Multifunction reconfigurable hybrid integrated laser

Abstract

The application provides a multifunctional reconfigurable hybrid integrated laser, comprising: a gain chip 1 and a silicon-based chip 2; the gain chip 1 and the silicon-based chip 2 are hybrid integrated through edge coupling; the gain chip 1 is used as an optical gain unit to output wide-spectrum spontaneous emission light; and the silicon-based chip 2 is used as a filtering and tuning unit to construct a laser resonant cavity to realize laser output and laser wavelength tuning. The application is integrated as a whole into a hybrid integrated module, multifunctional reconfiguration of output laser is realized, and the application can be applied to different application scenarios such as wavelength division multiplexing and laser radar.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically to a multifunctional reconfigurable hybrid integrated laser, and more specifically to a multifunctional reconfigurable hybrid integrated laser that integrates silicon photonics with III-V group materials. Background Technology

[0002] The demand for lasers is constantly increasing in fields such as optical interconnection, optical transmission, lidar, optical sensing, and spectral analysis. Common lasers can be divided into solid-state lasers, fiber lasers, and semiconductor lasers. Among them, semiconductor lasers have the characteristics of small size, low power consumption, narrow spectral width, low cost, and mass production capability.

[0003] With the rapid development of silicon-based optoelectronics, the on-chip and integration of semiconductor lasers has become a new research hotspot. Since silicon is an indirect bandgap material with low spontaneous emission efficiency, it is difficult to achieve high-efficiency gain based on silicon itself. Therefore, silicon-based integrated lasers often use traditional III-V group direct bandgap materials and other methods to achieve laser emission through integration and packaging.

[0004] From an integration perspective, there are three main methods for integrating III-V group materials with silicon: heterogeneous integration, epitaxial growth, and hybrid integration. While epitaxial growth and heterogeneous integration have been achieved and align with the future trend of large-scale 3D integration, they have high technical requirements and face challenges in process compatibility, yield, and heat dissipation. Currently, hybrid integration remains the most mature method. Hybrid integration couples a pre-formed III-V group chip with a silicon-based external cavity to form a hybrid cavity laser. This method offers the following advantages: 1. Current coupling technology is very mature, allowing for large-scale manufacturing and production. 2. The active and passive regions are separated, facilitating thermal management. 3. The gain and external cavity components can be designed and optimized independently, enabling both components to achieve optimal performance simultaneously, thereby improving laser performance.

[0005] Currently, most laser designs focus on optimizing a single function, typically developing and applying them around specific wavelengths, power levels, modes, or modulation methods. While this single-function approach has advantages in certain applications, with technological advancements and the diversification of application requirements, single-function lasers are increasingly unable to meet the demands of increasingly complex environments. For example, lidar systems increasingly require continuously tunable sweep lasers to acquire more accurate environmental information at different detection distances and angles, while free-space optical communication typically demands lasers with stable single-wavelength output to ensure efficient communication links. Given these diverse needs, overcoming the design bottlenecks of traditional lasers and developing multifunctional, reconfigurable lasers is of significant research importance and application value.

[0006] The core advantage of multifunctional reconfigurable lasers lies in their ability to switch and adjust different functions through external control or intelligent design without altering the device structure. These lasers possess extremely high flexibility and adaptability, dynamically adjusting their output characteristics, such as wavelength, frequency, output power, and laser mode, according to different application requirements. This control method not only overcomes the limitations of fixed functions in traditional lasers but also enables them to realize greater potential in a variety of complex working environments.

[0007] Patent document CN114583541A (application number: 202210220370.0) discloses a hybrid integrated laser, comprising: an optical gain region, a first optical reflector, a second optical reflector, and a phase region; the optical gain region is disposed on a first chip and includes a semiconductor optical amplification element; the first optical reflector is integrated on a second chip, and the second optical reflector is integrated on either the first or second chip; the first optical reflector, the second optical reflector, and the optical waveguide circuit between them constitute the optical resonant cavity of the hybrid integrated laser; both the optical gain region and the phase region are located within the optical resonant cavity; the second optical reflector includes a Sagnac reflector or a reflective end face disposed on the waveguide in the semiconductor optical amplification element; thereby realizing a narrow-linewidth semiconductor laser while ensuring that the narrow-linewidth semiconductor laser has low process difficulty and manufacturing cost, and on this basis, it can further realize high-speed modulation of the laser with large bandwidth and tunable chirp, meeting the application requirements of medium and long-distance optical communication. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the purpose of this invention is to provide a multifunctional reconfigurable hybrid integrated laser.

[0009] A multifunctional reconfigurable hybrid integrated laser according to the present invention includes: a gain chip 1 and a silicon-based chip 2;

[0010] The gain chip 1 and the silicon-based chip 2 are hybrid integrated through edge coupling;

[0011] The gain chip 1 serves as an optical gain unit, used to output broadband spontaneous emission light;

[0012] The silicon-based chip 2 serves as a filtering and tuning unit, used to construct a laser resonant cavity and achieve tuning of laser output and laser wavelength.

[0013] Preferably, the gain chip 1 includes: a high-reflectivity end face 11, an anti-reflection end face 12, and a gain waveguide 13;

[0014] The gain waveguide 13 is located between the high-reflection end face 11 and the anti-reflection end face 12;

[0015] The high-reflectivity end face 11 is coated with a high-reflectivity film with a reflectivity higher than 90%.

[0016] The anti-reflective end face 12 is coated with an anti-reflection film, and its reflectivity is less than 5%.

[0017] The gain waveguide 13 is tilted at a preset angle to reduce end-face reflection.

[0018] Preferably, the silicon-based chip 2 includes: a mode converter 21, a thermal phase shifter 22, a cascaded microring 23, a mirror 24, and a coupler 25;

[0019] The speckle converter 21 is connected to the output terminal of the gain chip 1;

[0020] The speckle converter 21, the thermal phase shifter 22, the cascaded microring 23, the reflector 24, and the coupler 25 are connected in sequence;

[0021] The mode field converter 21 is used to match the mode field in the gain chip 1 with the mode field in the silicon-based chip 2;

[0022] The thermal phase shifter 22 is used to adjust the position of the longitudinal mode of the cavity resonance, so that the cavity resonance and the micro-ring resonance are aligned, thereby achieving thermal tuning;

[0023] The cascaded micro-ring 23 is used as a frequency selective filter to select a mode that meets preset requirements from a series of longitudinal modes generated by the resonant cavity oscillation.

[0024] The reflector 24 is an on-chip structure with controllable reflectivity and transmittance;

[0025] The coupler 25 is used to couple the laser output.

[0026] Preferably, the high-reflectivity end face 11 of the gain chip 1 and the reflector 24 of the silicon-based chip 2 constitute the resonant cavity mirror of the laser.

[0027] Preferably, the mode converter 21 is an end-face coupler composed of an inverted conical waveguide, wherein the inverted conical waveguide is tilted at a certain angle to match the output angle of the gain chip 1.

[0028] Preferably, the reflector 24 includes a Sagnac reflector;

[0029] The Sagnac reflector includes: an input waveguide, an output waveguide, a 2×2 multimode interferometer 241, a thermal phase shifter 243, and a loop 242;

[0030] The input waveguide and the output waveguide are respectively connected to the two input terminals of the 2×2 multimode interferometer 241 to form a loop; the thermal phase shifter 243 is connected in series on the loop to adjust the reflectivity of the mirror.

[0031] Preferably, the cascaded microring 23 is composed of two Euler-bent microrings of the same size cascaded together;

[0032] The Euler-curved microring uses a straight waveguide track; heating electrodes are provided above the uncoupled region of the Euler-curved microring to adjust the frequency-selective output wavelength of the cascaded microring.

[0033] Preferably, four-wavelength filtering in the C-band is achieved by setting the size of the Euler-bent microring in the cascaded microring 23; and four-wavelength output is achieved by adjusting the thermal phase shifter 22 to align the longitudinal mode of the cavity resonator with the microring resonator.

[0034] Euler's formula for curvature is:

[0035] k(s)=1 / R(s)=k0+α·s

[0036] Where: k(s) is the curvature at path s, R(s) is the radius of curvature at path s, α is the rate of change of curvature; k0 is the curvature at the starting point;

[0037] Where, k0 = 1 / R max k1 = 1 / R min ; α=(k1-k0) / L; R max R is the maximum radius; min L is the minimum radius; L is the path length.

[0038] Preferably, by applying a voltage to the heating electrode of one of the Euler-bent microrings in the cascaded microrings 23 to generate a vernier effect, the FSR of the cascaded microrings 23 increases, thereby achieving single-wavelength output in the C-band.

[0039] Preferably, by applying the same voltage to the heating electrodes of the two Euler-bent microrings in the cascaded microrings 23, the single-wavelength resonant peak of the microrings is shifted by utilizing the thermo-optic effect of silicon, and the thermal phase shifter 22 is synchronously adjusted to match the cavity resonance with the microring resonance, thereby achieving single-wavelength mode-skipping frequency sweep.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. This invention can achieve functions such as single-wavelength output, wavelength tunable, and multi-wavelength output through adjustment;

[0042] 2. This invention designs two identical Euler-bent microrings cascaded together. The size of the Euler-bent microrings enables four-wavelength filtering in the C-band, with an FSR (Free Spectral Range) of 20 nm. By adjusting the thermal phase shifter to align the longitudinal mode of the cavity resonance with the microring resonance, four-wavelength output is achieved. By applying a voltage to the heating electrode of one of the microrings to generate a vernier effect, the FSR of the cascaded microrings increases, achieving single-wavelength output in the C-band. Furthermore, by applying the same voltage to both microrings in this state, the thermo-optical effect of silicon is used to shift the single-wavelength resonant peak of the microrings. The thermal phase shifter is then adjusted synchronously to match the cavity resonance with the microring resonance, thereby achieving single-wavelength mode-skipping frequency sweep.

[0043] 3. The present invention is integrated into a single chip, achieving multi-functional reconfigurability, and can be applied to different application scenarios such as coarse wavelength division multiplexing and lidar. Attached Figure Description

[0044] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0045] Figure 1 This is a schematic diagram of a two-dimensional cross-section (xy) of the hybrid integrated laser of the present invention.

[0046] Figure 2 This is a schematic diagram of a two-dimensional cross-section (yz) of the silicon-based chip of the hybrid integrated laser of the present invention.

[0047] Figure 3 This is a schematic diagram of the hybrid integrated laser packaging of the present invention.

[0048] Figure 4 This is a schematic diagram of the two-dimensional cross-section (xy) structure and mode field evolution diagram of the hybrid integrated laser mode converter of the present invention.

[0049] Figure 5 The four-wavelength transmission spectrum is the simulation prediction of the hybrid integrated laser microring of this invention.

[0050] Figure 6 The single-wavelength transmission spectrum is the simulation prediction of the micro-ring of the hybrid integrated laser of this invention.

[0051] Among them, 1-gain chip; 2-silicon-based chip; 11-high-reflectivity end face; 12-anti-reflection end face; 13-gain waveguide; 21-mode converter; 22-thermal phase shifter; 23-cascaded microring; 24-mirror; 25-coupler; 231-first Euler-bent microring; 232-second Euler-bent microring; 241-2×2 multimode interferometer; 242-loop; 243-thermal phase shifter; 100-multifunctional reconfigurable hybrid integrated laser; 3- Aluminum base; 4-Copper heat sink; 5-PCB; 100-Multifunctional reconfigurable hybrid integrated laser; 26-Silicon substrate; 27-Silicon dioxide lower cladding; 28-Silicon on insulator; 29-Silicon dioxide upper cladding; 221-First TiN heater; 233-Second TiN heater; 234-Third TiN heater; 222-First through-hole connection metal; 235-Second through-hole connection metal; 236-Third through-hole connection metal. Detailed Implementation

[0052] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0053] Example 1

[0054] A multifunctional reconfigurable hybrid integrated laser provided by the present invention, such as Figure 1 As shown, it includes: a III-V group material gain chip 1 and a silicon-based chip 2; the gain chip 1 and the silicon-based chip 2 are optically coupled in the form of edge coupling;

[0055] The gain chip 1 includes a high-reflection end face 11, an anti-reflection end face 12, and a gain waveguide 13 located between the high-reflection end face 11 and the anti-reflection end face 12.

[0056] The high-reflectivity end face 11 of the gain chip 1 and the reflector 24 of the silicon-based chip 2 constitute the resonant cavity mirror of the laser.

[0057] The gain chip 1 is used to generate an amplified spontaneous emission spectrum under electric pumping, which oscillates in the resonant cavity of the laser, and multi-beam interference generates a series of longitudinal modes.

[0058] Furthermore, the pump current of the gain chip 1 is input from an external device. The high-reflectivity end face 11 of the gain chip 1 is coated with a high-reflectivity film with a reflectivity higher than 90%; the anti-reflection end face 12 is coated with an anti-reflection film with a reflectivity lower than 5%; the gain waveguide 13 can be tilted by 20 degrees to reduce end face reflection.

[0059] The silicon-based chip 2 includes, in sequence, a speckle converter 21, a thermal phase shifter 22, a cascaded micro-ring 23, a reflector 24, and a coupler 25.

[0060] The mode field converter 21 is used to match the mode field in the gain chip 1 with the mode field in the silicon-based chip 2;

[0061] The cascaded micro-ring 23 is used as a frequency selective filter to select a specific mode from a series of longitudinal modes generated by the resonant cavity oscillation;

[0062] The thermal phase shifter 22 is used to adjust the position of the longitudinal mode of the cavity resonance so that the cavity resonance and the micro-ring resonance are aligned.

[0063] The coupler 25 is used to couple the laser output; in this embodiment, the coupler 25 can be a grating coupler or a horizontal end face coupler; when a grating coupler is used, the laser is vertically coupled out through the grating coupler.

[0064] The mode converter 21 is an end-face coupler composed of an inverted conical waveguide, which is tilted at a certain angle to match the output angle of the gain chip 1; in this embodiment, the tilt angle can be 17 degrees.

[0065] Furthermore, the cascaded microring 23 is composed of two Euler-bent microrings of the same size, such as... Figure 1 As shown, a first Euler-bent microring 231 and a second Euler-bent microring 232 are used; a straight waveguide raceway is employed to improve coupling efficiency. Heating electrodes are positioned above the uncoupled regions of both microrings to adjust the frequency-selective output wavelength of the cascaded microrings. The size of the Euler-bent microrings enables four-wavelength filtering output in the C-band, with an FSR (free spectral range) of 20 nm. By applying a voltage to the heating electrode of the first Euler-bent microring 231, a vernier effect is generated, increasing the FSR of the cascaded microrings and achieving single-wavelength output in the C-band. Further applying the same voltage to both microrings in this state, the thermal phase shifter 22 is synchronously adjusted to achieve single-wavelength mode-skipping-free frequency sweep.

[0066] Furthermore, the reflector 24 is an on-chip structure with controllable reflectivity and transmittance. The reflector 24 can be a Sagnac reflector structure, consisting of an input waveguide, an output waveguide, a 2×2 multimode interferometer, and a loop connected in series with a heat-shifting phase shifter. The input waveguide and the output waveguide are respectively connected to the two input terminals of the 2×2 multimode interferometer, and the two output terminals of the 2×2 multimode interferometer are connected in a loop. The loop is connected in series with a heat-shifting phase shifter for adjusting the reflectivity of the reflector.

[0067] Example 2

[0068] Example 2 is a preferred example of Example 1.

[0069] A multifunctional reconfigurable hybrid integrated laser 100 provided by the present invention, such as Figure 2 As shown, the schematic diagram of the two-dimensional cross-section (yz) of the silicon-based chip of the hybrid integrated laser of the present invention, from bottom to top, consists of a silicon substrate 26, a silicon dioxide lower cladding layer 27, a silicon-on-insulator layer 28, and a silicon dioxide upper cladding layer 29, etched layer by layer; a first TiN heater 221, a second TiN heater 233, and a third TiN heater 234 are respectively disposed above the thermal phase shifter 22 and the cascaded microring 23. The first TiN heater 221, the second TiN heater 233, and the third TiN heater 234 are connected to metal 222 through a first through-hole, to metal 235 through a second through-hole, and to metal 236 through a third through-hole, respectively. The thermal phase shifter 22, through the thermal adjustment of the heaters, changes the position of the entire cavity resonance peak, aligning it with the microring resonance.

[0070] Example 3

[0071] Example 3 is a preferred example of Example 1.

[0072] A multifunctional reconfigurable hybrid integrated laser 100 provided by the present invention, such as Figure 3 The diagram shows a schematic of the hybrid integrated laser package of the present invention. The gain chip 1 is mounted on a copper heat sink 4, and both the gain chip 1 and the silicon-based chip 2 are mounted on a common aluminum substrate 3. The gain waveguide of the gain chip 1 and the mode converter of the silicon-based chip are horizontally aligned. The laser is controlled by a PCB (printed circuit board) 5 attached to the aluminum substrate 3, and the PCB 5 is tightly connected to the aluminum substrate 3.

[0073] Example 4

[0074] Example 4 is a preferred example of Example 1.

[0075] A multifunctional reconfigurable hybrid integrated laser 100 provided by the present invention, such as Figure 4The diagram shows a two-dimensional cross-sectional (xy) structural schematic and mode field evolution diagram of the mode converter 21 in one embodiment of the hybrid integrated laser of the present invention. The mode converter 21 on the silicon-based chip 2 is an end-face coupler composed of an inverted conical waveguide. Its function is to convert the large-sized mode output from the gain chip 1 into a small-sized mode in the single-mode waveguide of the silicon-based chip 2, and then transmit it in the silicon-based waveguide. The wide end width of the mode converter 21 is the same as the width of the silicon-based single-mode waveguide, both being 500 nm; the narrow end width of the mode converter 21 is 100 nm. The inverted conical waveguide is tilted at 17° to match the output angle of the gain chip 1.

[0076] In this embodiment, the mode converter can be selected from any one of the following: a nonlinear profile inverted conical side coupler, a multi-tooth conical side coupler, or a side coupler based on a sub-wavelength grating structure.

[0077] Example 5

[0078] Example 5 is a preferred example of Example 1.

[0079] A multifunctional reconfigurable hybrid integrated laser 100 provided by the present invention, such as Figure 5 As shown, the four-wavelength transmission spectrum predicted by simulation of the hybrid integrated laser microring of this invention. The specific implementation methods for the four wavelengths include:

[0080] 1) Establish an Euler-bent microring model with a waveguide width of 500 nm, a distance of 200 nm between the straight waveguide and the microring, and a straight waveguide raceway length of 1.85 μm on the microring. The two Euler-bent microrings are identical in size and structure.

[0081] 2) The required microring structure parameters for four-wavelength output were determined by scanning the maximum and minimum radii of the Euler bend. The maximum Euler bend radius was determined to be 543.4 μm and the minimum Euler bend radius was determined to be 2 μm.

[0082] Example 6

[0083] Example 6 is a preferred example of Example 1.

[0084] A multifunctional reconfigurable hybrid integrated laser 100 provided by the present invention, such as Figure 6 As shown, the single-wavelength transmission spectrum predicted by simulation of the hybrid integrated laser microring of this invention. The single-wavelength implementation specifically includes:

[0085] 1) Establish a thermal simulation model of Euler bending microrings, scan the input power of the heater above the uncoupled region of a single microring, and generate the three-dimensional temperature field distribution of the cascaded microrings under different input powers.

[0086] 2) By importing the temperature field distribution results into the optical model, cascaded micro-ring transmission spectra under different input powers can be generated sequentially, resulting in a schematic diagram of the single-wavelength output transmission spectrum. Figure 6 The input power corresponding to the four-wavelength to single-wavelength switching is 16mW. With the same input power applied to the heaters above the uncoupled regions of the two microrings, the single-wavelength transmission line shifts to the right, and the calculated single-wavelength tuning rate is 0.62nm / mW.

[0087] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A multifunctional reconfigurable hybrid integrated laser, characterized in that, include: Gain chip (1) and silicon-based chip (2); The gain chip (1) and the silicon-based chip (2) are hybrid integrated through edge coupling; The gain chip (1) serves as an optical gain unit for outputting broadband spontaneous emission light; The silicon-based chip (2) serves as a filtering and tuning unit, used to construct a laser resonant cavity and achieve tuning of laser output and laser wavelength; The silicon-based chip (2) includes: a speckle converter (21), a thermal phase shifter (22), a cascaded microring (23), a mirror (24), and a coupler (25); The speckle converter (21) is connected to the output terminal of the gain chip (1); The speckle converter (21), the thermal phase shifter (22), the cascaded microring (23), the reflector (24), and the coupler (25) are connected in sequence; The mode field converter (21) is used to match the mode field in the gain chip (1) and the mode field in the silicon-based chip (2); The thermal phase shifter (22) is used to adjust the position of the longitudinal mode of the cavity resonance, so that the cavity resonance and the micro-ring resonance are aligned, thereby achieving thermal tuning; The cascaded micro-ring (23) is used as a frequency selective filter to select a mode that meets the preset requirements from a series of longitudinal modes generated by the resonant cavity oscillation; The reflector (24) is an on-chip structure with controllable reflectivity and transmittance; The coupler (25) is used to couple the laser output; The reflector (24) includes: a Sagnac reflector; The Sagnac reflector includes: an input waveguide, an output waveguide, and... Multimode interferometer (241), thermal phase shifter (243), and loop (242); The input waveguide and the output waveguide are respectively connected to the The two input terminals of the multimode interferometer (241) are connected to form a loop; the thermal phase shifter (243) is connected in series on the loop to adjust the reflectivity of the mirror; The cascaded microring (23) is composed of two Euler-bent microrings of the same size cascaded together; The Euler-curved microring uses a straight waveguide track; heating electrodes are provided above the uncoupled region of the Euler-curved microring to adjust the frequency-selective output wavelength of the cascaded microring; By setting the size of the Euler-bent microring in the cascaded microring (23), four-wavelength filtering in the C-band is achieved; by adjusting the thermal phase shifter (22) to align the longitudinal mode of the cavity resonance with the microring resonance, four-wavelength output is achieved. Euler's formula for curvature is: in: Let be the curvature at path s. Let be the radius of curvature at path s. The rate of change of curvature; The curvature at the starting point; in, ; ; ; The maximum radius; Minimum radius; This represents the path length. By applying a voltage to the heating electrode of one of the Euler-bent microrings in the cascaded microrings (23) to generate a vernier effect, the FSR of the cascaded microrings (23) increases, thereby achieving single-wavelength output in the C-band. By applying the same voltage to the heating electrodes of the two Euler-bent microrings in the cascaded microrings (23), the single-wavelength resonant peak of the microrings is shifted by utilizing the thermo-optic effect of silicon. The thermal phase shifter (22) is then adjusted synchronously to match the cavity resonance with the microring resonance, thereby achieving single-wavelength mode-skipping frequency sweep.

2. The multifunctional reconfigurable hybrid integrated laser according to claim 1, characterized in that, The gain chip (1) includes: a high-reflection end face (11), an anti-reflection end face (12), and a gain waveguide (13). The gain waveguide (13) is located between the high-reflection end face (11) and the anti-reflection end face (12); The high-reflectivity end face (11) is coated with a high-reflectivity film with a reflectivity of over 90%. The anti-reflective end face (12) is coated with an anti-reflective film with a reflectivity of less than 5%; The gain waveguide (13) is tilted at a preset angle to reduce end face reflection.

3. The multifunctional reconfigurable hybrid integrated laser according to claim 1, characterized in that, The high-reflectivity end face (11) of the gain chip (1) and the reflector (24) of the silicon-based chip (2) constitute the resonant cavity mirror of the laser.

4. The multifunctional reconfigurable hybrid integrated laser according to claim 1, characterized in that, The mode converter (21) is an end-face coupler composed of an inverted conical waveguide, which is tilted at a certain angle to match the output angle of the gain chip (1).

Images