阅读说明：本技术 波长可变激光装置以及波长可变激光装置的制造方法 (Wavelength-variable laser device and method for manufacturing wavelength-variable laser device ) 是由 后藤田光伸 于 2017-12-28 设计创作，主要内容包括：波长可变激光装置具备：第1半导体芯片,具有并联地配置的第1、第2波导；以及第2半导体芯片,与第1、第2波导光学地连接,具有与第1、第2波导协作而构成谐振器的光回路。第1、第2波导分别具有2个以上的表面电极。第2半导体芯片具有与第1、第2波导的表面电极接合的多个电极。(A variable wavelength laser device is provided with: a 1 st semiconductor chip having 1 st and 2 nd waveguides arranged in parallel; and a 2 nd semiconductor chip optically connected to the 1 st and 2 nd waveguides and having an optical circuit which constitutes a resonator in cooperation with the 1 st and 2 nd waveguides. The 1 st and 2 nd waveguides have 2 or more surface electrodes, respectively. The 2 nd semiconductor chip has a plurality of electrodes bonded to the surface electrodes of the 1 st and 2 nd waveguides.)

1, kinds of wavelength-variable laser devices, comprising:

a 1 st semiconductor chip having 1 st and 2 nd waveguides arranged in parallel; and

a 2 nd semiconductor chip optically connected to the 1 st and 2 nd waveguides and having an optical circuit which constitutes a resonator in cooperation with the 1 st and 2 nd waveguides,

the 1 st and 2 nd waveguides are respectively provided with more than 2 surface electrodes,

the 2 nd semiconductor chip has a plurality of electrodes bonded to the surface electrodes of the 1 st and 2 nd waveguides.

2. The wavelength variable laser device according to claim 1,

in the 1 st semiconductor chip, a mirror for reflecting light advancing in the 1 st and 2 nd waveguides to be coupled to the optical circuit of the 2 nd semiconductor chip is provided.

3. The wavelength variable laser device according to claim 1 or 2,

the 1 st and 2 nd waveguides respectively comprise at least 2 of an optical gain region, a reflection grating region and a phase region.

4. The wavelength variable laser device according to any of claims 1 to 3,

the optical circuit has 1 st and 2 nd grating couplers optically connected to the 1 st and 2 nd waveguides.

5. The wavelength variable laser device according to any of claims 1 to 4,

the 1 st and 2 nd grating couplers spatially modulate the grating period or coupling coefficient.

6. The wavelength variable laser device according to claim 4 or 5,

the optical circuit has:

a multi-mode interference coupler having an optical input/output port connected to the 1 st and 2 nd grating couplers via a single-mode waveguide;

a 3 rd grating coupler for extracting light output, optically connected to the multimode interference coupler; and

and the annular mirror is arranged between the output port of the multi-mode interference coupler and the 3 rd grating coupler.

7. The wavelength variable laser device according to any of claims 1 to 6,

the 1 st semiconductor chip is formed of a compound semiconductor,

the 2 nd semiconductor chip is formed of a silicon-based semiconductor.

8, A method for manufacturing a wavelength variable laser device, comprising:

preparing a 1 st semiconductor chip having 1 st and 2 nd waveguides arranged in parallel; and

a step of preparing a 2 nd semiconductor chip having an optical circuit,

the 1 st and 2 nd waveguides are respectively provided with more than 2 surface electrodes,

the 2 nd semiconductor chip has a plurality of electrodes,

the manufacturing method further includes a step of optically connecting the 1 st and 2 nd waveguides and the optical circuit to constitute a resonator by bonding the surface electrodes of the 1 st and 2 nd waveguides and the plurality of electrodes of the 2 nd semiconductor chip by flip chip bonding.

Technical Field

The present invention relates to a wavelength variable laser device that can be used in an optical communication system.

Background

In recent years, in the background of an increase in communication capacity, an intensity modulation method that has been conventionally used in optical fiber communication has shifted to a phase modulation method. Among the Phase Modulation systems, the application of multilevel Phase Modulation such as Phase Shift Keying (PSK) system and Quadrature Amplitude Modulation (QAM) system has been developed.

In addition, as the semiconductor Laser (LD), not only a conventional Distributed Feedback LD (DFB-LD) and a Distributed bragg reflector LD (DBR-LD), but also a wavelength variable laser device covering a c (relative) band and an l (long) band of optical communication is required.

Here, in the multilevel phase modulation system, a narrow line width light source of the order of 10 to 100kHz is required, but the value of the oscillation spectrum line width (hereinafter, line width) of the DFB-LD and the DBR-LD is approximately several MHz or less, and therefore, it is necessary to narrow the line width of the DFB-LD and the DBR-LD, and it is theoretically effective to increase the resonator length (chip size in ) to 1500 to 2000 μm or more, for example.

However, simply increasing the resonator length results in sacrificing the optical output and the Side Mode Suppression Ratio (SMSR: Side Mode Suppression Ratio) of at least 30-40 dB, and thus loss of Mode stability.

On the other hand, , in an external resonator type Semiconductor laser having a structure in which a Semiconductor Optical Amplifier (SOA) which is a III-V group compound Semiconductor chip is added to a resonator formed of an optical component such as a mirror or an etalon (etalon), although the line width can be relatively easily narrowed, the module size is increased and reliability including shock resistance needs to be improved.

Patent document 1 discloses an optical semiconductor device in which a semiconductor optical amplifier and an optical wavelength selection element including a ring resonator based on a silicon waveguide, a diffraction grating, and the like are combined in order to suppress variation in output light without depending on temperature change.

Patent document 2 discloses an optical semiconductor device in which a resonator is formed by a semiconductor optical amplifier chip having a highly reflective coating applied to an end face on the side and a ring mirror of a silicon waveguide, and further an optical modulator formed by a plurality of ring resonators is integrated.

Patent document 3 discloses a wavelength variable laser device in which semiconductor optical amplifiers having different gain spectra and having a high reflection film coated on one end face are arranged on 2 input ports of a wavelength variable ring resonator having an output side coated with a dielectric multilayer film.

Disclosure of Invention

In patent documents 1 to 3, the semiconductor optical amplifier and the external optical circuit are optically connected by butt-joint (butt-jointjunction), and in this structure, high-precision, specifically submicron-precision alignment is required as in in order to suppress the coupling loss to 1dB or less, but for example, long time is required to perform submicron-precision alignment, and the manufacturing cost increases, and particularly, when joining is required at 2 or more sites as in patent document 3, the time required for alignment increases by steps, and thus mass production of the laser device is hindered.

The present invention has been made to solve the above-described problems, and an object thereof is to provide kinds of small-sized wavelength variable laser devices having a narrow line width, which can reduce the requirement for alignment accuracy.

The wavelength variable laser device according to the present invention includes:

a 1 st semiconductor chip having 1 st and 2 nd waveguides arranged in parallel; and

a 2 nd semiconductor chip optically connected to the 1 st and 2 nd waveguides and having an optical circuit which constitutes a resonator in cooperation with the 1 st and 2 nd waveguides,

the 1 st and 2 nd waveguides are respectively provided with more than 2 surface electrodes,

the 2 nd semiconductor chip has a plurality of electrodes bonded to the surface electrodes of the 1 st and 2 nd waveguides.

According to the present invention, the resonator has the 1 st and 2 nd waveguides arranged in parallel with the 1 st semiconductor chip and the optical circuit provided in the 2 nd semiconductor chip as the constituent elements, and thus the resonator length can be increased to obtain a wavelength variable laser device having a narrow line width. In addition, by bonding the surface electrode of the waveguide provided in the 1 st semiconductor chip and the electrode of the 2 nd semiconductor chip, the wavelength variable laser device can be made narrower in line width and smaller in size at the same time. Further, flip chip bonding can be used for bonding the 1 st semiconductor chip and the 2 nd semiconductor chip, and the alignment accuracy at the time of bonding can be reduced to, for example, the order of micrometers.

Drawings

Fig. 1A is a plan view showing a variable wavelength laser device according to embodiment 1 of the present invention.

Fig. 1B is a cross-sectional view of fig. 1A taken along the line a-a and viewed in the direction of the arrows.

Fig. 2 is a cross-sectional view showing the 1 st semiconductor chip.

Fig. 3A is a plan view showing the 1 st semiconductor chip.

Fig. 3B is a perspective view of the waveguide of the 1 st semiconductor chip shown in fig. 3A as viewed from the bottom surface side.

Fig. 4 is a cross-sectional view of fig. 3A taken along the line C-C and viewed in the direction of the arrows.

Fig. 5A is a plan view showing the 2 nd semiconductor chip.

Fig. 5B is a cross-sectional view of fig. 5A taken along the line D-D and viewed in the direction of the arrow.

Fig. 6A is a plan view showing behavior of light when the wavelength variable laser device according to embodiment 1 of the present invention is operated.

Fig. 6B is a cross-sectional view of fig. 6A taken along the line E-E and viewed in the direction of the arrow.

Fig. 7 is a diagram illustrating the oscillation wavelength of the wavelength variable laser device in the initial state.

Fig. 8 is a diagram for explaining a method of adjusting the oscillation wavelength of the wavelength variable laser device.

Fig. 9 is a diagram for explaining a method of adjusting the oscillation wavelength of the wavelength variable laser device.

Fig. 10 is a diagram for explaining a method of adjusting the oscillation wavelength of the wavelength variable laser device.

Fig. 11 is a diagram for explaining a method of adjusting the oscillation wavelength of the wavelength variable laser device.

Fig. 12 is a flowchart showing an exemplary method of manufacturing the wavelength variable laser device according to embodiment 1 of the present invention.

Fig. 13A is a plan view showing a manufacturing process of the 2 nd semiconductor chip.

Fig. 13B is a cross-sectional view of fig. 13A taken along the line F-F and viewed in the direction of the arrow.

Fig. 14 is a plan view showing behavior of light when the wavelength variable laser device according to embodiment 2 of the present invention is operated.

Fig. 15 is a cross-sectional view showing a modification of the 1 st semiconductor chip.

(symbol description)

1. 301: a wavelength variable laser device; 2. 302: 1 st semiconductor chip; 3. 303: a 2 nd semiconductor chip; 4: an N-type substrate; 8: an N-type cladding layer; 9: an active layer; 10. 27: a passive layer; 11. 12: a P-type cladding layer; 13: a P-side electrode; 14: an N-side electrode; 15. 23, 25: a heater electrode; 16. 304: 1 st waveguide; 17. 305: a 2 nd waveguide; 18: a gain region; 19: 1 st reflection grating area; 20: a phase region; 21: a 2 nd reflective grating region; 22. 24, 26: a thin film heater; 28: a groove part; 29: a silicon substrate; 29 a: non-exposed regions (of the silicon substrate surface); 29 b: exposed regions (of the silicon substrate surface); 30: a laminate; 33: a silicon layer; 34: an optical circuit; 35: a grating coupler; 36: a single mode waveguide; 37: a spiral portion; 38-41: an electrode for power supply; 306: a 1 st gain region; 307: 1 st reflection grating area; 308: a phase region; 309: a 2 nd gain region; 310: a 2 nd reflective grating region; 311: an optical circuit; 312: a grating coupler; 313: a multimode interference coupler; 314: a single mode waveguide; 315: a spiral portion; 316: a 3 rd grating coupler; 317: a ring mirror.

Detailed Description

In order to make the description easy to understand, arrows indicating directions are described in the drawings, the X direction, the Y direction, and the Z direction are directions perpendicular to each other, and in the description, the X direction is sometimes referred to as a longitudinal direction, the Y direction is sometimes referred to as a width direction, and the Z direction is sometimes referred to as a height direction or a vertical direction.