and can work can be used as the middle "QC L sub-unit" of the quantum cascade structure layer in the present invention to construct the corresponding quantum cascade structure layer.

In the above technical solution, the three-terminal 8-shaped ring quantum cascade laser is a multi-pole device with a QC L stack unit as an active region, and the "multi-pole" refers to a plurality of end-face electrodes perpendicular to the growth direction of a quantum-level junction structure layer, and the multi-pole structure at least includes three electrode structures of an emitter, a base, and a collector.

In the above technical solution, for the three-terminal 8-shaped ring quantum cascade laser structure with a common collector, it is preferable that a plurality of insulating layers are disposed on the 8-shaped ring waveguide and the base to make the laser form a multi-segment structure and have a plurality of segments of control subunits. It should be noted that the three-terminal 8-shaped ring quantum cascade laser may also be used as a subunit, and the foregoing device (as shown in fig. 5 and 6 or fig. 8 and 9) is etched on the same device as an array structure of the subunit, where the array structure may be a chain type or a square array type, different independent electrodes of different array units are insulated from each other, and different array units are coupled by a waveguide, and may be used for exploring further applications.

Furthermore, at least one collector electrode, at least one base electrode and at least one emitter electrode are arranged in the three-terminal 8-shaped annular quantum cascade laser. On the same segment of control subunit, there may be a plurality of electrodes of the same kind, and a collector electrode may be grown on the top of the collector layer on each of the left and right sides of the quantum level junction structure layer, although the spatial positions of the two collector electrodes are different, the roles in the device are the same, and both may belong to the class of "collector electrodes". Likewise, if the spatial position allows, a base electrode may also be grown on top of the base layer on each of the left and right sides of the emitter layer, both base electrodes being classified as "base electrodes".

In the three-terminal 8-shaped annular quantum cascade laser with the multi-section control subunits, each section of control subunit at least comprises three electrode structures of an emitter, a base and a collector. In particular, base-emitter bias (V)_be) Controlling the current density of the quantum cascade structure layer injected into the control subunitPole-collector bias voltage (V)_bc) And controlling the device bias voltage of the quantum cascade structure layer in the control subunit. Each electrode in each type of electrode structure can be controlled by an independent section voltage, the value of the independent section voltage can be any one of positive voltage, zero voltage and negative voltage, all the independent section voltages can be combined differently according to different values, and the output characteristics of the output of the multi-section quantum cascade structure layer in a time domain or a wavelength domain are controlled according to different independent section voltage combinations. The multi-stage control structure is mainly used for respectively controlling the working output of each sub-unit, and further combines the characteristics of the laser to develop corresponding applications, such as frequency comb, ultrafast mode locking, optical switch characteristics and the like.

In the above solution, the applied V_beAnd said V_bcAt least one of said QC L subunits of each of said QC L stack units is capable of operating or lasing under a combination of device bias voltages_beAnd said V_bcUnder the bias combination of devices, at least two QC L stack units can work or radiate, and at least one QC L subunit in each working or radiating QC L stack unit can work or radiate.

In the above solution, the applied V is specified_beAnd said V_bcAt least one of said QC L subunits of each of said QC L stack units is capable of operating or lasing under a combination of device bias voltages_beAnd said V_bcUnder the bias combination of devices, at least two QC L stack units can work or lase simultaneously, and at least one QC L subunit in each working or lasering QC L stack unit can work or lase.

In the above technical solution, the applied V_beAnd said V_bcAt least one of said QC L subunits of each of said QC L stack units is capable of operating or lasing when device bias combinations are changed_beAnd said V_bcAt least two of the QC L stack units can be identical when the device bias combination is changedWhen the working or lasing QC L stack unit works or lases, at least one QC L subunit in each working or lasing QC L stack unit can work or lase.

In the above technical solution, the applied V_beAnd said V_bcAt least one of said QC L sub-units of each of said QC L stack units is capable of operating or lasing with a change in device bias voltage combination, with the operating or lasing output wavelength changing with a change in said applied device bias voltage_beAnd said V_bcWhen the bias combination of the device is changed, at least two QC L stack units can work or lase simultaneously, at least one QC L subunit in each working or lasing QC L stack unit can work or lase, and the working or lasing output wavelength is along with the applied V_beAnd said V_bcThe change in the combination of device biases changes. Further preferably, the V applied_beAnd said V_bcWhen the bias combination of the devices is changed, at least two QC L subunits in each QC L stack unit can work or radiate simultaneously, and the output wavelength of the work or the radiation is along with the applied V_beAnd said V_bcThe change in the combination of device biases changes. More preferably, the V is applied_beAnd said V_bcWhen the bias combination of the device is changed, at least two QC L stack units can work or lase at the same time, at least two QC L subunits in each working or lasing QC L stack unit can work or lase at the same time, and the working or lasing output wavelength is along with the applied V_beAnd said V_bcChanges in the combination of device biases.

The working or lasing outputs are superimposed into a multi-wavelength output or a broad spectrum output or a frequency comb output. Further, the working or lasing outputs are superimposed into a multi-wavelength output or a wide-spectrum output or a frequency comb output, which is dependent on the applied V_beAnd said V_bcThe device bias combination changes.

In the above technical solution, when external light is injected into the input section of the straight waveguide stripDuring signal, an external injection signal can interact with a signal in the 8-shaped annular waveguide structure through the coupling section of the strip-shaped straight waveguide, so that the phase or mode locking of the signal in the 8-shaped annular waveguide structure is influenced, and the output characteristic of the three-terminal 8-shaped annular quantum cascade laser is changed. In particular, the injected external optical signal can enable the three-terminal 8-shaped ring quantum cascade laser to form chaotic laser capable of generating noise-like wide-spectrum random output with rapidly changing intensity, frequency and phase in a limited interval in the wavelength range of the tunable multi-wavelength output or wide-spectrum output, and the chaotic laser output is changed along with the injected external optical signal or along with the applied V_beAnd said V_bcThe change in the combination of device biases changes.

The three-terminal 8-shaped annular quantum cascade laser provided by the invention has the following beneficial effects:

1. according to the quantum cascade structure in the three-terminal 8-shaped annular quantum cascade laser, at least two QC L stack units are stacked in series, and working or lasing is carried out on at least two QC L subunits with different doping concentration parameters contained in each QC L stack unit or at least one QC L subunit contained in each QC L stack unit at different wavelengths, so that the output spectrum window of an applied device is enlarged;

2. the quantum level connection structure layer in the three-terminal 8-shaped annular quantum cascade laser can also be applied to the existing periodic subunit structure with an active region for middle infrared and terahertz output, the structural design of a device can be effectively simplified, and the scheme universality is high;

3. when the V is applied to the three-terminal type 8-shaped annular quantum cascade laser_beAnd said V_bcThe spectral output obtained may be dependent on the applied said V when the combination of device bias voltages is varied_beAnd said V_bcThe device bias combination changes, or when the device is at said applied V_beAnd said V_bcWhen the device is biased under the bias combination, the frequency spectrum output is stable;

4. the three-end type 8-shaped annular quantum cascade laser can be further applied to the application of time domain or frequency domain spectral characteristics of QC L s, such as the application fields of optical frequency comb output, mid-infrared chaotic laser output, mode-locked mid-infrared and terahertz output, multi-wavelength multiplexing mid-infrared and terahertz sources and the like.

Drawings

FIG. 1 is a schematic diagram showing two arrangement structures of a quantum cascade structure layer in the invention, wherein in FIG. 1(a), QC L stack units are AB stacks, and in FIG. 1(b), QC L stack units are ABB stacks.

FIG. 2 is a parameter diagram of A, B two QC L subunits of the quantum cascade structure layer of the present invention.

FIG. 3 is a diagram of QC L subunit with at least one doping concentration parameter in the quantum cascade structure layer of the present invention, and FIG. 3(a) is a diagram of A QC L subunit with N doping concentration parameter_d,1＝N₁，N_d,2＝N₁And the doping concentration parameter of the B QC L subunits is N_d,1＝N₁，N_d,2＝N₂(N₁≠N₂) FIG. 3(b) shows that the doping concentration parameter of the A QC L subcells is N_d,1＝N₁，N_d,2＝N₂(N₁≠N₂) And the doping concentration parameter of the B QC L subunits is N_d,1＝N₁，N_d,2＝N₃(N₃≠N₂)。

Fig. 4 is a schematic diagram of the electric field in one QC L stack unit in the quantum cascade structure layer of the present invention.

Fig. 5 is a schematic structural diagram of a three-terminal 8-shaped ring quantum cascade laser in embodiment 3.

Fig. 6 is a top view of the structure of a three-terminal 8-shaped ring quantum cascade laser in embodiment 3.

Fig. 7 is a schematic energy band diagram of a three-terminal 8-shaped ring quantum cascade laser.

Fig. 8 is a schematic structural view of a three-terminal 8-ring quantum cascade laser according to another embodiment 3.

Fig. 9 is a top view of a three-terminal 8-ring quantum cascade laser according to another embodiment 3.

Fig. 10 is a schematic diagram of a corresponding wide gain spectrum of the three-terminal 8-shaped ring quantum cascade laser in embodiment 3.

Fig. 11 is schematic diagrams of two tunable bandwidth gain spectrums corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 3; fig. 11 (a): base-emitter voltage V_be＝V₁Constant, collector-base voltage from V₂Change to V_2'(ii) a Fig. 11 (b): base-emitter voltage V₁From changing into V_1'Collector-base voltage V_cb＝V₂And is not changed.

Fig. 12 is a schematic diagram of two tunable gain spectrums corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 3; fig. 12 (a): v_be＝V₁Constant, collector-base voltage V_cbAre each V₂”、V_2'And V₂A time device gain spectrum; fig. 12 (b): v_cb＝V₂Constant, base-emitter voltage V_beAre each V₁”、V_1'And V₁The gain spectrum of the device.

Fig. 13 is a schematic structural diagram of a three-terminal 8-shaped ring quantum cascade laser in embodiment 4.

Fig. 14 is a top view of a three-terminal 8-ring quantum cascade laser in embodiment 4.

Fig. 15 is a schematic structural view of a three-terminal 8-ring quantum cascade laser according to another mode of embodiment 4;

fig. 16 is a top view of a three-terminal 8-ring quantum cascade laser according to another embodiment 4.

Fig. 17 is a schematic diagram of two kinds of wide gain spectra corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 4; fig. 17 (a): v_be1＝V₁，V_be2＝V₁，V_be3＝V₁，V_cb1＝V₂，V_cb2＝V_2'，V_cb3＝V₂"gain spectrum in case; fig. 17 (b): v_cb1＝V₂，V_cb2＝V₂，V_cb3＝V₂，V_be1＝V₁，V_be2＝V_1'，V_be3＝V₁"gain spectrum in case.

Fig. 18 is schematic diagrams of two tunable bandwidth gain spectrums corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 4; FIG. 18(a) V_be1＝V₁，V_be2＝V₁，V_be3＝V₁The collector-base bias voltages of the first segment, the second segment and the third segment control segment are respectively set from V₂Becomes V₃、V_2'Becomes V_3'、V₂"becomes V₃", i.e. V_cb1＝V₃，V_cb2＝V_3'，V_cb3＝V₃"time gain spectrum variation diagram; FIG. 18(b) V_cb1＝V₂，V_cb2＝V₂，V_cb3＝V₂The base-emitter bias voltage of the first segment, the second segment and the third segment control segment is respectively changed from V₁Becomes V₃、V_1'Becomes V_3'、V₁"becomes V₃", i.e. V_be1＝V₃，V_be2＝V_3'，V_be3＝V₃"time-spectrum variation of gain.

Fig. 19 is a schematic diagram of two types of super-wide gain spectra corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 4; fig. 19 (a): v_be1＝V₁，V_be2＝V₁，V_be3＝V₁，V_cb1＝V₂，V_cb2＝V_2'，V_cb3＝V₂"super-wide spectrum overlay schematic in case; FIG. 19(b) V_cb1＝V₂，V_cb2＝V₂，V_cb3＝V₂，V_be1＝V₁，V_be2＝V_1'，V_be3＝V₁"super-broad spectrum in case superimposed schematic.

Fig. 20 is a frequency domain output power distribution diagram of the frequency comb output corresponding to the three-terminal 8-shaped ring quantum cascade laser in embodiment 4.

The reference numbers indicate that 1, a first QC L stack unit AB, 2, an ith QC L stack unit AB, 3, an Nth QC L stack unit AB, 4, a first QC L stack unit ABB, 5, an ith QC L stack unit ABB, 6, an Nth QC L stack unit ABB, 7, a substrate, 8, a collector, 9, a quantum level junction structure layer, 10, a quantum level matching layer, 11, a base, 12, an emitter, 13, a collector, 14, a base electrode, 15, an emitter electrode, 16, a coupling segment, 17, an input segment, 18, a straight strip waveguide, 19, 8-shaped annular waveguide, 20, a first segment coupling segment, 21, a second segment coupling segment, 22, a first sub-annular waveguide, 23, a second sub-annular waveguide, 24, an insulating layer, 25, a first sub-straight strip waveguide, 26, and a second sub-straight strip waveguide.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be noted that directional terms and sequential terms such as "upper", "lower", "front", "rear", "left", "right", and the like, which are used in the following embodiments, are only directions with reference to the drawings, and thus, the directional terms are used for illustration and are not intended to limit the present invention.

The invention relates to a three-terminal 8-shaped annular quantum cascade laser, which comprises a substrate 7, a collector 8, a quantum level connection structure layer 9, a quantum level matching layer 10, a base 11 and an emitter 12 which are sequentially arranged from bottom to top, wherein the collector 8 and the quantum level connection structure layer 9 and the base 11 and the emitter 12 are arranged in a step shape. The step-like arrangement is provided for laying the collector electrode 13, the base electrode 14, and the emitter electrode 15.

The three-terminal 8-shaped annular quantum cascade laser further comprises a collector electrode 13 arranged on the collector 8 or below the substrate 7, a base electrode 14 arranged on the base electrode 11, and an emitter electrode 15 arranged on the emitter 12.

An 8-shaped annular waveguide 19 and a strip-shaped straight waveguide 18 coupled with the 8-shaped annular waveguide 19 are further etched on the laser, the etching depths of the 8-shaped annular waveguide 19 and the strip-shaped straight waveguide 18 are any depths from the top of an emitter to the top of a base 11, the top of a quantum energy level matching layer 10, the top of a quantum level connection structure layer 9 or the top of a collector 8, wherein the etching depth of at least one side in an annular region or outside the annular region of the 8-shaped annular waveguide 19 is only from the top of the emitter to the top of the base, and the strip-shaped straight waveguide 18 comprises an input section 17 and a coupling section 16;

as shown in fig. 1, the quantum cascade structure layer 9 in the three-terminal 8-shaped ring quantum cascade laser of the present invention is formed by stacking at least two QC L stack units having the same structure in series, wherein the QC L stack unit includes at least two QC L sub-units having the same structure, each QC L sub-unit is composed of an active region and an injection region, the injection region includes a plurality of doped regions, and at least one doped region has different doping concentration parameters between different QC L sub-units.

In order to facilitate the understanding of the quantum cascade connection structure layer 9 in the three-terminal 8-ring QC laser of the present invention, the following detailed description is given by way of example 1 and example 2, taking the example that each QC L stack unit includes two QC L subunits: