Laser based on bimetallic Bragg grating and top surface HR reflecting film

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on a bimetallic Bragg grating and a top surface HR reflecting film, which comprises a gain chip, a first high-reflection HR film is plated on the left end surface of the gain chip, and a first anti-reflection AR film is plated on the right end surface of the gain chip. A metal Bragg grating waveguide is arranged on the right side of the gain chip, an annular resonance optical waveguide is arranged on the front side of the ridge optical waveguide, the right end face of the gain chip and the left end face of the metal Bragg grating waveguide are aligned and attached to form an outer cavity structure, and the left end face of the metal Bragg grating waveguide is plated with a second anti-reflection AR film. The right end face of the metal Bragg grating waveguide is plated with a third anti-reflection AR film. Performance test is carried out on the laser provided by the invention, and test results show that the line width is 0.6 kHz, the SMSR is 63dB, and the threshold current is 22mA, thereby verifying the effectiveness of the laser provided by the invention.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically to a laser based on a bimetallic Bragg grating and a top-surface HR reflective film. Background Technology

[0002] With the rapid development of optoelectronic technology, fields such as quantum key distribution, coherent optical communication, high-precision spectral analysis, and photonic integrated chips place extremely stringent demands on laser performance, while cost control has also become a critical factor. However, traditional distributed feedback (DFB) lasers and conventional external cavity lasers face numerous challenges in practical applications:

[0003] 1. Traditional external cavity lasers mostly employ a single-grating structure, with a side-mode rejection ratio (SMSR) of only 45-50 dB and a linewidth of approximately 20-50 kHz (IEEE Photonics Technology Letters, 2020), which cannot meet the stringent requirements of high-precision applications. Balancing beam quality and integration is difficult, relying on complex optical alignment processes, increasing production difficulty and cost, and hindering large-scale integrated manufacturing. Furthermore, traditional external cavity lasers cannot effectively address the upward diffraction energy loss caused by the grating structure, affecting the light guiding performance of the grating waveguide.

[0004] 2. Due to carrier density fluctuations and the typical 0.5mm lasing cavity length, the linewidth of DFB lasers is usually between 1-10MHz (Optics Express, 2021). In applications such as coherent detection, a wider linewidth can lead to severe signal interference, significantly reducing detection accuracy and system performance. Its secondary epitaxial process is complex, with a yield of only 65-70% (Photonics Research, 2021), and manufacturing costs are 2-3 times higher than external cavity lasers. The reflectivity of semiconductor gratings is only 93-95%, requiring additional gain compensation, which increases power consumption by 15-20% and also causes heat dissipation problems, affecting the stability and reliability of the laser. Summary of the Invention

[0005] This invention provides a laser based on a bimetallic Bragg grating and a top-surface HR reflective film to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a laser based on a bimetallic Bragg grating and a top surface HR reflective film, comprising: a gain chip, wherein a first high reflectivity HR film is deposited on the left end face of the gain chip, and a first antireflection AR film is deposited on the right end face of the gain chip.

[0007] A metal Bragg grating waveguide is disposed on the right side of the gain chip. The right end face of the gain chip is aligned and bonded with the left end face of the metal Bragg grating waveguide to form an external cavity structure. A second anti-reflection AR film is deposited on the left end face of the metal Bragg grating waveguide, and a third anti-reflection AR film is deposited on the right end face of the metal Bragg grating waveguide.

[0008] The metal Bragg grating waveguide includes a grating waveguide substrate, a back ridge waveguide is disposed on the upper surface of the grating waveguide substrate, a first planar metal Bragg grating is disposed on the left side of the upper surface of the back ridge waveguide, a second planar metal Bragg grating is disposed on the right side of the upper surface of the back ridge waveguide, a phase difference is disposed between the first planar metal Bragg grating and the second planar metal Bragg grating, and a second high-reflection (HR) film is disposed on the top of the first planar metal Bragg grating and the second planar metal Bragg grating.

[0009] A ring resonant waveguide is provided on the front side of the back ridge waveguide.

[0010] The laser output direction of the gain chip is from left to right.

[0011] The second high-reflectivity HR film is specifically prepared by magnetron sputtering on the top of the first planar metal Bragg grating and the second planar metal Bragg grating. The material of the second high-reflectivity HR film is a TiO2 / SiO2 multilayer dielectric composite material, with a thickness of λ / 4 for each layer, a thickness accuracy of ±5nm, a reflectivity R3 > 99.5%, and a surface roughness of less than 0.08nm RMS.

[0012] As a preferred embodiment of the above technical solution, the gain chip adopts an InP / InGaAsP quantum well structure with a central emission wavelength λ ranging from 1530 to 1610 nm and a threshold current of less than 22 mA at 25°C.

[0013] Furthermore, the gain chip adopts an InP / InGaAsP quantum well structure with a center emission wavelength λ of 1550nm and a threshold current of less than 22mA at 25°C.

[0014] As a preferred embodiment of the above technical solution, the thickness of the first antireflective AR film is λ / 4, and the reflectivity R1 < 0.03%; the first high reflectivity HR film is a SiO2 / TiO2 multilayer high reflectivity film, and the reflectivity R2 > 99.9%.

[0015] As a preferred embodiment of the above technical solution, the planar metal Bragg grating waveguide has a length of 1-3 cm, a grating period of 225±0.3 nm, a duty cycle of 50±1%, and a Cr / Au layer thickness of 200±5 nm.

[0016] Furthermore, the planar metal Bragg grating waveguide has a length of 2 cm, a grating period of 225 ± 0.3 nm, and a duty cycle of 50 ± 1%.

[0017] As a preferred embodiment of the above technical solution, the back ridge waveguide has a width of 3-5μm and a height of 2-4μm, and its mode field matching degree with the gain chip is >98%.

[0018] Furthermore, the back ridge waveguide is 4μm wide and 3μm high, with a mode field matching degree of >98% with the gain chip.

[0019] As a preferred embodiment of the above technical solution, the first planar metal Bragg grating and the second planar metal Bragg grating are Cr / Au structures with a thickness of 50nm / 150nm, a reflectivity of >99.9%, and a 3dB reflection bandwidth of <0.1nm.

[0020] As a preferred embodiment of the above technical solution, the phase difference Δφ = π, and the phase control accuracy is < λ / 50 by atomic layer deposition technology.

[0021] This invention provides a laser based on a bimetallic Bragg grating and a top-surface HR reflective film, which has the following advantages:

[0022] 1. Second High-Reflectivity (HR) Film to Prevent Light Energy Loss: A second high-reflectivity (HR) film with a reflectivity greater than 99.5% is disposed on the top of both the first and second planar metallic Bragg gratings. This reflective film operates based on the multilayer thin-film interference effect, efficiently reflecting upwardly diffracted light back into the waveguide. When light propagates in the waveguide and encounters the top Bragg grating, some light diffracts upwards, and the presence of the second high-reflectivity (HR) film effectively reduces this light energy loss. By optimizing the reflection characteristics of the grating, the reflection efficiency of the grating is further enhanced, constraining the light field to propagate within the waveguide and preventing light energy from spilling into free space, thereby maintaining the light-guiding properties of the metallic Bragg grating waveguide and significantly improving the performance of the laser.

[0023] 2. Cost Reduction Advantage: The second high-reflectivity HR film replaces the traditional thick semiconductor secondary epitaxial waveguide layer, fundamentally reducing material costs and process complexity. Simultaneously, this invention employs an electroplating process to fabricate the first and second planar metal Bragg gratings. Compared to traditional semiconductor etching processes, the planar metal gratings, with their flat and regular surfaces, provide high-quality filtering and reflection effects. This process eliminates the need for multiple steps such as etching semiconductor crystal gratings with complex crystal structures, restricted crystal orientation, and high precision and flatness requirements. It avoids reliance on high-precision equipment and special chemical reagents, effectively reducing equipment costs, raw material costs, and process complexity, resulting in significantly lower production costs and demonstrating good economic feasibility.

[0024] 3. Dual-grating synergistic enhancement mechanism: A first planar metallic Bragg grating and a second planar metallic Bragg grating with a phase difference Δφ = π are employed. The reflected light from the two gratings undergoes constructive interference within the cavity, increasing the main peak reflectivity from 95% to 99.9% compared to a traditional single grating. This enhances the intracavity optical field intensity, ensuring high-power, stable laser output. The destructive interference characteristics of the dual gratings are utilized to suppress non-laser modes, according to the formula:

[0025]

[0026] Where R1 and R2 are the reflectivities at both ends of the resonant cavity;

[0027] Theoretically, the side-mode suppression ratio (SMSR) can reach 63dB, effectively weakening the side-mode intensity, improving the purity and stability of the output light, and meeting the requirements of high-precision applications.

[0028] The dual-grating configuration doubles the equivalent cavity length, extending the free spectral range from 50 GHz in traditional external cavities to 100 GHz. This reduces mode competition, improves the wavelength selectivity and stability of the laser, and facilitates the output of different wavelengths of laser light in multi-wavelength applications.

[0029] 4. Linewidth compression technique: Based on the Hakki-Paoli model, the linewidth formula is modified as follows:

[0030]

[0031] Where hν: photon energy; P: laser output power; L: total length of the resonant cavity; L g : Length of the gain medium; R1 and R2 are the reflectivities at both ends of the resonant cavity; α: Linewidth enhancement factor.

[0032] It takes into account the effects of cavity length and gain medium on photon lifetime.

[0033] The loss term in the traditional linewidth formula has been corrected to include the coupling effect of phase noise and carrier fluctuations.

[0034] By employing a first planar metallic Bragg grating with an external cavity length of 3 cm and a reflectivity of 99.92% and a second planar metallic Bragg grating, an ultra-narrow linewidth output of Δν = 0.6 kHz is achieved, while the linewidth of a conventional DFB laser is approximately 1 MHz. Ultra-narrow linewidth lasers have significant application value in fields such as coherent optical communication, high-precision spectral analysis, and quantum key distribution.

[0035] 5. The ring resonant waveguide 3 is a low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide. The low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide is used to provide a narrow-linewidth resonant frequency feedback signal to the linear output laser through optical coupling effect, so that the laser output beamwidth is narrowed and the laser output power is guaranteed. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the front view structure of the gain chip and the metal Bragg grating waveguide in this invention;

[0037] Figure 2 This is a top view of the structure of the present invention.

[0038] Figure 3 This is a front view schematic diagram of the metal Bragg grating waveguide in this invention.

[0039] Figure 4 for Figure 3 The left view.

[0040] In the figure: 1. Gain chip; 11. First high-reflectivity HR film; 12. First anti-reflection AR film; 2. Metal Bragg grating waveguide; 21. Grating waveguide substrate; 22. Back ridge waveguide; 23. First planar metal Bragg grating; 24. Second planar metal Bragg grating; 25. Second anti-reflection AR film; 26. Third anti-reflection AR film; 27. Phase difference; 28. Second high-reflectivity HR film; 3. Ring resonant waveguide. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0042] Example 1

[0043] like Figures 1-4 As shown, in this embodiment, the laser based on a bimetallic Bragg grating and a top surface HR reflective film includes: a gain chip 1, wherein a first high reflectivity HR film 11 is deposited on the left end face of the gain chip 1, and a first antireflection AR film 12 is deposited on the right end face of the gain chip 1.

[0044] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure with a central emission wavelength λ of 1530nm. At 25℃, the threshold current is below 22mA, exhibiting excellent photoelectric conversion performance. The first antireflection AR film 12 has a thickness of λ / 4 and a reflectivity R1 < 0.03% to reduce light reflection loss. The first high-reflectivity HR film 11 is a SiO2 / TiO2 multilayer high-reflectivity film with a reflectivity R2 > 99.9%, enhancing light feedback.

[0045] A metal Bragg grating waveguide 2 is disposed on the right side of the gain chip 1. The right end face of the gain chip 1 is aligned and attached to the left end face of the metal Bragg grating waveguide 2 to form an external cavity structure. A second anti-reflection AR film 25 is deposited on the left end face of the metal Bragg grating waveguide 2, and a third anti-reflection AR film 26 is deposited on the right end face of the metal Bragg grating waveguide 2.

[0046] In a specific implementation, the planar metal Bragg grating waveguide 2 has a length of 1 cm, a grating period of 225±0.3 nm, a duty cycle of 50±1%, and a Cr / Au layer thickness of 200±5 nm (50 nm Cr / 150 nm Au), forming a grating structure with high reflectivity.

[0047] The metal Bragg grating waveguide 2 includes a grating waveguide substrate 21. A back ridge waveguide 22 is disposed on the upper surface of the grating waveguide substrate 21. A first planar metal Bragg grating 23 is disposed on the left side of the upper surface of the back ridge waveguide 22, and a second planar metal Bragg grating 24 is disposed on the right side of the upper surface of the back ridge waveguide 22. A phase difference 27 is disposed between the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24. A second high-reflection HR film 28 is disposed on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24.

[0048] A ring resonant waveguide 3 is provided on the front side of the back ridge waveguide 22;

[0049] The laser output direction of the gain chip 1 is from left to right.

[0050] The ring resonant waveguide 3 is a low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide. The low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide is used to provide a narrow-linewidth resonant frequency feedback signal to the linear output laser through optical coupling effect, so that the laser output beamwidth is narrowed and the laser output power is guaranteed.

[0051] The second high-reflectivity HR film 28 is specifically fabricated as follows: it is deposited on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 by magnetron sputtering. The material of the second high-reflectivity HR film 28 is a TiO2 / SiO2 multilayer dielectric composite material, with a thickness of λ / 4 for each layer, a thickness accuracy of ±5nm, a reflectivity R3 > 99.5%, and a surface roughness of less than 0.08nm RMS, so as to achieve high reflectivity and good optical performance.

[0052] Furthermore, the phase difference 27Δφ=π is controlled with a phase control accuracy of <λ / 50 through atomic layer deposition technology.

[0053] In specific implementation, the back ridge waveguide 22 is 3μm wide and 2μm high, and its mode field matching degree with the gain chip 1 is >98%.

[0054] In specific implementation, the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 are Cr / Au structures with a thickness of 50nm / 150nm, a reflectivity of >99.9%, and a 3dB reflection bandwidth of <0.1nm.

[0055] It should be noted that the laser based on a bimetallic Bragg grating and a top-surface HR reflective film has a total external cavity length L. cavity =800μm+L wg Free spectral range FSR > 100 GHz.

[0056] Example 2

[0057] like Figures 1-4 As shown, in this embodiment, the laser based on a bimetallic Bragg grating and a top surface HR reflective film includes: a gain chip 1, wherein a first high reflectivity HR film 11 is deposited on the left end face of the gain chip 1, and a first antireflection AR film 12 is deposited on the right end face of the gain chip 1.

[0058] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure with a central emission wavelength λ of 1610nm. At 25℃, the threshold current is below 22mA, exhibiting excellent photoelectric conversion performance. The first antireflection AR film 12 has a thickness of λ / 4 and a reflectivity R1 < 0.03% to reduce light reflection loss. The first high-reflectivity HR film 11 is a SiO2 / TiO2 multilayer high-reflectivity film with a reflectivity R2 > 99.9%, enhancing light feedback.

[0059] A metal Bragg grating waveguide 2 is disposed on the right side of the gain chip 1. The right end face of the gain chip 1 is aligned and attached to the left end face of the metal Bragg grating waveguide 2 to form an external cavity structure. A second anti-reflection AR film 25 is deposited on the left end face of the metal Bragg grating waveguide 2, and a third anti-reflection AR film 26 is deposited on the right end face of the metal Bragg grating waveguide 2.

[0060] In a specific implementation, the planar metal Bragg grating waveguide 2 has a length of 3cm, a grating period of 225±0.3nm, a duty cycle of 50±1%, and a Cr / Au layer thickness of 200±5nm (50nmCr / 150nmAu), forming a grating structure with high reflectivity.

[0061] The metal Bragg grating waveguide 2 includes a grating waveguide substrate 21. A back ridge waveguide 22 is disposed on the upper surface of the grating waveguide substrate 21. A first planar metal Bragg grating 23 is disposed on the left side of the upper surface of the back ridge waveguide 22, and a second planar metal Bragg grating 24 is disposed on the right side of the upper surface of the back ridge waveguide 22. A phase difference 27 is disposed between the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24. A second high-reflection HR film 28 is disposed on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24.

[0062] A ring resonant waveguide 3 is provided on the front side of the back ridge waveguide 22;

[0063] The laser output direction of the gain chip 1 is from left to right.

[0064] The ring resonant waveguide 3 is a low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide. The low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide is used to provide a narrow-linewidth resonant frequency feedback signal to the linear output laser through optical coupling effect, so that the laser output beamwidth is narrowed and the laser output power is guaranteed.

[0065] The second high-reflectivity HR film 28 is specifically fabricated as follows: it is deposited on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 by magnetron sputtering. The material of the second high-reflectivity HR film 28 is a TiO2 / SiO2 multilayer dielectric composite material, with a thickness of λ / 4 for each layer, a thickness accuracy of ±5nm, a reflectivity R3 > 99.5%, and a surface roughness of less than 0.08nm RMS, so as to achieve high reflectivity and good optical performance.

[0066] Furthermore, the phase difference 27Δφ=π is controlled with a phase control accuracy of <λ / 50 through atomic layer deposition technology.

[0067] In specific implementation, the back ridge waveguide 22 is 5μm wide and 4μm high, and its mode field matching degree with the gain chip 1 is >98%.

[0068] In specific implementation, the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 are Cr / Au structures with a thickness of 50nm / 150nm, a reflectivity of >99.9%, and a 3dB reflection bandwidth of <0.1nm.

[0069] It should be noted that the laser based on a bimetallic Bragg grating and a top-surface HR reflective film has a total external cavity length L. cavity =800μm+L wg Free spectral range FSR > 100 GHz.

[0070] Example 3

[0071] like Figures 1-4 As shown, in this embodiment, the laser based on a bimetallic Bragg grating and a top surface HR reflective film includes: a gain chip 1, wherein a first high reflectivity HR film 11 is deposited on the left end face of the gain chip 1, and a first antireflection AR film 12 is deposited on the right end face of the gain chip 1.

[0072] In specific implementation, the gain chip 1 adopts an InP / InGaAsP quantum well structure with a central emission wavelength λ of 1550nm. At 25℃, the threshold current is below 22mA, exhibiting excellent photoelectric conversion performance. The first antireflection AR film 12 has a thickness of λ / 4 and a reflectivity R1 < 0.03% to reduce light reflection loss. The first high-reflectivity HR film 11 is a SiO2 / TiO2 multilayer high-reflectivity film with a reflectivity R2 > 99.9%, enhancing light feedback.

[0073] A metal Bragg grating waveguide 2 is disposed on the right side of the gain chip 1. The right end face of the gain chip 1 is aligned and attached to the left end face of the metal Bragg grating waveguide 2 to form an external cavity structure. A second anti-reflection AR film 25 is deposited on the left end face of the metal Bragg grating waveguide 2, and a third anti-reflection AR film 26 is deposited on the right end face of the metal Bragg grating waveguide 2.

[0074] In a specific implementation, the planar metal Bragg grating waveguide 2 has a length of 2cm, a grating period of 225±0.3nm, a duty cycle of 50±1%, and a Cr / Au layer thickness of 200±5nm (50nmCr / 150nmAu), forming a grating structure with high reflectivity.

[0075] The metal Bragg grating waveguide 2 includes a grating waveguide substrate 21. A back ridge waveguide 22 is disposed on the upper surface of the grating waveguide substrate 21. A first planar metal Bragg grating 23 is disposed on the left side of the upper surface of the back ridge waveguide 22, and a second planar metal Bragg grating 24 is disposed on the right side of the upper surface of the back ridge waveguide 22. A phase difference 27 is disposed between the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24. A second high-reflection HR film 28 is disposed on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24.

[0076] A ring resonant waveguide 3 is provided on the front side of the back ridge waveguide 22;

[0077] The laser output direction of the gain chip 1 is from left to right.

[0078] The ring resonant waveguide 3 is a low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide. The low-energy-loss silicon-based compound long-cavity narrow-linewidth ring resonant waveguide is used to provide a narrow-linewidth resonant frequency feedback signal to the linear output laser through optical coupling effect, so that the laser output beamwidth is narrowed and the laser output power is guaranteed.

[0079] The second high-reflectivity HR film 28 is specifically fabricated as follows: it is deposited on the top of the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 by magnetron sputtering. The material of the second high-reflectivity HR film 28 is a TiO2 / SiO2 multilayer dielectric composite material, with a thickness of λ / 4 for each layer, a thickness accuracy of ±5nm, a reflectivity R3 > 99.5%, and a surface roughness of less than 0.08nm RMS, so as to achieve high reflectivity and good optical performance.

[0080] Furthermore, the phase difference 27Δφ=π is controlled with a phase control accuracy of <λ / 50 through atomic layer deposition technology.

[0081] In specific implementation, the back ridge waveguide 22 is 4μm wide and 3μm high, and its mode field matching degree with the gain chip 1 is >98%.

[0082] In specific implementation, the first planar metal Bragg grating 23 and the second planar metal Bragg grating 24 are Cr / Au structures with a thickness of 50nm / 150nm, a reflectivity of >99.9%, and a 3dB reflection bandwidth of <0.1nm.

[0083] It should be noted that the laser based on a bimetallic Bragg grating and a top-surface HR reflective film has a total external cavity length L. cavity =800μm+L wg Free spectral range FSR > 100 GHz.

[0084] Performance testing was conducted on the three lasers provided in Examples 1, 2, and 3. The test results showed that the linewidth was 0.6 kHz, the SMSR was 63 dB, and the threshold current was 22 mA, verifying the effectiveness of the present invention.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A laser based on a bimetallic Bragg grating and a top-surface HR reflective film, comprising a gain chip (1), characterized in that: The gain chip (1) has a first high reflectance HR film (11) deposited on its left end face and a first antireflection AR film (12) deposited on its right end face. A metal Bragg grating waveguide (2) is provided on the right side of the gain chip (1). The right end face of the gain chip (1) is aligned and attached to the left end face of the metal Bragg grating waveguide (2) to form an external cavity structure. A second anti-reflection AR film (25) is deposited on the left end face of the metal Bragg grating waveguide (2), and a third anti-reflection AR film (26) is deposited on the right end face of the metal Bragg grating waveguide (2). The metal Bragg grating waveguide (2) includes a grating waveguide substrate (21), a back ridge waveguide (22) is provided on the upper surface of the grating waveguide substrate (21), a first planar metal Bragg grating (23) is provided on the left side of the upper surface of the back ridge waveguide (22), a second planar metal Bragg grating (24) is provided on the right side of the upper surface of the back ridge waveguide (22), a phase difference (27) is provided between the first planar metal Bragg grating (23) and the second planar metal Bragg grating (24), and a second high-reflection HR film (28) is provided on the top of the first planar metal Bragg grating (23) and the second planar metal Bragg grating (24); A ring resonant waveguide (3) is provided on the front side of the back ridge waveguide (22); The laser output direction of the gain chip (1) is from left to right.

2. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 1, characterized in that: The gain chip (1) adopts an InP / InGaAsP quantum well structure with a central emission wavelength λ of 1550nm and a threshold current of less than 22mA at 25℃.

3. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 2, characterized in that, The second high-reflectivity HR film (28) is specifically prepared by magnetron sputtering on the top of the first planar metal Bragg grating (23) and the second planar metal Bragg grating (24). The material of the second high-reflectivity HR film (28) is a TiO2 / SiO2 multilayer dielectric composite material with a thickness of λ / 4 per layer, a thickness accuracy of ±5nm, a reflectivity R3 > 99.5%, and a surface roughness of less than 0.08nm RMS.

4. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 2, characterized in that: The first antireflective AR film (12) has a thickness of λ / 4 and a reflectivity R1 < 0.03%; the first high reflectivity HR film (11) is a SiO2 / TiO2 multilayer high reflectivity film with a reflectivity R2 > 99.9%.

5. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 1, characterized in that: The planar metal Bragg grating waveguide (2) has a length of 2 cm, a grating period of 225 ± 0.3 nm, and a duty cycle of 50 ± 1%.

6. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 1, characterized in that: The back ridge waveguide (22) is 4μm wide and 3μm high, and its mode field matching degree with the gain chip (1) is >98%.

7. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 1, characterized in that: The first planar metal Bragg grating (23) and the second planar metal Bragg grating (24) are Cr / Au structures with a thickness of 50nm / 150nm, a reflectivity of >99.9%, and a 3dB reflection bandwidth of <0.1nm.

8. The laser based on a bimetallic Bragg grating and a top-surface HR reflective film according to claim 2, characterized in that: The phase difference (27) Δφ = π is controlled by atomic layer deposition technology to achieve a phase control accuracy of <λ / 50.

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