CN114256722B - On-Chip Integrated Narrow Linewidth Laser - Google Patents

Abstract

The invention provides an on-chip integrated narrow linewidth laser, wherein a uniform grating and a first reflective semiconductor optical amplifier form a first sub-resonant cavity, the uniform grating and a second reflective semiconductor optical amplifier, a first micro-ring resonator, a second micro-ring resonator, a phase shifter and an optical coupler form a second sub-resonant cavity, the first sub-resonant cavity and the second sub-resonant cavity are coupled through the uniform grating to form a coupled resonant cavity, current is injected into the first reflective semiconductor optical amplifier and the second reflective semiconductor optical amplifier at the same time, and optical signals generated by spontaneous radiation of the two reflective semiconductor optical amplifiers enhance the mode selection effect of a system in the coupled resonant cavity by means of the reflection characteristic of the uniform grating and vernier effect of the first micro-ring resonator and the second micro-ring resonator. In addition, the mode selection capability is further enhanced by using the difference of the cavity length of the first sub-resonant cavity and the cavity length of the second sub-resonant cavity, so that single-mode laser output is realized.

Description

On-Chip Integrated Narrow Linewidth Laser

technical field

The invention relates to the technical field of microwave photonics, in particular to an on-chip integrated narrow linewidth laser.

Background technique

Narrow linewidth lasers have important applications in high-resolution spectroscopy, optical atomic clocks, and low-noise microwave sources due to their high monochromaticity, high spectral purity, and low phase noise.

Traditional narrow-linewidth lasers mainly use the resonant system composed of fiber Bragg grating and semiconductor optical amplifier, so that only the resonant frequency in the reflection spectrum can get enough optical gain, so as to achieve single-mode output, but this method is because of the existence of optical fiber, so It is sensitive to the influence of external temperature and vibration, and the current line width can only reach the order of kHz.

Existing on-chip narrow-linewidth lasers mainly use the vernier effect of double or triple microrings to select the wide-spectrum light of the semiconductor optical amplifier, and through the filtering effect of the high-quality factor microring and its unique optical delay effect, Single-mode laser output on the order of hundreds of Hz can be achieved. However, due to the attenuation effect of multiple microrings on the optical power and the large coupling loss between chips, the output power of the on-chip narrow linewidth laser has higher requirements on the regulation of the working state of the microrings and the coupling process.

Contents of the invention

(1) Technical problems to be solved

In view of the above shortcomings of the prior art, the main purpose of the present invention is to provide an on-chip integrated narrow linewidth laser, in order to at least partly solve at least one of the above technical problems.

(2) Technical solution

In order to achieve the above object, according to one aspect of the present invention, an on-chip integrated narrow linewidth laser is proposed, including:

Coupled resonator and Mach-Zehnder interference structure 300;

The coupling resonator includes a first sub-resonator 100 and a second sub-resonator 200, and the first sub-resonator 100 and the second sub-resonator 200 are coupled through a uniform grating 2;

The first sub-resonator 100 is connected to the second sub-resonator 200, and the second sub-resonator 200 is connected to the Mach-Zehnder interference structure 300;

The first sub-resonator 100 is configured to select and amplify optical signals that meet the propagation conditions of the first sub-resonator 100;

The second sub-resonator 200 is configured to select and amplify optical signals that meet the propagation conditions of the second sub-resonator 200;

The coupling resonator is used to select an optical signal that simultaneously satisfies the propagation conditions of the first sub-resonator 100 and the second sub-resonator 200;

The Mach-Zehnder interference structure 300 is configured to output the optical signal selected by the coupling resonator and satisfy the propagation conditions of the first sub-resonator 100 and the second sub-resonator 200 at the same time.

In a further embodiment, the first sub-resonator 100 includes: a first reflective semiconductor optical amplifier 1 and the uniform grating 2, and the first reflective semiconductor optical amplifier 1 and the uniform grating 2 are the The two ends of the first sub-resonator 100, the first reflective semiconductor optical amplifier 1 is connected to the uniform grating 2;

The first reflective semiconductor optical amplifier 1 is used to generate spontaneous emission under the action of the driving current, and the optical signal part generated by the spontaneous emission of the first reflective semiconductor optical amplifier 1 is in the first sub-resonator cavity 100 propagating back and forth, partly transmitted to the second sub-resonator 200 through the uniform grating 2;

The uniform grating 2 is used to select the optical signals reaching the uniform grating 2, partially reflect or completely reflect the optical signals within a specific wavelength range, and completely transmit the optical signals outside the specific wavelength range.

In a further embodiment, the second sub-resonator 200 includes: the uniform grating 2, a phase shifter 3, a first microring resonator 201, a second microring resonator 202, an optical coupler 18 and a second Two reflective semiconductor optical amplifiers 21, the second reflective semiconductor optical amplifier 21 and the uniform grating 2 are two ends of the second sub-resonator 200; the uniform grating 2 is connected to the phase shifter 3 , the phase shifter 3 is connected to the first microring resonator 201, the first microring resonator 201 is connected to the second microring resonator 202, and the second microring resonator 202 and The optical coupler 18 is connected, and the optical coupler 18 is connected to the second reflective semiconductor optical amplifier 21;

The second reflective semiconductor optical amplifier 21 is configured to generate spontaneous emission under the action of a driving current, and part of the optical signal generated by the spontaneous emission of the second reflective semiconductor optical amplifier 21 is in the second sub-resonator cavity 200 propagating back and forth, partly transmitted to the first sub-resonator 100 through the uniform grating 2;

The phase shifter 3 is used to adjust the phase of the optical signal reaching the phase shifter 3, so that the resonant wavelength of the second sub-resonator 200 is the same as that of the first microring resonator 201 and the second The resonant wavelengths of the microring resonators 202 overlap to increase the power of the optical signal reaching the phase shifter 3 .

In a further embodiment, one end of the first reflective semiconductor optical amplifier 1 and the second reflective semiconductor optical amplifier 21 is coated with a film with a reflectivity higher than 90% for optical signals.

In a further embodiment, the first microring resonator 201 includes: an optical coupler 4, a phase shifter 5, an optical coupler 6, a phase shifter 7, an optical coupler 8, a phase shifter 9, an optical coupler 10, the connection mode is: the optocoupler 4 is connected to the phase shifter 5, the phase shifter 5 is connected to the optocoupler 6, the optocoupler 6 is connected to the phase shifter 7, the phase shifter 7 is connected to the optocoupler 8, and the optocoupler 8 is connected to the phase shifter 9, and the phase shifter 9 is connected to the optocoupler 10;

The optocoupler 4 is connected to the optocoupler 6, the optocoupler 8 is connected to the optocoupler 10, and the optocoupler 4 is connected to the optocoupler 10;

The second microring resonator 202 includes: an optical coupler 11, a phase shifter 12, an optical coupler 13, an optical coupler 14, a phase shifter 15, an optical coupler 16, and a phase shifter 17, and the connection method is: The optocoupler 11 is connected to the phase shifter 12, the phase shifter 12 is connected to the optocoupler 13, the optocoupler 13 is connected to the optocoupler 14, the optocoupler 14 is connected to the phase shifter 15, and the phase shifter 15 is connected to the optocoupler 16, Optical coupler 16 is connected to phase shifter 17;

The optocoupler 11 is connected to the optocoupler 13, the optocoupler 14 is connected to the optocoupler 16, and the optocoupler 11 is connected to the phase shifter 17;

The optical coupler 4 is connected to the phase shifter 3 , the optical coupler 10 is connected to the optical coupler 11 , and the optical coupler 16 is connected to the optical coupler 18 .

In a further embodiment, the first microring resonator 201 and the second microring resonator 202 have different radii and free spectral ranges, forming a microring resonator of an up-down channel type, when the second When the optical signal propagating in the sub-resonator 200 passes through the first microring resonator 201 and the second microring resonator 202, a vernier effect occurs, and only the optical signal satisfying the filtering condition of the vernier effect can continue to propagate.

In a further embodiment, the free spectral range of the first microring resonator 201, the free spectral range of the second microring resonator 202, the first microring resonator 201 and the second microring resonator The total free spectral range of the ring resonator 202 is related as follows:

Wherein, FSR ₁ is the free spectral range of the first microring resonator 201, FSR ₂ is the free spectral range of the second microring resonator 202, and FSR is the free spectral range of the first microring resonator 201 and the The total free spectral range of the second microring resonator 202 .

In a further embodiment, driving current needs to be injected into the first reflective semiconductor optical amplifier 1 and the second reflective semiconductor optical amplifier 21 at the same time.

In a further embodiment, the Mach-Zehnder interference structure 300 includes the optical coupler 18, the phase shifter 20 and the Y branch 19, the optical coupler 18 is connected to the phase shifter 20, and the optical coupler 18 is connected to the Y branch 19, the phase shifter 20 is connected to the Y branch 19, the optical signal selected by the coupling resonator is output through the Y branch 19, and the Mach-Zehnder is changed by adjusting the current injected into the phase shifter 20 The phase of the signal arm or the reference arm of the interference structure 300 makes the optical signals of the signal arm and the reference arm interfere constructively when reaching the Y branch 19 , increasing the power of the output optical signal.

In a further embodiment, the propagation condition of the first sub-resonator 100 is: simultaneously satisfy the preset resonance condition of the first sub-resonator 100 and the preset reflection condition of the uniform grating 2;

The propagation condition of the second sub-resonator 200 is: simultaneously satisfy the preset resonance condition of the second sub-resonator 200, the preset reflection condition of the uniform grating 2, the first microring resonator 201 and the second Microring resonator 202 vernier effect filter conditions.

(3) Beneficial effects

Based on the above technical solution, it can be seen that the on-chip integrated narrow linewidth laser of the present invention has the following beneficial results:

(1) The present invention greatly reduces the volume of narrow-linewidth lasers by utilizing various devices integrated on a chip, and reduces the impact of vibration on traditional optical fiber narrow-linewidth lasers;

(2) The present invention combines the coupling resonator, the double-up and down-channel type micro-ring resonator structure and the uniform grating, which greatly enhances the mode selection ability of the laser;

(3) the present invention adopts the microring resonator structure of double up-down channel type to increase the effective cavity length of the second sub-resonator cavity in the link, thereby reducing the influence of reflective semiconductor optical amplifier 21 spontaneous radiation on the line width, It can make the output laser linewidth of the present invention reach the order of 10Hz;

(4) The present invention makes the microring structure work in the critical coupling state by adjusting the current injected into the part of the phase shifter in the double up and down channel type microring resonator structure, so that the optical signal power after coupling out the two microring resonators Reaching the maximum, the attenuation influence of the first microring resonator and the second microring resonator on the power of the optical signal is reduced.

Description of drawings

FIG. 1 is a schematic structural view of an on-chip integrated narrow linewidth laser according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of the reflection spectrum simulation of a uniform grating;

Fig. 3 is a schematic diagram of the connection relationship between the first microring resonator 201 and the second microring resonator 202 in Fig. 1;

FIG. 4 is a schematic diagram of the spectrum response based on the vernier effect when the optical signal enters the first microring resonator 201 and the second microring resonator 202 in FIG. 1;

FIG. 5 is a schematic diagram of the specific connection of the on-chip narrow linewidth laser according to the embodiment of the present invention.

Explanation of reference signs:

1-First reflective semiconductor optical amplifier 2-Uniform grating 3-Phase shifter

4-Optocoupler 5-Phase Shifter 6-Optocoupler

7-Phase shifter 8-Optocoupler 9-Phase shifter

10-Optocoupler 11-Optocoupler 12-Phase Shifter

13-Optocoupler 14-Optocoupler 15-Phase Shifter

16-Optocoupler 17-Phase Shifter 18-Optocoupler

19-Y branch 20-phase shifter 21-second reflective semiconductor optical amplifier

100-First sub-resonator 200-Second sub-resonator 300-Mach-Zehnder interference structure

201 - first microring resonator 202 - second microring resonator

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.

The present invention is based on the integrated microwave photon technology, and injects current into the first reflective semiconductor optical amplifier 1 and the second reflective semiconductor optical amplifier 21 at the same time, and the optical signal generated by the spontaneous radiation of the first reflective semiconductor optical amplifier 1 The optical signal generated by the spontaneous emission of the second reflective semiconductor optical amplifier 21 propagates back and forth in the resonant cavity 100 , and propagates back and forth in the second sub-resonant cavity 200 . The optical signal generated by the spontaneous emission of the first reflective semiconductor optical amplifier 1 in the first sub-resonator 100 is selected by the resonance condition of the first sub-resonator 100 and the reflection condition of the uniform grating 2, and the optical signal satisfying these two conditions is in the Large gain is obtained in the first sub-resonator 100, and the optical signal generated by the spontaneous radiation of the second reflective semiconductor optical amplifier 21 in the second sub-resonator 200 is subjected to the resonance condition of the second sub-resonator 200 and the reflection condition of the uniform grating 2 1. The selection of the filtering conditions of the double microring vernier effect, the optical signal satisfying these three conditions obtains a relatively large gain in the second sub-resonator 200 . In addition, since the first sub-resonator 100 and the second sub-resonator 200 are coupled through the uniform grating 2 to form a coupled resonator and affect each other, the optical signal that simultaneously satisfies the resonance conditions of the first sub-resonator and the second sub-resonator will be obtained Maximum gain. When the driving current increases to the threshold value, the ideal single-mode laser is finally obtained through the mode competition in the coupling resonator, and the single-mode laser is output through the Mach-Zehnder interference structure 300 .

The technical solutions of the present invention will be described in detail below through specific embodiments in conjunction with the accompanying drawings.

Fig. 1 is a structural schematic diagram of an on-chip integrated narrow linewidth laser according to an embodiment of the present invention. As shown in Fig. 1, the embodiment of the present invention mainly includes: a first reflective semiconductor optical amplifier 1, a uniform grating 2, a phase shifter 3, a first A microring resonator 201 , a second microring resonator 202 , an optical coupler 18 , a Y branch 19 , a phase shifter 20 , and a second reflective semiconductor optical amplifier 21 .

The first sub-resonator 100 includes: a first reflective semiconductor optical amplifier 1 and a uniform grating 2 .

The second sub-resonator 200 includes: a uniform grating 2 , a phase shifter 3 , a first microring resonator 201 , a second microring resonator 202 , an optical coupler 18 , and a second reflective semiconductor optical amplifier 21 .

The Mach-Zehnder interference structure 300 includes: an optical coupler 18 , a Y branch 19 , and a phase shifter 20 .

FIG. 2 is a schematic diagram of a simulation of the reflection spectrum of a uniform grating. As shown in FIG. 2 , the uniform grating 2 is used to partially reflect or completely reflect optical signals within a specific wavelength range, and completely transmit optical signals outside the specific wavelength range.

Among them, the first sub-resonator 100 is used to select the optical signal that simultaneously satisfies the preset resonance condition of the first sub-resonator 100 and the preset reflection condition of the uniform grating 2; the second sub-resonator 200 is used to select an optical signal that simultaneously satisfies the second Optical signals of the preset resonance conditions of the sub-resonator 200 , the preset reflection conditions of the uniform grating 2 , and the Vernier effect filtering conditions of the first microring resonator 201 and the second microring resonator 202 .

In the embodiment of the present invention, current is injected into the first reflective semiconductor optical amplifier 1 and the second reflective semiconductor optical amplifier 21 at the same time.

In the first sub-resonator cavity 100, the first reflective semiconductor optical amplifier 1 generates spontaneous emission under the action of the driving current, and the optical signal generated by the spontaneous emission enters the uniform grating 2, because the uniform grating 2 is sensitive to the optical signal of a specific wavelength range It has the function of reflection, and part of the optical signal satisfying the reflection condition of the uniform grating 2 is returned according to the original optical path, and the other part is transmitted through the uniform grating 2. Since the first reflective semiconductor optical amplifier 1 is coated with a reflectance of more than 90% on the optical signal at one end Therefore, the optical signal reflected back from the uniform grating 2 is amplified by the first reflective semiconductor optical amplifier 1 and then reflected again, so the first reflective semiconductor optical amplifier 1 and the uniform grating 2 are two parts of the first sub-resonator 100 At the end, the optical signal is continuously reflected in the first sub-resonator 100, and the cavity length of the first sub-resonator 100 and the uniform grating 2 have the function of mode selection.

At the same time, in the second sub-resonator 200, the second reflective semiconductor optical amplifier 21 generates spontaneous emission under the action of the driving current, and the optical signal generated by the spontaneous emission passes through the optical coupler 18, and part of the optical signal is coupled into the Mach-Zehnder After the interference structure 300 exits, another part of the optical signal is coupled into the second microring resonator 202 and then transmitted to the first microring resonator 201. Since the radii of the two microring resonators are different, a vernier effect occurs. After the second microring resonator The selection of the second microring resonator 202 and the first microring resonator 201, part of the optical signal is coupled out from the first microring resonator 201, and the optical signal transmitted by the first microring resonator 201 arrives through the phase shifter 3 Uniform grating 2, part of the optical signal satisfying the reflection condition of uniform grating 2 is returned according to the original optical path, and the other part is transmitted through uniform grating 2, because the second reflective semiconductor optical amplifier 21 is coated with an optical signal with a reflectivity higher than 90% at one end Therefore, the optical signal reflected back from the uniform grating 2 is amplified by the second reflective semiconductor optical amplifier 21 and then reflected again, so the second reflective semiconductor optical amplifier 21 and the uniform grating 2 are the two ends of the second sub-resonator 200 , the optical signal is continuously reflected in the second sub-resonator 200, the cavity length of the second sub-resonator 200, the first microring resonator 201, the second microring resonator 202 and the uniform grating 2 have the function of mode selection.

Wherein, the phase shifter 3 in the second resonant cavity 200 is used to adjust the phase of the optical signal, so that the resonant wavelength of the second sub-resonant cavity 200 coincides with the resonant wavelength of the two microring resonators, increasing the size of the second sub-resonant cavity 200 The power of the selected optical signal.

Fig. 3 is a schematic diagram of the connection relation between the first microring resonator 201 and the second microring resonator 202 in Fig. 1, as shown in Fig. 3, the first microring resonator 201 comprises: optical coupler 4, phase shifter 5. Optical coupler 6, phase shifter 7, optical coupler 8, phase shifter 9, optical coupler 10.

The second microring resonator 202 includes: an optical coupler 11 , a phase shifter 12 , an optical coupler 13 , an optical coupler 14 , a phase shifter 15 , an optical coupler 16 , and a phase shifter 17 .

In the embodiment of the present invention, in order to make the first microring resonator 201 and the second microring resonator 202 have higher side-mode suppression ratio and higher filtered optical power, the injection into the phase shifter 15, the The currents in the phase shifter 12, the phase shifter 9 and the phase shifter 5 change the coupling state of the first microring resonator 201 and the second microring resonator 202 so that the two microring resonators reach a critical coupling state.

FIG. 4 is a schematic diagram of the spectrum response based on the vernier effect when the optical signal enters the first microring resonator 201 and the second microring resonator 202 in FIG. 1. As shown in FIG. 4, the first microring resonator 201 and the second microring resonator The two microring resonators 202 have different radii and free spectral ranges. When the optical signal passes through the two microring resonators, a vernier effect will appear. The first microring resonator and the second microring resonator are equivalent to a filter Only optical signals that meet the filtering conditions of the filter can continue to propagate.

Wherein, the spectral range of the filters equivalent to the first microring resonator 201 and the second microring resonator 202 is the total free spectral range of the first microring resonator 201 and the second microring resonator 202 . The free spectral range of the first microring resonator 201, the free spectral range of the second microring resonator 202, the total free spectral range of the first microring resonator 201 and the second microring resonator 202 are as follows:

Wherein, FSR ₁ is the free spectral range of the first microring resonator 201, FSR ₂ is the free spectral range of the second microring resonator 202, FSR is the total of the first microring resonator 201 and the second microring resonator 202 free spectral range.

Fig. 5 is a specific connection schematic diagram of an on-chip narrow linewidth laser according to an embodiment of the present invention. As shown in Fig. 5, the present invention specifically includes: a first reflective semiconductor optical amplifier 1, a uniform grating 2, a phase shifter 3, and an optical coupler 4. Phase shifter 5, optocoupler 6, phase shifter 7, optocoupler 8, phase shifter 9, optocoupler 10, optocoupler 11, phase shifter 12, optocoupler 13, optocoupler 14 , a phase shifter 15 , an optical coupler 16 , a phase shifter 17 , an optical coupler 18 , a Y branch 19 , a phase shifter 20 , and a second reflective semiconductor optical amplifier 21 .

Wherein, the uniform grating 2 is used as the common end face of the first sub-resonator 100 and the second sub-resonator 200, and the optical signal reaching the uniform grating 2 is partially reflected back to the original optical path, and a part of the optical signal is mutually coupled between the resonators, If the optical signal that satisfies the resonance condition of one sub-resonator is transmitted into another sub-resonator and satisfies the resonance condition of another sub-resonator at the same time, interference and cancellation will not occur after reflection, ensuring that the maximum power is transmitted back to the atomic resonator , to obtain a higher total gain; on the contrary, if the optical signal that satisfies the resonance condition of one sub-resonator is transmitted into another sub-resonator, but does not meet the resonance condition of the other sub-resonator, interference and destructive cancellation will occur through reflection, so that The optical signal gets an overall gain reduction. Finally, the driving current of the first reflective semiconductor optical amplifier 1 and the second reflective semiconductor optical amplifier 21 is appropriately increased. When the total gain of the system is equal to the total loss, the mode competition makes a certain light that satisfies the resonance conditions of the two sub-resonators simultaneously The signal obtains maximum gain while suppressing other optical signals to realize single-mode laser output through the Mach-Zehnder interference structure 300 .

Wherein, the phase of the signal arm or the reference arm of the Mach-Zehnder interference structure 300 is changed by adjusting the current injected into the phase shifter 20, so that the optical signals of the signal arm and the reference arm interfere constructively when reaching the Y branch 19, Increase the power of the output optical signal.

In addition, the above-mentioned definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily and well-known replace their structures, for example: each The phase shifter at the place is replaced by a phase modulator; the on-chip reflective semiconductor optical amplifier can be replaced by an erbium-doped fiber amplifier. Also, the attached drawings are simplified and used for illustration purposes. The number, shape and size of the devices shown in the drawings can be modified according to the actual situation, and the configuration of the devices may be more complicated.

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. An on-chip integrated narrow linewidth laser comprising:

coupling the resonant cavity and the mach-zehnder interference structure (300);

the coupled resonator comprises a first sub-resonator (100) and a second sub-resonator (200), the second sub-resonator (200) comprising: a uniform grating (2), a phase shifter (3), a first micro-ring resonator (201), a second micro-ring resonator (202), an optical coupler (18) and a second reflective semiconductor optical amplifier (21), wherein the second reflective semiconductor optical amplifier (21) and the uniform grating (2) are two ends of the second sub-resonant cavity (200); the uniform grating (2) is connected with the phase shifter (3), the phase shifter (3) is connected with the first micro-ring resonator (201), the first micro-ring resonator (201) is connected with the second micro-ring resonator (202), the second micro-ring resonator (202) is connected with the optical coupler (18), and the optical coupler (18) is connected with the second reflective semiconductor optical amplifier (21);

the second reflective semiconductor optical amplifier (21) is used for generating spontaneous radiation under the action of a driving current, and an optical signal generated by the spontaneous radiation of the second reflective semiconductor optical amplifier (21) partially propagates back and forth in the second sub-resonant cavity (200) and partially is transmitted to the first sub-resonant cavity (100) through the uniform grating (2);

the phase shifter (3) is used for adjusting the phase of the optical signal reaching the phase shifter (3), so that the resonance wavelength of the second sub-resonant cavity (200) coincides with the resonance wavelengths of the first micro-ring resonator (201) and the second micro-ring resonator (202), and the power of the optical signal reaching the phase shifter (3) is increased;

the first sub-resonant cavity (100) and the second sub-resonant cavity (200) are coupled by a uniform grating (2);

the first sub-resonant cavity (100) is connected with the second sub-resonant cavity (200), and the second sub-resonant cavity (200) is connected with the Mach-Zehnder interference structure (300);

the first sub-resonant cavity (100) is used for selecting an optical signal meeting the propagation condition of the first sub-resonant cavity (100) to amplify;

the second sub-resonant cavity (200) is used for selecting and amplifying the optical signals meeting the propagation conditions of the second sub-resonant cavity (200);

the coupled resonator is configured to select an optical signal that satisfies propagation conditions of the first sub-resonator (100) and the second sub-resonator (200) simultaneously;

the Mach-Zehnder interference structure (300) is configured to output an optical signal that satisfies propagation conditions of the first sub-resonator (100) and the second sub-resonator (200) while the coupled resonator is selected.

2. The integrated narrow linewidth laser on chip of claim 1 wherein the first sub-cavity (100) comprises: the first reflective semiconductor optical amplifier (1) and the uniform grating (2), wherein the first reflective semiconductor optical amplifier (1) and the uniform grating (2) are arranged at two ends of the first sub-resonant cavity (100), and the first reflective semiconductor optical amplifier (1) is connected with the uniform grating (2);

the first reflective semiconductor optical amplifier (1) is used for generating spontaneous radiation under the action of a driving current, and an optical signal generated by the spontaneous radiation of the first reflective semiconductor optical amplifier (1) is partially transmitted back and forth in the first sub-resonant cavity (100) and partially transmitted to the second sub-resonant cavity (200) through the uniform grating (2);

the uniform grating (2) is used for selecting the optical signals reaching the uniform grating (2), partially reflecting or completely reflecting the optical signals within a specific wavelength range and completely transmitting the optical signals outside the specific wavelength range.

3. The on-chip integrated narrow linewidth laser according to claim 2, characterized in that one end of the first reflective semiconductor optical amplifier (1) and the second reflective semiconductor optical amplifier (21) is coated with a film having a reflectivity of the optical signal higher than 90%.

4. The integrated narrow linewidth laser on chip of claim 1 wherein the first micro-ring resonator (201) comprises: the optical coupler (4), the phase shifter (5), the optical coupler (6), the phase shifter (7), the optical coupler (8), the phase shifter (9) and the optical coupler (10) are connected in the following mode: the optical coupler (4) is connected with the phase shifter (5), the phase shifter (5) is connected with the optical coupler (6), the optical coupler (6) is connected with the phase shifter (7), the phase shifter (7) is connected with the optical coupler (8), the optical coupler (8) is connected with the phase shifter (9), and the phase shifter (9) is connected with the optical coupler (10);

the optical coupler (4) is connected with the optical coupler (6), the optical coupler (8) is connected with the optical coupler (10), and the optical coupler (4) is connected with the optical coupler (10);

the second microring resonator (202) includes: an optical coupler (11), a phase shifter (12), an optical coupler (13), an optical coupler (14), a phase shifter (15), an optical coupler (16) and a phase shifter (17) are connected in the following modes: the optical coupler (11) is connected with the phase shifter (12), the phase shifter (12) is connected with the optical coupler (13), the optical coupler (13) is connected with the optical coupler (14), the optical coupler (14) is connected with the phase shifter (15), the phase shifter (15) is connected with the optical coupler (16), and the optical coupler (16) is connected with the phase shifter (17);

the optical coupler (11) is connected with the optical coupler (13), the optical coupler (14) is connected with the optical coupler (16), and the optical coupler (11) is connected with the phase shifter (17);

the optical coupler (4) is connected with the phase shifter (3), the optical coupler (10) is connected with the optical coupler (11), and the optical coupler (16) is connected with the optical coupler (18).

5. The on-chip integrated narrow linewidth laser of claim 1, wherein the first micro-ring resonator (201) and the second micro-ring resonator (202) have different radii and free spectral ranges, forming an up-down-channel micro-ring resonator, and a vernier effect occurs when an optical signal propagating in the second sub-resonator (200) passes through the first micro-ring resonator (201) and the second micro-ring resonator (202), and only an optical signal satisfying a vernier effect filtering condition can continue to propagate.

6. The on-chip integrated narrow linewidth laser of claim 5 wherein the free spectral range of the first micro-ring resonator (201), the free spectral range of the second micro-ring resonator (202), the total free spectral range of the first micro-ring resonator (201) and the second micro-ring resonator (202) are related as follows:

wherein FSR (FSR) ₁ Is the free spectral range, FSR, of the first microring resonator (201) ₂ Is the free spectral range of the second micro-ring resonator (202), and FSR is the total free spectral range of the first micro-ring resonator (201) and the second micro-ring resonator (202).

7. An integrated narrow linewidth laser on chip according to claim 2, characterized in that a drive current is injected into the first (1) and second (21) reflective semiconductor optical amplifiers simultaneously.

8. A chip integrated narrow linewidth laser according to any one of claims 1 to 3, wherein the mach-zehnder interference structure (300) comprises the optical coupler (18), a phase shifter (20) and a Y-branch (19), the optical coupler (18) is connected to the phase shifter (20), the optical coupler (18) is connected to the Y-branch (19), the phase shifter (20) is connected to the Y-branch (19), the optical signal selected by the coupled resonator is output through the Y-branch (19), and the phase of the signal arm or the reference arm of the mach-zehnder interference structure (300) is changed by adjusting the current injected into the phase shifter (20), so that the optical signals of the signal arm and the reference arm interfere constructively when reaching the Y-branch (19), and the power of the output optical signal is increased.

9. The on-chip integrated narrow linewidth laser of claim 1 wherein the propagation conditions of the first sub-resonator (100) are: simultaneously meeting a preset resonance condition of the first sub-resonant cavity (100) and a preset reflection condition of the uniform grating (2);

the propagation conditions of the second sub-resonator (200) are: and simultaneously, the preset resonance condition of the second sub-resonant cavity (200), the preset reflection condition of the uniform grating (2), and vernier effect filtering conditions of the first micro-ring resonator (201) and the second micro-ring resonator (202) are met.