Narrow-linewidth multi-wavelength laser based on grating weak feedback and laser generation method

Abstract

The invention relates to a narrow-linewidth multi-wavelength laser based on grating weak feedback and a laser generation method, and the laser comprises a plurality of DFB chips which are used for outputting a plurality of groups of single-mode lasers; the external cavity feedback part is used for receiving the multiple groups of single-mode lasers to form reflected light and multi-wavelength transmission light; the light output structure is used for outputting narrow-linewidth multi-wavelength laser formed based on the multi-wavelength transmission light; the phase control parts are in one-to-one correspondence with the DFB chips and are used for adjusting the phase of the reflected light, so that the phase of the reflected light is matched with the phase of the light in the inner cavity of the DFB chip corresponding to the phase control parts; and the DFB chip is also used for realizing self-injection locking based on the reflected light transmitted back by the corresponding phase control part. The multi-wavelength long-width narrowing device has the advantage of realizing multi-wavelength long-width narrowing at low cost.

Description

Technical Field

[0001] The invention relates to the field of narrow linewidth lasers, and in particular to a narrow linewidth multi-wavelength laser based on grating weak feedback and a laser generating method. Background Art

[0002] In the era of big data, massive data interactions have put forward higher requirements on the communication capacity and transmission distance of modern communication technology and optical fiber communication systems. In order to meet the growing demand for network bandwidth and support the development of 5G and other new Internet services, expanding the capacity of the communication backbone network in an economical and efficient way is a key research direction. Among them, the large-capacity wavelength division multiplexing coherent communication system with multi-wavelength laser array as the core light source is an effective upgrade and expansion solution that meets this demand well.

[0003] However, in order to ensure accurate transmission of information in optical communication systems, coherent optical receiving systems also place higher requirements on the performance of the laser at the transmitting end. The damage of laser performance to the signal in coherent optical communication systems is mainly manifested in the frequency drift and phase noise of the laser at the transmitting end, which will cause aliasing and increase the complexity of the back-end digital signal processing algorithm. Take m-ary quadrature amplitude modulation (m-QAM) that can simultaneously modulate the amplitude information and phase information of the signal as an example: when the system adopts the Square 16QAM modulation format, the tolerance of its laser line width is about 120kHz, while when the Square 64QAM modulation format is adopted, the laser line width is required to be less than 10kHz.

[0004] It is not difficult to see that with the increase of modulation bases, the requirements for laser linewidth become more and more stringent. Therefore, the research on narrow-linewidth multi-wavelength light sources plays a key role in the development of coherent optical communications. However, how to achieve multi-wavelength linewidth narrowing at low cost is a difficult problem faced.

[0005] Some existing solutions use reflection from a microring resonator (MMR) on silicon photonics to narrow the linewidth. However, due to the strong feedback mechanism of the microring, the linewidth is in an extremely narrow working range during the process. The system is constantly faced with the situation of linewidth widening that may enter a chaotic state at any time, causing the light source to have a chaotic spectrum and disrupting the normal operation of the transmitter.

[0006] Therefore, it is urgent for technicians in this field to provide a narrow-linewidth multi-wavelength laser based on grating weak feedback, so that the process of narrowing the linewidth is in a wider working range, thereby reducing the quality requirements of the laser coupling process, so that multi-wavelength linewidth narrowing can be achieved at low cost. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a narrow-linewidth multi-wavelength laser based on grating weak feedback and a laser generation method.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A narrow linewidth multi-wavelength laser based on grating weak feedback, comprising:

[0010] Several DFB chips are used to output multiple groups of single-mode lasers;

[0011] An external cavity feedback part, used for receiving multiple groups of the single-mode lasers to form reflected light and multi-wavelength transmitted light;

[0012] A light output structure, used for outputting narrow line width multi-wavelength laser formed based on the multi-wavelength transmitted light;

[0013] A phase control unit, corresponding one-to-one to the DFB chip, for adjusting the phase of the reflected light so that the phase of the reflected light matches the phase of the cavity light inside the DFB chip corresponding to the phase control unit;

[0014] The DFB chip is also used to realize self-injection locking based on the reflected light transmitted back by the corresponding phase control unit.

[0015] Preferably, the external cavity feedback unit includes a weak feedback component and a wavelength division multiplexer;

[0016] One end of the wavelength division multiplexer is coupled to the phase control unit, and the other end is coupled to the weak feedback component. The wavelength division multiplexer is used to combine the single-mode lasers to output multi-wavelength combined light;

[0017] The weak feedback component comprises a grating reflector, and the grating reflector is used to receive the multi-wavelength combined light and output reflected light and multi-wavelength transmitted light;

[0018] The wavelength division multiplexer is also used to disperse the reflected light;

[0019] The phase control unit is used to receive and adjust the phase of the reflected light dispersed by the wavelength division multiplexer, and transmit it to the corresponding DFB chip.

[0020] Preferably, the weak feedback component further comprises a Mach-Zehnder interferometer, and a phase shifter is provided on an arm of the Mach-Zehnder interferometer;

[0021] The Mach-Zehnder interferometer is used to adjust the wavelength range of the reflected light and is also used to adjust the reflectivity change of the grating reflector.

[0022] Preferably, the grating reflector is arranged on an arm of the Mach-Zehnder interferometer.

[0023] Preferably, the grating reflector is configured as a distributed Bragg reflector or a fiber Bragg grating or a FBG optical fiber;

[0024] and / or

[0025] The reflectivity of the grating reflector is ≤10%.

[0026] Preferably, the grating reflector comprises a plurality of groups of gratings with different reflectivities;

[0027] Multiple groups of gratings are connected in series along the output direction of the optical path.

[0028] Preferably, the phase control unit and the external cavity feedback unit are integrated into an external cavity silicon photonic chip;

[0029] The DFB chip is butt-coupled or evanescently coupled with the external cavity silicon photonic chip.

[0030] Preferably, the DFB chip has an end face coupling region;

[0031] The end face coupling region adopts a wedge-shaped gradient edge coupler design.

[0032] Preferably, a plurality of the DFB chips are configured as a thin-film DFB multi-wavelength array unit heterogeneously integrated on silicon; the thin-film DFB multi-wavelength array unit, the phase control unit, and the external cavity feedback unit are integrated into an external cavity silicon photonic chip;

[0033] or,

[0034] The phase control unit and the wavelength division multiplexer are integrated in an external cavity silicon photonic chip. One end of the external cavity silicon photonic chip is coupled to the DFB chip, and the other end is coupled to the weak feedback component.

[0035] A laser generation method applicable to the above-mentioned narrow linewidth multi-wavelength laser based on grating weak feedback comprises the following steps:

[0036] Multiple DFB chips output multiple groups of single-mode lasers;

[0037] Combining and processing a plurality of groups of the single-mode lasers to form reflected light and multi-wavelength transmitted light;

[0038] Transmitting the reflected light to the corresponding DFB chip to achieve self-injection locking;

[0039] Based on the multi-wavelength transmitted light, a narrow line width multi-wavelength laser is output.

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

[0041] The narrow linewidth multi-wavelength laser based on grating weak feedback provided in the above technical solution can output multiple groups of single-film lasers through the DFB chip through the above solution. The single-mode laser can form and output reflected light and multi-wavelength transmitted light under the action of the external cavity feedback part, which can make the process of narrowing the linewidth of the laser within a wider working range and make the overall structure of the laser relatively simple, which can not only realize the output of narrow linewidth multi-wavelength laser, but also reduce the quality requirements of the laser coupling process, further reduce the coupling difficulty, and reduce the cost of the laser. Correspondingly, the laser generation method of the narrow linewidth multi-wavelength laser based on grating weak feedback can generate the target laser (narrow linewidth multi-wavelength laser) while reducing the cost of laser generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 This is a schematic structural diagram provided in the first embodiment of the present invention.

[0044] Figure 2 This is a schematic structural diagram provided in the second embodiment of the present invention.

[0045] Figure 3 This is a schematic structural diagram provided in the third embodiment of the present invention.

[0046] Figure 4 This is a schematic structural diagram provided in the fourth embodiment of the present invention.

[0047] Figure 5 This is a schematic structural diagram provided in the fifth embodiment of the present invention.

[0048] Figure 6 This is a schematic structural diagram provided in the sixth embodiment of the present invention.

[0049] Figure 7 This is a schematic structural diagram provided in the seventh embodiment of the present invention.

[0050] Description of reference numerals:

[0051] 1. DFB chip; 2. Wavelength division multiplexer; 3. Weak feedback component; 31. Grating reflector; 32. Mach-Zehnder interferometer; 4. Phase control unit; 100. External cavity silicon photonic chip. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0054] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] See also Figures 1 to 6 The embodiment of the present invention provides a narrow-linewidth multi-wavelength laser based on grating weak feedback, including a DFB chip 1, an external cavity feedback part, a phase control part 4 and a light output structure.

[0056] Specifically, the DFB chip 1 is used to output a single-mode laser, and a plurality of DFB chips 1 are provided, and the plurality of DFB chips 1 are arrayed to form a DFB chip array area. The external cavity feedback part is used to receive multiple groups of single-mode lasers to form reflected light and multi-wavelength transmitted light. The optical output structure is used to output a narrow-linewidth multi-wavelength laser (target laser) formed based on the multi-wavelength transmitted light. The phase control part 4 corresponds one-to-one to the DFB chip 1, and is used to adjust the phase of the reflected light so that the phase of the reflected light matches the phase of the internal cavity light of the DFB chip 1 corresponding to the phase control part 4. The DFB chip 1 is also used to achieve self-injection locking based on the reflected light transmitted back by the corresponding phase control part 4.

[0057] Multiple groups of single-mode lasers can be output through multiple groups of DFB chips 1. Under the action of the external cavity feedback unit and the phase control unit 4, the single-mode laser can narrow the line width of the laser within a wider working range and make the overall structure of the laser relatively simple, which can not only realize the output of narrow-linewidth multi-wavelength lasers, but also reduce the quality requirements of the laser coupling process, further reduce the coupling difficulty, and reduce the cost of the laser.

[0058] Embodiment 1

[0059] See also Figure 1 In this embodiment, the external cavity feedback part includes a wavelength division multiplexer 2 and a weak feedback component 3, wherein one end of the wavelength division multiplexer 2 is coupled to the phase control part 4, and the other end is coupled to the weak feedback component 3, and the weak feedback component 3 includes a grating reflector 31.

[0060] Specifically, the wavelength division multiplexer 2 is used to combine single-mode lasers to output multi-wavelength combined light, and the grating reflector 31 is used to receive the multi-wavelength combined light, wherein a portion is transmitted through the grating reflector 31, and then the multi-wavelength transmitted light is output, and the multi-wavelength transmitted light is the narrow line width multi-wavelength laser (target laser) output by the laser. The other portion is reflected by the grating reflector 31 to form reflected light. It can be known that the reflected light in this state is multi-wavelength reflected light, which is dispersed into several beams after being reflected back from the wavelength division multiplexer 2, and enters the corresponding phase control unit 4, which adjusts the phase of the input reflected light so that the phase of the reflected light matches the phase of the cavity light inside the DFB chip corresponding to the phase control unit, and then inputs the corresponding DFB chip 1 to achieve self-injection locking.

[0061] It can be understood that by outputting multiple groups of single-mode lasers through multiple DFB chips 1 and arranging a wavelength division multiplexer 2 and a weak feedback component 3 in the laser external cavity, the light can be superimposed in the external laser cavity, so that the mode hopping noise is suppressed, the laser can oscillate with a narrow linewidth, and then output narrow linewidth multi-wavelength laser.

[0062] In addition, the DFB chip 1, the wavelength division multiplexer 2, the weak feedback component 3, the phase control unit 4 and the optical output structure are all based on optical waveguides. The phase control unit 4 can achieve phase adjustment by applying current or heater coupling.

[0063] In this embodiment, each DFB chip 1 may include a III-V group-based material that provides gain for the laser, such as but not limited to indium phosphide (InP). The end faces of the plurality of DFB chips 1 may also be coated with high-reflection (HR) and the other end faces may be coated with antireflection (AR), in which case the internal laser cavity of the DFB chip 1 is formed by the pair of end faces.

[0064] join Figure 1 In this embodiment, the phase control unit 4, the wavelength division multiplexer 2 and the weak feedback component 3 are integrated in the external cavity silicon photonic chip 100; the DFB chip 1 is dock-coupled or evanescently coupled with the external cavity silicon photonic chip 100.

[0065] Specifically, the phase control unit 4, the wavelength division multiplexer 2 and the weak feedback component 3 can be implemented as a silicon-on-insulator (SOI) chip or a silicon nitride (SiN) or a planar light wave circuit (PLC) chip. In this case, the external cavity silicon photonic chip 100 is a SOI chip or a SiN chip or a PLC chip.

[0066] Furthermore, the DFB chip 1 has an end face coupling region; the end face coupling region adopts a wedge-shaped gradient edge coupler design, thereby being able to reduce the coupling loss between the DFB chip 1 and the external cavity silicon photonic chip 100 .

[0067] join Figure 1 In this embodiment, the weak feedback component 3 further includes a Mach-Zehnder interferometer 32 (composed of two 1*2 MMIs and two arms), and a phase shifter is provided on the arm of the Mach-Zehnder interferometer 32; the Mach-Zehnder interferometer 32 is used to adjust the wavelength range of the reflected light, and is also used to adjust the reflectivity change of the grating reflector 31. Due to the limitation of the preparation process on silicon, the grating reflector 31 can only achieve reflection in a wider wavelength range, and the Mach-Zehnder interferometer 32 (MZI) can provide a periodic FSR for the reflection spectrum, and finally become a periodic weak feedback reflection beam. Through the mutual cooperation of the Mach-Zehnder interferometer 32 and the grating reflector 31, the optimal reflectivity of the laser can be better adjusted during the test. By providing a phase shifter on the arm of the Mach-Zehnder interferometer 32, the feedback light intensity of the grating reflector 31 at a specific wavelength can be achieved by adjusting the phase shifter. When the feedback light intensity is adjusted to the optimum, the noise suppression effect will be the best, that is, the line width is the smallest. It can be seen from the Schawlow-Townes line width formula that the greater the light intensity, the narrower the line width.

[0068] In this embodiment, the grating reflector 31 is configured as a distributed Bragg reflector or a fiber Bragg grating.

[0069] Furthermore, the reflectivity of the grating reflector 31 is ≤10%. Specifically, the design of the grating reflector 31 follows the formula of basic grating design, which can be obtained by design calculation through relevant parameters of the entire laser.

[0070] See also Figure 1It can be seen that the light beam generated by each DFB chip 1 includes single-wavelength light (single-mode laser). After passing through the wavelength division multiplexer 2, multiple groups of single-wavelength light (single-mode laser) are combined into a combined light beam, which is fed back in the wider reflection spectrum of the grating reflector 31 and then transmitted back to the corresponding DFB chip 1. By designing the periodic FSR on the reflection spectrum, it can correspond to a specific wavelength that can achieve weak feedback, thereby achieving narrow linewidth multi-wavelength light beam emission at the transmission end (optical output structure). The Mach-Zehnder interferometer 32 added to the arm of the MZI can meet the different channel spacing of the wavelengths of the DFB chips 1 of multiple arrays.

[0071] Embodiment 2

[0072] See also Figure 2 Based on the above-mentioned embodiment 1, the difference of this embodiment is that: a plurality of DFB chips 1 are configured as a thin-film DFB multi-wavelength array part heterogeneously integrated on silicon; the thin-film DFB multi-wavelength array part, the phase control part 4, the wavelength division multiplexer 2 and the weak feedback component 3 are integrated in the external cavity silicon photonic chip 100.

[0073] Specifically, the on-chip thin-film laser manufacturing method of III-V group heterogeneous integration on silicon can be used to integrate the thin-film DFB multi-wavelength array part, the phase control part 4, the wavelength division multiplexer 2 and the weak feedback component 3, and evanescent coupling can be used between the thin-film DFB multi-wavelength array part and the phase control part 4 to reduce unnecessary reflections.

[0074] Compared with the first embodiment, in the present embodiment, there is no need to consider the coupling process of docking coupling between each DFB chip 1 and the external cavity silicon photonic chip 100. It is necessary to ensure very precise alignment in the vertical, horizontal, and inclined directions, and avoid the docking coupling being affected by unwanted reflections on the coupling surface, which can further reduce the coupling process requirements and further reduce costs.

[0075] Embodiment 3

[0076] See also Figure 3 Based on the above embodiment 1, the difference of this embodiment is that the grating reflector 31 is arranged on the arm of the Mach-Zehnder interferometer 32 .

[0077] Embodiment 4

[0078] See also Figure 4 Based on the above-mentioned embodiment 1, the difference of this embodiment is that: the weak feedback component 3 may not be provided with the Mach-Zehnder interferometer 32, and the grating reflector 31 includes multiple groups of gratings with different reflectivities; the multiple groups of gratings are connected in series in sequence along the output direction of the optical path, and the gratings with different reflection wavelengths are connected in series to form the locking mode of lasers with different wavelengths of the DFB chip 1.

[0079] Embodiment 5

[0080] See also Figure 5 Based on the above-mentioned embodiment 1, the difference of this embodiment is that the weak feedback component 3 may not be provided with a Mach-Zehnder interferometer 32, and at the same time, the grating reflector 31 of the weak feedback component 3 is not used to receive multi-wavelength combined light, but is used to receive a single-mode laser.

[0081] Specifically, the grating reflector 31 includes multiple groups of grating structures, each group of grating structures is set corresponding to a DFB chip 1, and most of the single-mode laser output by each group of DFB chips 1 is transmitted through the corresponding coupled grating structure, and is sequentially transmitted to the phase control unit 4 and the wavelength division multiplexer 2, and then directly output through the optical output structure. A small part is reflected back to the corresponding DFB chip 1 through the grating structure to achieve self-injection locking.

[0082] It can be known that the light penetrating the grating reflector 31 and the light reflected by the grating reflector 31 are determined by the reflectivity of the grating reflector 31 .

[0083] Embodiment 6

[0084] See also Figure 6 Based on the above-mentioned embodiment 1, in this embodiment, the phase control unit 4 and the wavelength division multiplexer 2 are integrated in the external cavity silicon photonic chip 100, one end of the external cavity silicon photonic chip 100 is coupled to the DFB chip 1, and the other end is coupled to the weak feedback component 3.

[0085] Furthermore, in this embodiment, the weak feedback component 3 may not be provided with the Mach-Zehnder interferometer 32, and the grating reflector 31 is provided as an FBG optical fiber, including an internal grating structure and a lens provided at the front end of the grating structure.

[0086] It is worth noting that the linewidth of a single wavelength light source (such as a laser) is the spectral width of the spectrum output by the light source at its full width at half maximum (full width half-maximum, FWHM). In the case where the light source is a multi-wavelength (MW) light source that produces a plurality of different wavelengths of light spaced apart in the spectrum, each of the different wavelengths of light has its corresponding linewidth. According to certain embodiments of the present technology, the narrow linewidth multi-wavelength light output by the multi-wavelength light source disclosed herein includes a plurality of different wavelengths of light spaced apart in the spectrum, wherein each light of a different wavelength spaced apart in the spectrum has a narrow emission linewidth of no more than 100 kHz and preferably several tens of kHz. However, depending on the implementation and system requirements, each light of a different wavelength spaced apart in the spectrum emitted by the narrow linewidth multi-wavelength light source disclosed herein may also have a linewidth greater than 100 kHz.

[0087] Embodiment 7

[0088] See also Figure 7Based on the above embodiment, this embodiment further provides a laser generation method of the narrow linewidth multi-wavelength laser based on the above grating weak feedback, which specifically includes the following steps:

[0089] S1: Multiple DFB chips output multiple groups of single-mode lasers;

[0090] S2: Combine and process multiple groups of single-mode lasers to form reflected light and multi-wavelength transmitted light;

[0091] S3.1: delivering the reflected light to the corresponding DFB chip to achieve self-injection locking;

[0092] S3.2: Output narrow linewidth multi-wavelength laser based on multi-wavelength transmitted light.

[0093] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A narrow linewidth multi-wavelength laser based on grating weak feedback, characterized in that: include: Several DFB chips are used to output multiple groups of single-mode lasers; An external cavity feedback part, used for receiving multiple groups of the single-mode lasers to form reflected light and multi-wavelength transmitted light; A light output structure, used for outputting narrow line width multi-wavelength laser formed based on the multi-wavelength transmitted light; A phase control unit, corresponding one-to-one to the DFB chip, for adjusting the phase of the reflected light so that the phase of the reflected light matches the phase of the cavity light inside the DFB chip corresponding to the phase control unit; The DFB chip is also used to realize self-injection locking based on the reflected light transmitted back by the corresponding phase control unit.

2. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 1, characterized in that: The external cavity feedback part includes a weak feedback component and a wavelength division multiplexer; One end of the wavelength division multiplexer is coupled to the phase control unit, and the other end is coupled to the weak feedback component. The wavelength division multiplexer is used to combine the single-mode lasers to output multi-wavelength combined light; The weak feedback component comprises a grating reflector, and the grating reflector is used to receive the multi-wavelength combined light and output reflected light and multi-wavelength transmitted light; The wavelength division multiplexer is also used to disperse the reflected light; The phase control unit is used to receive and adjust the phase of the reflected light dispersed by the wavelength division multiplexer, and transmit it to the corresponding DFB chip.

3. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 2, characterized in that: The weak feedback component further comprises a Mach-Zehnder interferometer, and a phase shifter is provided on an arm of the Mach-Zehnder interferometer; The Mach-Zehnder interferometer is used to adjust the wavelength range of the reflected light and is also used to adjust the reflectivity change of the grating reflector.

4. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 3, characterized in that: The grating reflector is arranged on the arm of the Mach-Zehnder interferometer.

5. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 2, characterized in that: The grating reflector is configured as a distributed Bragg reflector or a fiber Bragg grating or a FBG optical fiber; and / or The reflectivity of the grating reflector is ≤10%.

6. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 2, characterized in that: The grating reflector includes a plurality of groups of gratings with different reflectivities; A plurality of groups of gratings are connected in series along the output direction of the optical path.

7. A narrow linewidth multi-wavelength laser based on grating weak feedback according to any one of claims 1 to 6, characterized in that: The phase control unit and the external cavity feedback unit are integrated into an external cavity silicon photonic chip; The DFB chip is butt-coupled or evanescently coupled with the external cavity silicon photonic chip.

8. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 7, characterized in that: The DFB chip has an end face coupling region; The end face coupling region adopts a wedge-shaped gradient edge coupler design.

9. The narrow linewidth multi-wavelength laser based on grating weak feedback according to claim 2, characterized in that: Several of the DFB chips are configured as thin-film DFB multi-wavelength array units heterogeneously integrated on silicon; the thin-film DFB multi-wavelength array unit, the phase control unit, and the external cavity feedback unit are integrated into an external cavity silicon photonic chip; or, The phase control unit and the wavelength division multiplexer are integrated in an external cavity silicon photonic chip. One end of the external cavity silicon photonic chip is coupled to the DFB chip, and the other end is coupled to the weak feedback component.

10. A laser generation method applicable to the narrow linewidth multi-wavelength laser based on grating weak feedback as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Multiple DFB chips output multiple groups of single-mode lasers; Combining and processing a plurality of groups of the single-mode lasers to form reflected light and multi-wavelength transmitted light; Transmitting the reflected light to the corresponding DFB chip to achieve self-injection locking; Based on the multi-wavelength transmitted light, a narrow line width multi-wavelength laser is output.

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