CN107872005A - Silicon substrate hybrid integrated tunable laser and photon chip - Google Patents

Abstract

A silicon-based hybrid integrated tunable laser and a photonic chip, the laser includes a semiconductor optical amplifier, a silicon-based mode spot converter, a thermally tuned silicon-based ring resonator, a silicon-based phase shifter, and a dual-port silicon-based multiplexer arranged in sequence. mode interference mirror. The two-port silicon-based multimode interference mirror includes an input waveguide, an output waveguide, a multimode waveguide, and a tapered waveguide that connects the input waveguide, the output waveguide and one end of the multimode waveguide respectively, and the input waveguide is connected to the multimode waveguide. The output end of the thermally tunable silicon-based double-ring resonator, the other end of the multimode waveguide has two etching surfaces at a 45° angle to the axial direction of the waveguide, and the vertical intersection of the two etching surfaces is located in the multimode interference self On the axis of the imaging waveguide; the laser and other silicon-based functional devices form a photonic chip. The tunable laser and the photon chip of the invention have the advantages of small size and low cost, are easy to integrate, and have broad application prospects in the field of integrated optoelectronics and optical communication.

Description

Silicon-based hybrid integrated tunable laser and photonic chip

technical field

The invention relates to the technical field of semiconductor optoelectronic devices, in particular to a silicon-based hybrid integrated tunable laser light source and a photonic chip, which can be applied to fields such as optical interconnection, optical switching, and optical sensing.

Background technique

With the continuous improvement of people's requirements for information and communication, tunable lasers have gradually become an indispensable device in optical communication systems. It can not only be used as a backup light source in the wavelength division multiplexing system to save maintenance time and cost, but also can be used in any place where wavelength conversion is required in the communication system, such as data routing in the wavelength division multiplexing system, reconfigurable optical communication network, etc. There are many schemes for realizing tunable lasers, such as DBR semiconductor laser structure, DFB semiconductor laser, and surface-emitting laser. One of the important schemes is to combine a semiconductor optical amplifier chip with an external cavity feedback element to form an external cavity laser. Compared with traditional surface emitting lasers and distributed feedback lasers, external cavity tunable lasers can provide wider tuning range and narrower linewidth. However, traditional external cavity tunable lasers usually require bulky optical systems and mechanical control, and optical communication systems require small, low-cost tunable lasers.

Passive photonic integration technology can use micro-nano photonic structures to provide external feedback to III-V gain materials to achieve wavelength tuning. Among many photonic integration platforms, silicon photonic integration technology can make devices very compact and low cost due to its natural compatibility with CMOS process lines and the large refractive index difference between silicon and silicon dioxide. At present, a variety of silicon-based tunable lasers have been reported at home and abroad. These silicon-based tunable lasers include semiconductor optical amplifiers, phase shifters, double-ring resonators, and a ring mirror or Bragg mirror, and use end-face coupling or bonding Technology enables hybrid integration. The annular reflector in these silicon-based tunable laser structures adopts an annular structure, which requires a relatively large bending radius to reduce optical loss, so the size is relatively large; the Bragg reflector has high requirements on the process, and the reflectivity difference between different wavelengths is relatively large. , which is not conducive to realizing broadband tunability.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a silicon-based hybrid integrated tunable laser and photonic chip, in order to at least partially solve at least one of the above-mentioned technical problems.

To achieve the above object, the technical scheme of the present invention is as follows:

As an aspect of the present invention, a silicon-based hybrid integrated tunable laser is provided, including:

semiconductor optical amplifier;

A thermally tunable silicon-based ring resonator and a silicon-based phase shifter, wherein the thermally tunable silicon-based ring resonator is connected to the output end of the silicon-based phase shifter, and the silicon-based phase shifter is coupled to the semiconductor The output terminal of the optical amplifier;

A dual-port silicon-based multi-mode interference mirror is located at the output end of the thermally adjustable silicon-based double-ring resonator; wherein, the dual-port silicon-based multi-mode interference mirror includes an input waveguide, an output waveguide, a multi-mode waveguide, and A tapered waveguide connecting the input waveguide, the output waveguide and one end of the multimode waveguide, wherein:

the input waveguide is connected to the output of the thermally tunable silicon-based double-ring resonator,

The other end of the multimode waveguide that is not connected to the tapered waveguide has two etched surfaces at an angle of 45° to the axial direction of the waveguide, and the vertical intersection of the two etched surfaces is located on the axis of the multimode waveguide.

Preferably, the thermally tuned silicon-based ring resonator includes a first single-ring resonator and a second single-ring resonator connected in series, and the radii of the first single-ring resonator and the second single-ring resonator are different.

Preferably, both the first single-ring resonator and the second single-ring resonator include a ring-shaped silicon waveguide and a ring-shaped micro-heating electrode arranged above the ring-shaped silicon waveguide, and the material of the ring-shaped micro-heating electrode is selected from Ti, Au or TiN.

Preferably, the silicon-based phase shifter is a section of silicon waveguide above which a heating electrode is arranged.

Preferably, the silicon-based phase shifter is coupled to the semiconductor optical amplifier through an end face of a speckle converter, and the speckle converter is selected from an all-silicon-based speckle converter, or a silicon/nitride (oxygen) silicon material A speckle converter composed of, or a speckle converter composed of silicon/polymer materials.

Preferably, the semiconductor optical amplifier has a ridge structure, and the material is a semiconductor material transparent to the wavelength of silicon material, preferably GaAs-based, InP-based and GaSb-based quantum wells, quantum dots or nanowire materials.

Preferably, the end face of the output end of the semiconductor optical amplifier is coated with a dielectric film with a reflectivity less than 0.1%, and the other end face is coated with a dielectric film with a reflectance greater than 95%.

As another aspect of the present invention, a silicon-based hybrid integrated photonic chip is provided, including the above-mentioned silicon-based hybrid integrated tunable laser and other silicon-based functional devices, and the other silicon-based functional devices include One or more of a silicon-based grating coupler, a silicon-based modulator, a silicon-based detector, a silicon-based optical switching array, a silicon-based router, and a silicon-based optical switch at the output end of the multi-mode interference mirror.

Preferably, the silicon-based modulator is a Mach-Zehnder interferometer-type silicon-based modulator, or a ring resonator silicon-based modulator, and the silicon-based detector can be a silicon-based germanium detector, or a silicon-based III-V family of semiconductor detectors.

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. The silicon-based hybrid integrated tunable laser and photonic chip of the present invention can realize narrow-linewidth laser output through a high-Q thermally-tunable silicon-based ring resonator, and change the resonance of the ring resonator through the micro-heating electrode on it The condition realizes wavelength tunability, and the thermally tunable silicon-based ring resonator includes a first single-ring resonator and a second single-ring resonator connected in series with different ring radii, and the tuning range is large.

2. The silicon-based hybrid integrated tunable laser and photonic chip of the present invention utilizes a dual-port silicon-based multi-mode interference mirror structure, which can have little difference in light reflectivity and transmission rate in a large wavelength range; based on silicon-based The waveguide structure has the characteristics of small size, and the dual-port silicon-based multimode interference mirror of the present invention does not need additional structures such as other couplers to output laser light on the chip through the output waveguide, allowing the laser light to enter subsequent silicon-based functional devices , which is also beneficial for size reduction on the other hand.

3. The silicon-based hybrid integrated tunable laser and photonic chip of the present invention have the advantages of small size, low cost, easy integration, and broad application prospects in the field of integrated optoelectronics and optical communication. Moreover, the optical amplifier and the monolithic silicon-based photonic chip can be completed by means of the planarization process of the laser and the CMOS process line respectively, which guarantees the shape control of each part of the device.

Description of drawings

FIG. 1 is a schematic top view of a silicon-based hybrid integrated tunable laser and a photonic chip according to an embodiment of the present invention;

Fig. 2 is a three-dimensional structural diagram of a dual-port multimode interference mirror according to an embodiment of the present invention;

3 is a three-dimensional structural diagram of a thermally tunable silicon-based double-ring resonator and a silicon-based phase shifter according to an embodiment of the present invention;

Fig. 4 is the reflection and transmission diagram of the 1550nm band light field when the dual-port multimode interference mirror is working in Embodiment 1 of the present invention;

Fig. 5 is the selected spectrum diagram of the thermally tuned silicon-based double-ring resonator for 1550nm band light in Example 1 of the present invention;

FIG. 6 is a graph of wavelength tuning caused by every ten-degree increase in the temperature of the ring waveguide of the tunable laser in Embodiment 1 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Please refer to Figures 1-3, Figure 1 is a schematic structural view of a silicon-based hybrid integrated tunable laser and a photonic chip of the present invention, Figure 2 is a three-dimensional structural schematic view of a dual-port silicon-based multimode interference reflector of the present invention, and Figure 3 is A schematic diagram of the three-dimensional structure of the thermally tuned silicon-based double-ring resonator of the present invention. The silicon-based hybrid integrated tunable laser provided by the present invention includes: a semiconductor optical amplifier 1, a dual-port multi-mode interference mirror 2, a thermally tuned silicon-based double-ring resonator, a silicon-based phase shifter 3 and a mode spot converter 5. A 2-port silicon-based multimode interference mirror is used to solve the problem of light feedback and transmission, a thermally adjustable silicon-based double-ring resonator is used to realize wavelength selection, and a micro-heating electrode is used to realize wavelength tuning. The longitudinal mode of the resonator is matched with the wavelength selected by the thermally tuned silicon-based double-ring resonator by using the phase shift region. Finally, a broadband tunable silicon-based hybrid integrated tunable laser for photonic integrated chips is realized; compared with ring mirrors, multimode interference mirrors have the advantages of small size and wide reflection spectrum; compared with Bragg mirrors, Said that it has the advantages of low process requirements and insensitivity to wavelength; large tuning range, small size and low production cost can be achieved by using CMOS process. Among them, the semiconductor optical amplifier 1 is a gain semiconductor chip coated on both sides, adopting a ridge structure, and its material system can cover all semiconductor materials transparent to the wavelength of silicon materials, such as GaAs-based, InP-based and GaSb-based quantum wells, quantum dots and nanowire materials;

The output end of the semiconductor optical amplifier 1 is coupled through the mode spot converter, the thermally tuned silicon-based double-ring resonator and the silicon-based phase shifter 3 end faces, and the output end face of the silicon-based mode spot converter 5 is coated with high transmittance Dielectric film (reflectivity is usually less than 0.1%), and the other end is coated with a nearly total reflection dielectric film (reflectivity is greater than 95%).

The silicon-based mode spot converter 5 is a tapered waveguide to reduce the coupling loss of light from the semiconductor optical amplifier to the silicon waveguide, and can be made of an all-silicon-based mode spot converter or silicon/nitride (oxygen) silicon material The speckle converter, or the speckle converter composed of silicon/polymer material, is used to reduce the loss caused by coupling the light of the semiconductor optical amplifier into the silicon waveguide.

The thermally adjustable silicon-based double-ring resonator and the silicon-based phase shifter 3 are composed of two single-ring resonators 3.1 with different radii, a silicon-based phase shifter 3.2, and an annular micro-heating electrode 3.3.

The two single-ring resonators 3.1 include a ring-shaped silicon waveguide and a ring-shaped micro-heating electrode 3.3 arranged above it, connected in series, and the radii of the two rings are different, thereby realizing a large tuning range. It is easy to understand that a single-ring resonator can also be used for wavelength tuning, but the tuning range is smaller than that of a double-ring resonator. The silicon-based phase shifter 3.2 refers to a section of silicon waveguide covered with heating electrodes. The annular micro-heating electrode 3.3 has the same shape as the annular silicon waveguide below it, with a slightly wider width. Micro-heating electrode materials are metals such as TiAu, or nitrides such as TiN.

The dual-port silicon-based multimode interference mirror 2 is connected to the thermally adjustable silicon-based double-ring resonator and the output end of the silicon-based phase shifter 3, which is composed of an input/output waveguide 2.1, a tapered waveguide 2.2 and a multimode interference self-imaging waveguide 2.3 , the input waveguide and the output waveguide are respectively connected to the multi-mode interference self-imaging waveguide 2.3 through a tapered waveguide 2.2;

Among them, the dual-port silicon-based multi-mode interference mirror 2 uses two single-mode waveguides as the input and output waveguides 2.1 respectively; the multi-mode interference self-imaging waveguide 2.3 is a wide waveguide, and the side away from the tapered waveguide 2.2 is etched into two The etched sections are perpendicular to each other and 45° to the direction of the waveguide, and the intersection of the two sections is located in the center of the waveguide. The total reflection of light and the principle of self-imaging are used to realize the reflection of light, the number of imaging spots and the length of the wide waveguide related. Structurally, the dual-port silicon-based multimode interference mirror 2 can be regarded as half of the dual-port MMI. The two 45° etched surfaces are used to achieve total reflection and transfer the imaging spot to the original position of the input and output waveguides. , compared with directly etching a vertical section, it can reduce the loss.

The output waveguide 2.1 of the dual-port silicon-based multimode interference mirror 2 can be connected to other silicon-based functional devices 4. The silicon-based hybrid integrated tunable photonic laser and other silicon-based functional devices 4 form a silicon-based hybrid integrated tunable photonic chip.

Other silicon-based functional devices 4 include silicon-based grating couplers, silicon-based modulators, silicon-based detectors, silicon-based optical switching arrays, silicon-based routers, or silicon-based optical switches. The other silicon-based functional devices are based on different It needs to be selected to face the application of optoelectronic integration with different functions. For example, the silicon-based grating coupler can be used as a device performance test port, or it can be a fiber-coupled output port; where the silicon-based modulator can be a Mach-Zehnder interferometer type A silicon-based modulator, or a ring resonator silicon-based modulator; the silicon-based detector may be a silicon-based germanium detector, or a silicon-based III-V semiconductor detector.

The above-mentioned silicon-based multimode interference mirror 2, thermally tuned silicon-based double-ring resonator and silicon-based phase shifter 3, other silicon-based functional devices 4, and silicon-based mode spot converter 5 form a monolithic silicon-based photonic chip 6, The material basis of the monolithic silicon-based photonic chip 6 is a silicon-on-insulator SOI material, and the SOI technology is relatively mature. The structure of the SOI material is to introduce a layer of buried oxide layer 8 between the top layer of silicon and the silicon substrate 7, thereby The light wave transmitted in the upper waveguide is completely isolated from the substrate to eliminate the absorption of the substrate. The monolithic silicon-based photonic chip can be manufactured by introducing growth and etching heating electrodes with the help of a CMOS process platform to achieve mass production. The semiconductor optical amplifier is manufactured by two photolithography and coating, the first photoetching the ridge waveguide of the optical amplifier, and then growing a layer of electrically isolated SiO ₂ by PECVD (plasma enhanced chemical vapor deposition method), and the second The electrical injection window is carved out by secondary photolithography, then the front electrode is grown, the back electrode is grown after thinning and polishing, and the coating is finally cleaved. The preparation process is simple, and the coupling problem between the semiconductor optical amplifier and the silicon waveguide is conveniently solved.

When in use, the light amplified and output by the semiconductor optical amplifier is coupled into the silicon waveguide through the silicon-based mode spot converter, and a specific wavelength is selected through the thermally tuned double-ring resonator and the phase shifter, and partially reflected at the multi-mode interference mirror to realize optical The feedback amplification part enters the subsequent silicon-based functional device through the output waveguide.

The silicon-based hybrid integrated tunable laser and photonic chip described in the present invention have a working wavelength range covering more than 1.1 microns to near-infrared, mid-to-far infrared.

A silicon-based hybrid integrated tunable laser for photonic integrated chips provided by the present invention will be further described below in conjunction with specific embodiments.

Example 1

In this embodiment, the semiconductor optical amplifier adopts the commercial 1550nm epitaxial material based on indium phosphide, and is manufactured into a single transverse mode optical amplifier through steps such as photolithography; the dual-port multimode interference mirror and the thermally tuned silicon base The double-ring resonators are all made of 220nm SOI material, the etching depth is 220nm, and the width of the tapered waveguide gradually changes from 400nm to 1.8μm; the length of the dual-port multimode interference self-imaging area is about 22μm, and the perimeters of the two rings are respectively 186 μm and 169 μm. Figure 4 is the light field distribution diagram of the dual-port silicon-based multimode interference mirror. It can be seen that most of the light field is localized in the device to realize light reflection and transmission functions, and the light loss is relatively small. Figure 5 shows the light reflection and transmission spectrum corresponding to the dual-port silicon-based multimode interference mirror. It can be seen that the reflector is not very sensitive to the wavelength of light, and the loss is relatively low. Fig. 6 is a transmission spectrum diagram of a thermally tuned silicon-based double-ring resonator. The light from the semiconductor optical amplifier on the right selects the wavelength in the thermally tunable silicon-based double-ring resonator, and then forms feedback and output on the multi-mode interference reflector, realizing the function of a silicon-based hybrid integrated tunable laser.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (9)

1. A silicon-based hybrid integrated tunable laser, characterized in that, comprising: semiconductor optical amplifier; A thermally tunable silicon-based ring resonator and a silicon-based phase shifter, wherein the thermally tunable silicon-based ring resonator is connected to the output end of the silicon-based phase shifter, and the silicon-based phase shifter is coupled to the semiconductor The output terminal of the optical amplifier; A dual-port silicon-based multi-mode interference mirror is located at the output end of the thermally adjustable silicon-based double-ring resonator; wherein, the dual-port silicon-based multi-mode interference mirror includes an input waveguide, an output waveguide, a multi-mode waveguide, and A tapered waveguide connecting the input waveguide, the output waveguide and one end of the multimode waveguide, wherein: the input waveguide is connected to the output of the thermally tunable silicon-based double-ring resonator, The other end of the multimode waveguide that is not connected to the tapered waveguide has two etched surfaces at an angle of 45° to the axial direction of the waveguide, and the vertical intersection of the two etched surfaces is located on the axis of the multimode waveguide. 2. The silicon-based hybrid integrated tunable laser according to claim 1, wherein the thermally tunable silicon-based ring resonator comprises a first single-ring resonator and a second single-ring resonator connected in series, and the first The radii of the first single-loop resonator and the second single-loop resonator are different. 3. The silicon-based hybrid integrated tunable laser according to claim 2, wherein the first single-ring resonator and the second single-ring resonator both comprise a ring silicon waveguide and a ring silicon waveguide arranged above the ring silicon waveguide. An annular micro-heating electrode, wherein the material of the annular micro-heating electrode is selected from Ti, Au or TiN. 4 . The silicon-based hybrid integrated tunable laser according to claim 1 , wherein the silicon-based phase shifter is a section of silicon waveguide with a heating electrode above it. 5. The silicon-based hybrid integrated tunable laser according to claim 1, wherein the silicon-based phase shifter is coupled to the semiconductor optical amplifier through the end face of a speckle converter, and the speckle converter is selected from An all-silicon-based speckle transformer, or a speckle transformer composed of silicon/silicon nitride (oxygen) material, or a speckle transformer composed of silicon/polymer material. 6. The silicon-based hybrid integrated tunable laser according to claim 1, wherein the semiconductor optical amplifier is a ridge structure, and the material is a semiconductor material transparent to the wavelength of silicon material, preferably GaAs base, InP base and GaSb based quantum well, quantum dot or nanowire material. 7. The silicon-based hybrid integrated tunable laser according to claim 1, characterized in that, the output end face of the semiconductor optical amplifier is coated with a dielectric film with a reflectivity less than 0.1%, and the other end face is coated with a dielectric film with a reflectivity greater than 0.1%. 95% dielectric film. 8. A silicon-based hybrid integrated photonic chip, characterized in that it comprises the silicon-based hybrid integrated tunable laser and other silicon-based functional devices as claimed in any one of claims 1-7, said other silicon-based functional devices One or more of silicon-based grating couplers, silicon-based modulators, silicon-based detectors, silicon-based optical switching arrays, silicon-based routers, and silicon-based optical switches arranged at the output end of the silicon-based multimode interference mirror kind. 9. A kind of silicon-based hybrid integrated photonic chip according to claim 8, characterized in that, the silicon-based modulator is a Mach-Zehnder interferometer type silicon-based modulator or a ring resonator silicon-based modulator, the The silicon-based detector is a silicon-based germanium detector or a silicon-based III-V semiconductor detector.