A multi-wavelength narrow-linewidth laser

Abstract

The present invention relates to the field of optical communication technology and provides a multi-wavelength narrow-linewidth laser, wherein the multi-wavelength narrow-linewidth laser includes an arrayed waveguide grating filter, multiple semiconductor gain chips, and multiple comb filters; the semiconductor gain chip and the arrayed waveguide grating filter are also used to form a resonant cavity, so that broadband light resonates in the resonant cavity to form periodic multimode light; the comb filter and the output waveguide port constitute a mode selection filter to select single-mode light to resonate in the resonant cavity to form a narrow-linewidth laser; the arrayed waveguide grating filter also combines the single-mode narrow-linewidth laser to output a multi-wavelength narrow-linewidth laser. The present invention adopts a combined filtering method of an arrayed waveguide grating filter and a comb filter, which makes it easier to realize a mode selection filter with a narrower bandwidth, so that the linewidth of the output narrow-linewidth laser is narrower. While filtering the comb wave, the arrayed waveguide grating filter also acts as a wavelength division multiplexer to achieve a higher degree of integration.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a multi-wavelength narrow-linewidth laser. Background Art

[0002] Lasers of multiple wavelengths are widely used as working light sources in industry, medicine, and scientific research. These lights often need to be switched quickly or used simultaneously, and there are relatively high requirements for the spectral linewidth of the laser light source. However, in actual use, in many cases, laser replacement is not allowed or the working time is very short, which requires a multi-wavelength narrow-linewidth semiconductor laser.

[0003] Narrow-linewidth laser light sources feature ultra-long coherence lengths and ultra-low noise, and are widely used in ultra-high-precision coherent lidar, ship fiber-optic hydrophones, perimeter security and precision fiber-optic sensing, spacecraft docking, inter-satellite communications, and fiber-optic coherent communications. Currently, there are two main types of mature narrow-linewidth single-frequency laser products on the domestic and international markets: narrow-linewidth fiber lasers and narrow-linewidth semiconductor external cavity lasers. Both narrow-linewidth laser solutions have their own advantages and disadvantages in terms of performance. Specifically, narrow-linewidth fiber lasers tend to achieve higher output power and lower low-frequency phase noise than narrow-linewidth semiconductor external cavity lasers, but their environmental adaptability and performance stability are inferior to those of narrow-linewidth semiconductor external cavity lasers. Most commercial narrow-linewidth fiber lasers operate within a temperature range limited to 0-50°C. Furthermore, the output laser of narrow-linewidth fiber lasers contains significant relaxation oscillation peaks, resulting in significant intensity noise in the low-frequency range. Optical sensing and optical communications are urgently seeking to reduce the low-frequency intensity noise of narrow-linewidth fiber lasers. Narrow-linewidth semiconductor external cavity lasers are more widely used in the market due to their excellent environmental adaptability, ultra-low low-frequency relative intensity noise, low phase noise and small size.

[0004] like Figure 1 The figure shows a block diagram of the application of narrow-linewidth lasers at the transmitting end of an array optical sensing system. Single-frequency, narrow-linewidth lasers with wavelengths λ1, λ2, λ3, ..., λn are combined using wavelength division multiplexing (WDM) technology and then fed through fiber amplifiers into increasingly large optical sensing systems. In increasingly complex sensing systems, more complex systems employ more wavelengths and a greater variety of single-frequency lasers. This poses a significant challenge for payload-constrained systems such as spacecraft docking and inter-satellite communications. Improving the integration of multi-wavelength, narrow-linewidth semiconductor lasers is one of the current technological challenges.

[0005] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in this technical field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the integration level of multi-wavelength narrow-linewidth semiconductor lasers in the prior art is not high.

[0007] The present invention provides a multi-wavelength narrow linewidth laser, comprising an arrayed waveguide grating filter 1, a plurality of semiconductor gain chips 2 and a plurality of comb filters 3;

[0008] Each semiconductor gain chip 2 is optically coupled to a corresponding output waveguide port 11 in the arrayed waveguide grating filter 1, and a comb filter 3 is provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11;

[0009] The semiconductor gain chip 2 is used to emit broadband light. The semiconductor gain chip 2 and the arrayed waveguide grating filter 1 are also used to form a resonant cavity, so that the broadband light resonates in the corresponding resonant cavity to form periodic multimode light.

[0010] The comb filter 3 and the corresponding output waveguide port 11 of the arrayed waveguide fiber filter constitute a mode selection filter, and the mode selection filter is used to select the single-mode light of the corresponding wavelength from the periodic multimode light as the narrow-linewidth light, so that the narrow-linewidth light resonates in the resonant cavity to obtain maximum gain, thereby forming a narrow-linewidth laser of the corresponding wavelength;

[0011] The arrayed waveguide grating filter 1 is also used to combine single-mode narrow-linewidth lasers of different wavelengths to output multi-wavelength narrow-linewidth lasers.

[0012] Preferably, the semiconductor gain chip 2 is a reflective semiconductor gain chip;

[0013] The first end face of each semiconductor gain chip 2 is a total reflection surface, and the second end face of the arrayed waveguide grating filter 1 is a partial reflection surface, so that light is emitted back and forth between the first end face and the second end face, thereby forming the resonant cavity;

[0014] The first end face is the end face of the semiconductor gain chip 2 opposite to the transmission direction of the emitted broadband light, and the second end face is the end face where the input waveguide port 12 of the arrayed waveguide grating filter 1 is located;

[0015] Narrow linewidth lights of different wavelengths are combined by the arrayed waveguide grating filter 1 to form multi-wavelength narrow linewidth lights. The multi-wavelength narrow linewidth lights reach the second end face, which reflects the multi-wavelength narrow linewidth lights along the original path. The lights are then demultiplexed and filtered by the arrayed waveguide grating filter 1, and narrow linewidth lights of corresponding wavelengths are obtained at the output waveguide port 11. The second end face is used as a common reflection surface to form independent resonant cavities.

[0016] Preferably, the multi-wavelength narrow linewidth laser further includes a plurality of phase modulators 4;

[0017] A phase modulator 4 is provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11;

[0018] The phase modulator 4 is used to adjust the cavity length of the corresponding resonant cavity to adjust the cavity mode spectrum of the resonant cavity so that the peak of a single-mode light of the periodic multimode light is aligned with the peak of the combined spectrum, thereby selecting a single-mode light of the corresponding wavelength from the periodic multimode light to form a narrow-linewidth laser of the corresponding wavelength; wherein the combined spectrum is a spectrum obtained by combining the transmission spectrum of the comb filter 3 and the transmission spectrum of the corresponding output waveguide port 11.

[0019] Preferably, the transmission spectrum of the comb filter 3 is a multi-peak spectrum, and the transmission spectrum of the output waveguide port 11 of the arrayed waveguide fiber filter is a single-peak flat-top spectrum, and one peak of the multi-peak spectrum is aligned with the peak of the corresponding single-peak flat-top spectrum to form a single-peak combined spectrum.

[0020] Preferably, the output waveguide port 11 and the input waveguide port 12 of the arrayed waveguide grating filter 1 are arranged to be inclined at a preset angle in the same direction relative to the first optical path to improve the stability of the resonant cavity; wherein, the first optical path is the transmission optical path of the broadband light emitted by the corresponding semiconductor gain chip 2.

[0021] Preferably, a collimating component 5 and a coupling component 6 are further provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11;

[0022] The phase modulator 4 and the comb filter 3 are sandwiched between the collimating component 5 and the coupling component 6;

[0023] The collimating component 5 is disposed close to the semiconductor gain chip 2 and is used to collimate the broad spectrum light emitted by the semiconductor gain chip 2;

[0024] The coupling component 6 is disposed near the output waveguide port 11 and is used for coupling light.

[0025] Preferably, the multi-wavelength narrow linewidth laser further includes a lens 7;

[0026] The lens 7 is provided at the output end of the arrayed waveguide grating filter 1 and is used to adjust the divergence angle of the multi-wavelength narrow linewidth laser so that the multi-wavelength narrow linewidth laser is efficiently coupled and injected into the corresponding transmission optical fiber.

[0027] Preferably, the multi-wavelength narrow linewidth laser further includes an optical isolator 8;

[0028] The optical isolator 8 is provided at the output end of the arrayed waveguide grating filter 1 and is used to isolate light in a direction opposite to the transmission direction of the multi-wavelength narrow linewidth laser.

[0029] Preferably, in the periodic comb-shaped narrowband spectrum of the comb filter 3 , the interval between two adjacent peak wavelengths is consistent with the optical channel wavelength interval of the arrayed waveguide grating filter 1 .

[0030] Preferably, the end face where the output waveguide port 11 is located is coated with an anti-reflection film.

[0031] The present invention utilizes a combined arrayed waveguide grating (AWG) filter and a comb filter, making it technically easier to implement a narrower bandwidth mode-selective filter, thereby narrowing the output narrow-linewidth laser linewidth. Furthermore, the AWG filter, while filtering the comb wave, also functions as a wavelength division multiplexer, thus achieving a higher level of integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0033] Figure 1 This is a block diagram of an application of a narrow linewidth laser in the prior art at the transmitting end of an array optical sensing system provided by an embodiment of the present invention;

[0034] Figure 2 1 is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of the spectrum of a comb filter and an output waveguide port in a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0036] Figure 4 1 is a spectrum diagram of a cavity mode spectrum and a combined spectrum in a multi-wavelength narrow linewidth laser provided by an embodiment of the present invention;

[0037] Figure 5 1 is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of a resonant cavity formed by a first end face and a second end face in a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0039] Figure 7This is a schematic diagram of a resonant cavity formed by a first end face and a second end face in a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0040] Figure 8 1 is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0041] Figure 9 1 is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0042] Figure 10 1 is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention;

[0043] Figure 11 This is a schematic structural diagram of a multi-wavelength narrow-linewidth laser provided by an embodiment of the present invention.

[0044] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0045] 1. Arrayed waveguide grating filter; 11. Output waveguide port; 12. Input waveguide port; 2. Semiconductor gain chip; 3. Comb filter; 4. Phase modulator; 5. Collimation component; 6. Coupling component; 7. Lens; 8. Optical isolator. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] In the description of the present invention, the terms "inside", "outside", "longitudinal", "lateral", "upper", "lower", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0048] In the description of the present invention, the terms "output port" and "input port" are used to describe the transmission direction of light. Light is input from the input port and output from the output port.

[0049] It is important to distinguish between the terms "input waveguide port" and "output waveguide port." These terms are commonly used by those skilled in the art with respect to arrayed waveguide grating filters. At the two ends of an arrayed waveguide grating filter, the waveguide at the end with multiple waveguides is called the output waveguide, and its port is correspondingly called the "output waveguide port." The waveguide at the end with a single waveguide is called the input waveguide, and its port is correspondingly called the "input waveguide port." Light can be input from the "input waveguide port" and output from the "output waveguide port," or it can be output from the "input waveguide port" and input from the "output waveguide port." The above terms are used merely to facilitate the description of the present invention and do not require the present invention to be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0050] The terms "first", "second", "once" and "secondary" in the present invention do not have any special limiting meanings. They are used for description only to facilitate the description of different individuals in a category of objects, and should not be interpreted as having special limiting meanings in terms of order or other aspects.

[0051] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] Embodiment 1:

[0053] Embodiment 1 of the present invention provides a multi-wavelength narrow linewidth laser, such as Figure 2 As shown, it includes an arrayed waveguide grating filter 1, multiple semiconductor gain chips 2 and multiple comb filters 3.

[0054] Each semiconductor gain chip 2 is optically coupled to a corresponding output waveguide port 11 in the arrayed waveguide grating filter 1 , and a comb filter 3 is provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11 .

[0055] The semiconductor gain chip 2 is used to emit broadband light. The semiconductor gain chip 2 and the arrayed waveguide grating filter 1 are also used to form a resonant cavity, so that the broadband light resonates in the corresponding resonant cavity to form periodic multimode light.

[0056] The comb filter 3 and the corresponding output waveguide port 11 of the arrayed waveguide fiber filter constitute a mode selection filter, which is used to select single-mode light of corresponding wavelength from the periodic multimode light as narrow-linewidth light, so that the narrow-linewidth light resonates in the resonant cavity to obtain maximum gain, thereby forming a narrow-linewidth laser of corresponding wavelength.

[0057] The arrayed waveguide grating filter 1 is also used to combine single-mode narrow-linewidth lasers of different wavelengths to output multi-wavelength narrow-linewidth lasers.

[0058] The semiconductor gain chip serves as a seed source and a gain medium, and together with the resonant cavity, forms an external cavity laser. The comb filter 3 and the corresponding output waveguide port act as mode selection filters for the external cavity laser, thereby generating narrow-linewidth lasers. At the same time, the arrayed waveguide grating filter also acts as a combiner, ultimately outputting multi-wavelength narrow-linewidth lasers.

[0059] The number of output waveguide ports 11 of the arrayed waveguide grating filter 1 determines the maximum number of lights that can be multiplexed, and thus also determines the number of wavelengths in the output multi-wavelength narrow-linewidth laser light.

[0060] It should be noted here that the periodic multimode light and single-mode light do not refer to light at different stages in optical path transmission, but are described based on the working principle of the multi-wavelength narrow-linewidth laser provided in this embodiment. That is, when the semiconductor gain chip and the corresponding resonant cavity form a laser, the light in the resonant cavity of the laser is multimode light, but due to the introduction of the comb filter 3 and the arrayed waveguide fiber filter, the light in the resonant cavity is single-mode light, thereby obtaining a narrow-linewidth laser through resonance.

[0061] The spectrum of the periodic multimode light is the cavity mode spectrum of the resonant cavity, such as Figure 4 shown.

[0062] like Figure 3 As shown, the transmission spectrum of the comb filter 3 is a multi-peak spectrum (i.e. Figure 3 The transmission spectrum of the output waveguide port 11 of the arrayed waveguide fiber filter is a single-peak flat-top spectrum (i.e. Figure 3 A peak of the multi-peak spectrum is aligned with the peak of the corresponding single-peak flat-top spectrum to form a single-peak combined spectrum, that is, the transmission spectrum of the mode selection filter, such as Figure 4 As shown, under the action of the mode selection filter, when the combined spectrum (in Figure 4 When the peak of the periodic multimode light (expressed as a combined filtered spectrum) is aligned with the peak of a single-mode light in the cavity mode spectrum, the mode selective filter only allows one single-mode light in the periodic multimode light to be transmitted, thereby selecting the single-mode light of the corresponding wavelength, that is, the narrow linewidth light.

[0063] The peak of the combined spectrum is aligned with the peak of a single-mode light in the cavity mode spectrum by physically changing the distance between the semiconductor gain chip and the arrayed waveguide grating filter. When the distance changes, the cavity length of the resonant cavity changes, and thus the cavity mode spectrum of the resonant cavity changes, thereby adjusting the peak of the combined spectrum to align with the peak of a single-mode light in the cavity mode spectrum.

[0064] As an optional embodiment, the wavelength interval between adjacent peaks in the multi-peak spectrum of the comb filter 3 is the same as the optical channel interval of the arrayed waveguide grating filter. For example, in a hydrophone fiber optic sensing system, a comb filter 3 with a free spectrum range (i.e., the wavelength interval between adjacent peaks) of 200 GHz and an arrayed waveguide grating filter with an optical channel interval of 200 GHz are combined to produce a multi-wavelength narrow-linewidth laser.

[0065] In actual use, in order to improve the integration level, the plurality of semiconductor gain chips may be a semiconductor gain chip array.

[0066] The comb filter 3 can be an optical etalon, microring filter, or similar filter capable of outputting a comb-shaped multi-peak spectrum. Comb filter 3 preferably employs an optical etalon. By adjusting the incident angle, the peak wavelength of a multi-peak spectrum is aligned with the peak of a single-peak flat-top spectrum corresponding to output waveguide port 11, and also with the peak of a single-mode light in the cavity mode spectrum.

[0067] This embodiment utilizes a combined filtering method using an arrayed waveguide grating filter 1 and a comb filter 3. This makes it technically easier to implement a narrower bandwidth mode-selective filter, thereby achieving single-mode optical output and ultimately forming a narrow-linewidth laser. Furthermore, the arrayed waveguide grating filter 1 not only functions as a mode-selective filter for the laser, but also as a wavelength division multiplexer, combining narrow-linewidth lasers of different wavelengths, thereby achieving a higher level of integration.

[0068] Regarding the semiconductor gain chip 2 and the arrayed waveguide grating filter 1 in the above embodiment, which are also used to form a resonant cavity, this embodiment also provides an optional embodiment, such as Figure 5 As shown, specifically including:

[0069] The semiconductor gain chip 2 is a reflective semiconductor gain chip.

[0070] The first end face of each semiconductor gain chip 2 is a total reflection surface, and the second end face of the arrayed waveguide grating filter 1 is a partial reflection surface, so that light is emitted back and forth between the first end face and the second end face, thereby forming the resonant cavity.

[0071] The first end face is the end face of the semiconductor gain chip 2 opposite to the transmission direction of the emitted broadband light, and the second end face is the end face where the input waveguide port 12 of the arrayed waveguide grating filter 1 is located.

[0072] Narrow linewidth lights of different wavelengths are combined by the arrayed waveguide grating filter 1 to form multi-wavelength narrow linewidth lights. The multi-wavelength narrow linewidth lights reach the second end face, which reflects the multi-wavelength narrow linewidth lights along the original path. The lights are then demultiplexed and filtered by the arrayed waveguide grating filter 1, and narrow linewidth lights of corresponding wavelengths are obtained at the output waveguide port 11. The second end face is used as a common reflection surface to form independent resonant cavities.

[0073] The arrayed waveguide grating filter 1 comprises multiple output waveguides, an output star coupler, an arrayed waveguide, an input star coupler, and a single input waveguide. The wavelength spacing of the light output by the arrayed waveguide grating filter 1 is controlled by the phase difference between adjacent waveguides in the arrayed waveguide. The arrangement and specific implementation of the various components in the arrayed waveguide grating filter 1 are conventional and are not shown in the accompanying figures.

[0074] Each output waveguide corresponds to an output waveguide port 11, and each input waveguide corresponds to an input waveguide port 12. The output waveguide, input waveguide, input waveguide port 12, and output waveguide port 11 are conventional terms used by those skilled in the art to refer to the fixed ports of the arrayed waveguide grating filter 1, and do not refer to the input and output directions of light. In actual use, light can be input into the arrayed waveguide grating filter 1 from the output waveguide port 11 and output from the input waveguide port 12, thereby realizing the function of multi-light multiplexing; light can also be input into the arrayed waveguide grating filter 1 from the input waveguide port 12 and output from the arrayed waveguide grating filter 1 from the output waveguide port 11, thereby realizing the function of light demultiplexing.

[0075] An optional implementation of the first end face being a reflective surface and the second end face being a partially reflective surface is to coat the first and second end faces with corresponding reflective films (typically highly reflective films). Alternatively, the first and second end faces may be provided with corresponding reflective mirrors, wherein the second end face reflects light below a preset power and transmits light above a preset power. The preset power is determined by those skilled in the art based on analysis of the design requirements of the multi-wavelength narrow-linewidth laser.

[0076] The end face opposite to the first end face in the semiconductor gain chip (i.e., the end face close to the arrayed waveguide grating filter 1) is coated with an anti-reflection film, and the end face where each output waveguide port 11 of the arrayed waveguide grating filter is located is also coated with an anti-reflection film to increase the transmission of light in the resonant cavity.

[0077] In order to more clearly present the process of forming a resonant cavity by combining the first end face and the second end face, this embodiment further provides Figure 6 As shown, a schematic diagram of constructing a multi-wavelength narrow linewidth laser using N semiconductor gain chips 2 to ultimately generate a multi-wavelength narrow linewidth laser is shown. The multiple first end faces in the figure belong to the first semiconductor gain chip 2, the second semiconductor gain chip 2, ..., and the Nth semiconductor gain chip 2, respectively. When light is transmitted from the first end face to the second end face, the arrayed waveguide grating filter 1 plays a multiplexing role, combining the narrow linewidth lights of λ1, λ2, ..., λn. The multiplexed multi-wavelength narrow linewidth light is incident on the second end face. The second end face reflects the portion of light below the preset power and transmits the portion of light above the preset power. When the light is transmitted from the second end face to the first end face, The arrayed waveguide grating filter 1 performs a wavelength splitting function, dividing a portion of multi-wavelength narrow-linewidth light below a preset power into narrow-linewidth lights of λ1, λ2, ..., λn, and respectively reaching the corresponding output waveguide ports 11. Since the wavelength of the narrow-linewidth light does not change, the narrow-linewidth light is directly transmitted when passing through the output waveguide port 11. For the same reason, the narrow-linewidth light directly passes through the comb filter 3 and enters the corresponding semiconductor gain chip 2, reaching the corresponding first end face and being reflected again to the second end face. Through the back-and-forth reflection of light, the light is continuously excited in the resonant cavity, and finally, after rising to the preset power, it is emitted from the second end face. The emitted light is the multi-wavelength narrow-linewidth laser.

[0078] When the second end face is used to form a resonant cavity, although there are sections where multi-wavelength narrow-linewidth light is transmitted together, due to the wavelength division multiplexing of the arrayed waveguide grating filter 1, the narrow-linewidth light of each wavelength reaches the first end face of the corresponding semiconductor gain chip, thereby realizing multiple independent resonant cavities through one second end face and the first end face of each semiconductor gain chip.

[0079] On the other hand, since the second end face is located at the input waveguide port 12, the laser is provided with the physically longest resonant cavity under the integrated structure, so that the resonant cavity maximizes the use of the space inside the multi-wavelength narrow-linewidth laser, making the cavity length of the formed narrow-linewidth laser beam longer and the linewidth narrower, and through further multiplexing of the arrayed waveguide grating filter 1, the integration of its internal devices is improved, making its miniaturization possible.

[0080] In the above embodiment, a method is provided for aligning the peak of the combined spectrum with the peak of a single-mode light in the cavity mode spectrum by physically changing the distance between the semiconductor gain chip and the arrayed waveguide grating filter. However, in actual use, the presence of movable elements in the laser may cause the resonant cavity to be unstable, making the output wavelength of the laser unstable. To address this problem, this embodiment also provides the following preferred implementations, such as Figure 7 As shown, specifically including:

[0081] The multi-wavelength narrow-linewidth laser further includes a plurality of phase modulators 4 .

[0082] A phase modulator 4 is provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11 .

[0083] The phase modulator 4 is used to adjust the cavity length of the corresponding resonant cavity to adjust the cavity mode spectrum of the resonant cavity so that the peak of a single-mode light of the periodic multimode light is aligned with the peak of the combined spectrum, thereby selecting a single-mode light of the corresponding wavelength from the periodic multimode light to form a narrow-linewidth laser of the corresponding wavelength; wherein the combined spectrum is a spectrum obtained by combining the transmission spectrum of the comb filter 3 and the transmission spectrum of the corresponding output waveguide port 11.

[0084] The cavity mode wavelength is related to the phase of the light participating in the resonance, and thus can be changed by the phase modulator 4. The phase modulator 4 can be composed of an electro-optic crystal or a thermo-optic material, and controls the cavity mode spectrum of the resonant cavity by applying a slowly varying electrical signal in real time, so that the peak of a single-mode light in the cavity mode spectrum is continuously aligned with the combined spectrum in real time.

[0085] The phase modulator 4 can be arranged between the semiconductor gain chip 2 and the comb filter 3 . Another arrangement method is that the comb filter 3 and the phase modulator 4 are arranged in sequence on the wide-spectrum laser light path generated by the semiconductor gain chip 2 .

[0086] When the peak of the combined spectrum is aligned with the peak of a single-mode light in the cavity mode spectrum, the single-mode light will obtain minimum cavity mode loss in the resonant cavity, and the cavity mode wavelength with the minimum loss will obtain maximum gain in the resonant cavity, thereby suppressing other cavity mode wavelengths and forming a gain-rich narrow-linewidth single-mode laser output.

[0087] As a preferred implementation, the waveguide port of the arrayed waveguide grating filter 1 is designed to further reduce the reflection effect inside the waveguide grating filter and improve the mode stability of the semiconductor gain chip 22 of the present invention. Figure 8 As shown, specifically including:

[0088] The output waveguide port 11 and the input waveguide port 12 of the arrayed waveguide grating filter 1 are arranged to be inclined at a preset angle in the same direction relative to the first optical path to improve the stability of the resonant cavity; wherein, the first optical path is the transmission optical path of the broadband light emitted by the corresponding semiconductor gain chip 2.

[0089] The preset angle is obtained by those skilled in the art based on analysis of the structural characteristics of the arrayed waveguide grating filter 1 .

[0090] As a preferred embodiment, Figure 9As shown, a collimating lens and a coupling lens are further provided between each semiconductor gain chip 2 and the corresponding output waveguide port 11 .

[0091] The collimating lens is a specific implementation of the collimating component 5 in product form, and the coupling lens is a specific implementation of the coupling component 6 in product form.

[0092] The phase modulator 4 and the comb filter 3 are sandwiched between the collimating lens and the coupling lens; the phase modulator 4 and the comb filter 3 are coaxially arranged at any position of the optical path between the collimating lens and the coupling lens.

[0093] The collimating component 5 is disposed close to the semiconductor gain chip 2 and is used to collimate the broad-spectrum light emitted by the semiconductor gain chip 2 .

[0094] The coupling component 6 is disposed near the output waveguide port 11 and is used for coupling light.

[0095] like Figure 10 As shown, the multi-wavelength narrow-linewidth laser further includes a lens 7 .

[0096] The lens 7 is arranged at the output end of the arrayed waveguide grating filter 1 and is used to adjust the divergence angle of the multi-wavelength narrow linewidth laser so that the multi-wavelength narrow linewidth laser is efficiently coupled into the corresponding transmission optical fiber.

[0097] In order to prevent the reverse transmission of light in the optical fiber from affecting the stable operation of the multi-wavelength narrow linewidth laser, such as Figure 10 As shown, the multi-wavelength narrow-linewidth laser further includes an optical isolator 8 .

[0098] The optical isolator 8 is provided at the output end of the arrayed waveguide grating filter 1 and is used to isolate light in a direction opposite to the transmission direction of the multi-wavelength narrow linewidth laser.

[0099] On the basis of the above embodiments, there is also a preferred embodiment, such as Figure 11 As shown, the comb filter 3 is located in the output waveguide port 11 of the arrayed waveguide grating filter 1. Specifically, the port of the output waveguide port 11 is designed as a waveguide grating; wherein the waveguide grating of each output waveguide port 11 has a different peak wavelength.

[0100] This preferred embodiment uses the waveguide grating on the arrayed waveguide grating filter 1 to realize the function of the comb filter 3, so that the devices required for the multi-wavelength narrow linewidth laser described in this embodiment are further reduced, thereby further improving the integration of the product.

Claims

1. A multi-wavelength narrow linewidth laser, characterized in that: It includes an arrayed waveguide grating filter (1), a plurality of semiconductor gain chips (2), and a plurality of comb filters (3); Each semiconductor gain chip (2) is optically coupled to a corresponding output waveguide port (11) in the arrayed waveguide grating filter (1), and a comb filter (3) is provided between each semiconductor gain chip (2) and the corresponding output waveguide port (11); The semiconductor gain chip (2) is used to emit broadband light, and the semiconductor gain chip (2) and the arrayed waveguide grating filter (1) are also used to form a resonant cavity, so that the broadband light resonates in the corresponding resonant cavity to form periodic multimode light; The comb filter (3) and the corresponding output waveguide port (11) of the arrayed waveguide grating filter (1) form a mode selection filter, and the mode selection filter is used to select single-mode light of corresponding wavelength from the periodic multi-mode light as narrow-linewidth light, so that the narrow-linewidth light resonates in the resonant cavity to obtain maximum gain, thereby forming a narrow-linewidth laser of corresponding wavelength; The arrayed waveguide grating filter (1) is also used to combine single-mode narrow-linewidth lasers of different wavelengths to output multi-wavelength narrow-linewidth lasers; The semiconductor gain chip (2) is a reflective semiconductor gain chip; The first end face of each semiconductor gain chip (2) is a total reflection surface, and the second end face of the arrayed waveguide grating filter (1) is a partial reflection surface, so that light is emitted back and forth between the first end face and the second end face, thereby forming the resonant cavity; The first end face is the end face of the semiconductor gain chip (2) opposite to the transmission direction of the emitted broadband light, and the second end face is the end face where the input waveguide port (12) of the arrayed waveguide grating filter (1) is located; Narrow linewidth lights of different wavelengths are combined by the arrayed waveguide grating filter (1) to form multi-wavelength narrow linewidth lights. The multi-wavelength narrow linewidth lights reach the second end face, and the second end face reflects the multi-wavelength narrow linewidth lights along the original path, and is split and filtered by the arrayed waveguide grating filter (1), and narrow linewidth lights of corresponding wavelengths are obtained at the output waveguide port (11), so that the second end face serves as a common reflection surface to form independent resonant cavities.

2. The multi-wavelength narrow linewidth laser according to claim 1, characterized in that: The multi-wavelength narrow linewidth laser further includes a plurality of phase modulators (4); A phase modulator (4) is provided between each semiconductor gain chip (2) and the corresponding output waveguide port (11); The phase modulator (4) is used to adjust the cavity length of the corresponding resonant cavity to adjust the cavity mode spectrum of the resonant cavity so that the peak of a single-mode light of the periodic multi-mode light is aligned with the peak of the combined spectrum, thereby selecting the single-mode light of the corresponding wavelength from the periodic multi-mode light to form a narrow linewidth laser of the corresponding wavelength; wherein the combined spectrum is a spectrum obtained by combining the transmission spectrum of the comb filter (3) and the transmission spectrum of the corresponding output waveguide port (11).

3. The multi-wavelength narrow linewidth laser according to claim 1, characterized in that: The transmission spectrum of the comb filter (3) is a multi-peak spectrum, the transmission spectrum of the output waveguide port (11) of the arrayed waveguide grating filter (1) is a single-peak flat-top spectrum, and one peak of the multi-peak spectrum is aligned with the peak of the corresponding single-peak flat-top spectrum to form a single-peak combined spectrum.

4. The multi-wavelength narrow linewidth laser according to claim 1, characterized in that: The output waveguide port (11) and the input waveguide port (12) of the arrayed waveguide grating filter (1) are arranged to be inclined at a preset angle in the same direction relative to a first optical path, so as to improve the stability of the resonant cavity; wherein the first optical path is a transmission optical path for the broadband light emitted by the corresponding semiconductor gain chip (2).

5. The multi-wavelength narrow linewidth laser according to any one of claims 1 to 4, characterized in that: A collimating component (5) and a coupling component (6) are also provided between each semiconductor gain chip (2) and the corresponding output waveguide port (11); The phase modulator (4) and the comb filter (3) are sandwiched between the collimating component (5) and the coupling component (6); The collimating component (5) is arranged close to the semiconductor gain chip (2) and is used to collimate the broad spectrum light emitted by the semiconductor gain chip (2); The coupling component (6) is arranged close to the output waveguide port (11) and is used for coupling light.

6. The multi-wavelength narrow linewidth laser according to any one of claims 1 to 4, characterized in that: The multi-wavelength narrow linewidth laser further includes a lens (7); The lens (7) is arranged at the output end of the arrayed waveguide grating filter (1) and is used to adjust the divergence angle of the multi-wavelength narrow linewidth laser so that the multi-wavelength narrow linewidth laser is emitted into the corresponding transmission optical fiber.

7. The multi-wavelength narrow linewidth laser according to any one of claims 1 to 4, characterized in that: The multi-wavelength narrow linewidth laser further includes an optical isolator (8); The optical isolator (8) is arranged at the output end of the arrayed waveguide grating filter (1) and is used to isolate light in a direction opposite to the transmission direction of the multi-wavelength narrow linewidth laser.

8. The multi-wavelength narrow linewidth laser according to any one of claims 1 to 4, characterized in that: In the periodic comb-shaped narrowband spectrum of the comb filter (3), the interval between two adjacent peak wavelengths is consistent with the optical channel wavelength interval of the arrayed waveguide grating filter (1).

9. The multi-wavelength narrow linewidth laser according to any one of claims 1 to 4, characterized in that: The end face where the output waveguide port (11) is located is plated with an anti-reflection film.

Images