A multi-wavelength laser based on injection locking

Abstract

The present invention relates to the field of integrated laser technology, specifically providing a multi-wavelength laser based on injection locking. Multiple lasers with different operating wavelengths are integrated into the waveguide layer of a single chip, and a corresponding microring is disposed at the rear end of each laser. Each laser forms an injection-locked relationship with the microring in its optical path. A multi-channel coupler and amplifier are then used to combine and amplify the optical signals, enabling multiple lasers to output optical signals with equal wavelength spacing. This invention integrates the laser, microring, coupler, and amplifier on the same chip, avoiding the drawbacks of traditional standalone lasers, such as the large space required and the inability to achieve extremely low linewidth. Injection locking improves the stability of the laser wavelength spacing, ensuring high precision and adjustability of the multi-wavelength output.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated lasers, and in particular relates to a multi-wavelength laser based on injection locking. Background Art

[0002] With the rapid development of information and communication technologies, especially in optical communications, the demand for data transmission rates and spectral efficiency continues to increase. As a core light source, narrow-linewidth, multi-wavelength lasers are widely used in high-speed optical communications, spectral analysis, sensing, lidar, and other fields. Narrow-linewidth, multi-wavelength integrated lasers offer advantages such as excellent coherence and compact size, enabling higher signal-to-noise ratios and lower bit error rates. Therefore, they have become a crucial component in modern optical communication systems and precision measurement.

[0003] However, in practical applications, traditional multi-wavelength lasers face some challenges. Common technical solutions usually rely on multiple independent lasers or tunable laser arrays. These systems usually require relatively complex optical components and precise adjustment mechanisms, resulting in large size, high cost, and high power consumption. In multi-wavelength lasers, since laser sources of different wavelengths have different stability and phase noise, it is difficult to achieve precise wavelength control. In particular, when multiple wavelengths are required for output, the wavelength spacing is difficult to accurately control, which affects system performance. In addition, multi-wavelength laser arrays in the prior art usually use discrete structures and on-chip integrated structures. Multiple discrete lasers need to be adjusted and aligned separately, resulting in low coupling efficiency between light sources, resulting in large light loss, and due to the large number of light sources, the overall integration is low, which is not conducive to miniaturization and low-cost design. Multi-wavelength array light sources with on-chip integrated structures cannot achieve narrow linewidths. Although the prior art has made certain progress in the design of multi-wavelength lasers, there are still problems such as difficulty in accurately controlling the wavelength spacing, low system integration, large size and cost. Existing technical solutions often fail to effectively address the challenges of narrow-linewidth multi-wavelength lasers in terms of integration, wavelength control accuracy and power consumption. Summary of the Invention

[0004] In view of this, the present invention aims to provide a multi-wavelength laser based on injection locking, which overcomes the problems of large light source volume, small number of laser light waves, large linewidth, and difficult to control wavelength spacing in the prior art through integrated design, and realizes on-chip integrated tunable narrow linewidth and equally spaced multi-wavelength laser output, and realizes precise control and stability maintenance of wavelength spacing through injection locking.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The present invention provides a multi-wavelength laser based on injection locking, comprising: integrated in the same chip waveguide layer:

[0007] An N×1 laser array comprising N lasers for generating light of different wavelengths;

[0008] Microring: Each laser has a microring on its rear optical path, and each laser forms an injection-locked relationship with the microring on its optical path.

[0009] The multi-channel coupler is arranged on the rear optical path of the micro-ring and is used to combine the optical signals output by N micro-rings.

[0010] Preferably, the multi-channel coupler is an N×1-port multi-channel interference coupler, an arrayed waveguide grating (AWG) or a fiber grating (FBG) coupler.

[0011] Preferably, a semiconductor optical amplifier, an erbium-doped fiber amplifier or a Raman amplifier is provided on the rear optical path of the output port of the multi-channel coupler.

[0012] Preferably, the lasers in the N×1 laser array are all DFB single-mode lasers or DBR single-mode lasers.

[0013] Preferably, each laser in the N×1 laser array is provided with a grating structure, and the feedback and selection characteristics of the optical signal are adjusted by changing the period of the grating structure, so that the N lasers output optical signals with equal wavelength intervals.

[0014] Preferably, it includes a substrate, a lower cladding layer, a waveguide layer, an upper cladding layer and an electrode layer in sequence.

[0015] Preferably, the circumferences of the microrings on the rear optical paths of different lasers are different. By adjusting the circumferences of different microrings, the resonance frequencies of the N microrings are evenly distributed at equal intervals.

[0016] Preferably, when the optical signal output by each laser is input into the microring, the optical signal matching the resonant frequency of the microring is emitted from the output port of the microring, and the optical signals of other frequencies are reflected back to the laser by the microring, so that the frequency of the optical signal output by the microring is locked to the resonant frequency of the microring.

[0017] Preferably, the method further includes: monitoring the resonant frequency of each microring, and when the resonant frequency of the microring deviates from its corresponding set working wavelength, performing closed-loop feedback control on the microring so that the resonant frequency of the microring tracks the set working wavelength to maintain an injection-locked state.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0019] This invention integrates multiple lasers with a microring on-chip and utilizes injection locking technology to achieve more precise wavelength control. This effectively reduces the laser linewidth, improves the stability of the laser wavelength spacing, and ensures high precision and adjustability of multi-wavelength output. This on-chip integration of the laser and microring overcomes the problems of traditional multi-wavelength light sources, which rely on the combination and adjustment of multiple independent lasers and optical components, resulting in large system size, complex structure, and low integration.

[0020] The present invention also integrates the coupler and amplifier on a single chip platform, which not only improves the efficiency of power amplification but also ensures that the laser signal maintains good coherence and spectral characteristics during the amplification process. Traditional multi-wavelength laser systems usually require external amplifiers to enhance the optical signal, which introduces additional losses and reduces the integration level.

[0021] In addition, the present invention actively compensates for the problem of microring resonance frequency mismatch caused by photomechanical effects and environmental drift through closed-loop feedback control. Through closed-loop adjustment, the microring resonance frequency always tracks the operating wavelength of the laser, maintaining a bidirectional injection locking state, and greatly improving the laser output stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 Schematic diagram of the waveguide layer structure of a multi-wavelength laser based on injection locking according to an embodiment of the present invention;

[0024] Figure 2 1 is a schematic structural diagram of a multi-wavelength laser based on injection locking without an adjustment electrode provided in an embodiment of the present invention;

[0025] Figure 3 3 is a schematic diagram of the structure of a multi-wavelength laser based on injection locking with an adjustment electrode provided in accordance with an embodiment of the present invention.

[0026] Reference numerals include:

[0027] Substrate 1, lower cladding 2, laser 31, microring 32, multi-channel coupler 33, amplifier 34, upper cladding 4, electrode layer 5. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0029] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying 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 a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0033] See also Figure 1 、 Figure 2 and Figure 3 In one embodiment of the present invention, a silicon photonics-integrated tunable narrow-linewidth multi-wavelength laser based on injection-locking technology is provided. The laser 31, microring 32, multi-channel coupler 33, and amplifier 34 are all integrated into the waveguide layer of the same chip. Specifically, from the perspective of material layering, the laser comprises, from bottom to top, a substrate 1, a lower cladding 2, a waveguide layer, an upper cladding 4, and an electrode layer 5. Substrate 1 is a silicon-based material that provides mechanical support. During the fabrication process, a layer of silicon dioxide is deposited on the upper surface of substrate 1 by deposition, serving as the lower cladding 2 of the waveguide layer. The silicon dioxide material creates a refractive index difference with the high-refractive-index waveguide layer material, confining the light field within the waveguide layer and preventing light field leakage. A layer of waveguide material is deposited on the upper surface of the lower cladding 2. Optional waveguide materials include, but are not limited to, silicon (Si), silicon nitride (SiNx), lithium niobate (LiNbO3), and other polymers. After the waveguide material is deposited, the laser 31, microring 32, multi-channel coupler 33, and amplifier 34 are integrated into the waveguide layer using photolithography and etching processes. Specifically, the waveguide layer is first fabricated using photolithography and etching according to the optical transmission design. The microring 32 is then partially removed to obtain the microring 32, resulting in a silicon-based monolithic integrated waveguide layer substrate.

[0034] The laser 31 and the amplifier 34 are prepared by growing III-V semiconductor epitaxial wafers using MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy). The epitaxial wafers respectively include a substrate, a confinement layer, a waveguide layer, an active region, and a waveguide layer.

[0035] The surface grating structure of the laser, as well as the ridge waveguide structure of the laser 31 and the amplifier 34, are prepared on the surface of the epitaxial wafer through photolithography and etching processes. The epitaxial wafer is then thinned and polished. The epitaxial wafer is then bonded to a silicon-based monolithic integrated waveguide layer substrate. During the bonding process, the light inlet and light outlet of the waveguide are aligned. The bonding process can use molecular bonding or polymer bonding to form a silicon-based monolithic integrated chip. An upper cladding layer 4 is further epitaxially prepared on the formed silicon-based monolithic integrated chip. Electrode patterns are then prepared on the upper cladding layer 4 using processes such as photolithography, etching, chemical vapor deposition, and magnetron sputtering to obtain an electrode layer 5. The electrode layer 5 includes electrodes corresponding to the laser 31, electrodes corresponding to the microring 32, and electrodes corresponding to the amplifier 34, completing the process preparation of a tunable narrow-linewidth multi-wavelength laser based on injection-locked silicon photonic integration.

[0036] To achieve narrow-linewidth, equally spaced, multi-wavelength output, this embodiment of the present invention fabricates an N×1 laser array within the waveguide layer of a single chip. This array consists of N lasers 31 capable of generating light of different wavelengths. A grating structure is fabricated on the surface of laser 31. By varying the surface grating period and selecting the mode, its feedback and selectivity characteristics for the optical signal are adjusted, thereby enabling fixed-interval wavelength selection. This allows these N lasers 31 to output multiple lasers of different wavelengths at equal intervals. This laser array can achieve frequency spacings ranging from 10 MHz to several hundred GHz. In this embodiment of the present invention, laser 31 utilizes a DFB single-mode laser. This can be replaced with a DBR single-mode laser or other single-mode laser as needed to provide narrow-linewidth laser output.

[0037] An N×1 microring array is installed in the optical path behind the N×1 laser array. The microring array includes N microrings 32 of varying circumferences. Specifically, each laser 31 has a microring 32 in its optical path. The circumferences of the microrings 32 in the optical paths behind different lasers 31 vary. By adjusting the circumferences of the different microrings 32, each microring 32 is matched to its corresponding laser 31, and the resonant frequencies of the N microrings 32 are evenly spaced and distributed with respect to the laser 31. Because the microring's transmission spectrum exhibits periodic dips, only optical signals with frequencies matching the resonant frequency of the microring 32 can resonate within the microring and be emitted from the output port of the microring 32. This enhances only optical signals near the resonant frequency of the microring, while optical signals at off-resonant frequencies are reflected back to the laser 31, forming an injection feedback loop. The optical signal reflected from the microring 32 carries its phase information, synchronizing the phase of the laser 31 to its resonant phase, effectively suppressing the phase noise of the laser 31. Alternatively, a fiber Bragg grating (FBG) or integrated optical waveguide filter can be used in place of the microring 32 for narrow linewidth control. Such filters can selectively narrow the linewidth of the output laser light by precisely adjusting their reflection spectrum. Compared to traditional filters that passively filter light without a feedback mechanism, the microring 32 forms an injection-locked relationship with the laser 31, providing strong phase feedback and actively correcting the phase noise of the laser 31. Once the output frequency of the laser 31 optical signal is locked near the resonant frequency of the microring 32 resonator, the frequency of the laser 31 output light stabilizes, forming an injection-locked state, thereby significantly narrowing the light source linewidth.

[0038] As an optional embodiment, fluctuations in the optical power injected into microring 32 by laser 31 (e.g., laser output drift due to changes in ambient temperature) can directly perturb the resonant frequency of microring 32 through the photomechanical effect, disrupting the original locked state. Therefore, embodiments of the present invention can also incorporate closed-loop feedback control based on injection locking, actively compensating for the photomechanical effect and environmental drift through tunable electrodes on the electrode layer 5 of microring 32. Specifically, microring 32 is made of lithium niobate, and the position of the resonant frequency in the transmission spectrum is monitored in real time at the output end of microring 32. When the resonant frequency of microring 32 deviates from its corresponding set operating wavelength, a closed-loop feedback loop is output to measure the resonant frequency deviation error. Based on the resonant frequency deviation, the electrodes corresponding to microring 32 in electrode layer 5 are adjusted. By adjusting the voltage applied to the electrodes, the lithium niobate material undergoes an electro-optical effect, which in turn changes the refractive index of microring 32. This causes the resonant frequency of microring 32 to track the set operating wavelength, maintaining the injection-locked state and improving the stability of the laser output of the multi-wavelength laser.

[0039] In this embodiment of the present invention, laser 31 and microring 32 in its optical path form an injection-locked relationship. Essentially, laser 31 is equivalent to a master light source, and microring 32 is equivalent to a slave light source. A multichannel coupler 33 with N×1 ports is connected to the optical path behind microring 32 to combine the light sources. Multichannel coupler 33 can be a multimode interference coupler (MMI), an AWG-based coupler (arrayed waveguide grating), or a fiber Bragg grating-based coupler. The coupler further enables wavelength-selective coupling of optical signals.

[0040] In this embodiment of the present invention, to reduce the adverse effects of coupling and transmission losses between multiple optical paths in the on-chip light source, an amplifier 34 (SOA) is connected to the output of the multi-channel coupler 33 to amplify the coupled optical signal. The multi-channel coupler 33 and amplifier 34 achieve the output of N equally spaced, narrow-linewidth, multi-wavelength light sources, achieved by injection-locking N lasers 31 and N microrings 32. Compared to traditional multi-wavelength lasers that require an external SOA, this embodiment of the present invention integrates the SOA directly on-chip, avoiding the losses introduced by external amplifiers. This design not only improves power amplification efficiency but also ensures that the optical signal maintains good coherence and spectral characteristics during amplification, further enhancing the overall performance of the multi-wavelength laser. Furthermore, lasers 31 and microrings 32 can be added or removed as needed to achieve output of more or fewer wavelengths, enhancing design flexibility. Furthermore, by controlling the voltages of the electrodes corresponding to different lasers 31 on the electrode layer 5, some lasers 31 can be disabled, enabling flexible adjustment of laser output. The voltage applied to the corresponding electrode of the amplifier 34 on the electrode layer 5 can also be adjusted to adjust the amplification gain and change the laser output power.

[0041] The multi-wavelength laser based on injection locking provided by the embodiment of the present invention solves the problems existing in traditional multi-wavelength lasers, such as a small number of laser light waves, a large linewidth, and difficulty in controlling the wavelength spacing. The laser multi-wavelength laser of the present invention can output tunable narrow-linewidth equally spaced multi-wavelength lasers, and realize precise control of the wavelength spacing and maintenance of stability, so as to meet the needs of high-speed communication, spectral analysis, precision sensing and other fields for multi-wavelength narrow-linewidth lasers.

[0042] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification shall be included in the scope of protection of this specification.

[0043] The systems, devices, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0044] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0045] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

Claims

1. A multi-wavelength laser based on injection locking, characterized in that: Includes integrated waveguide layers on the same chip: An N×1 laser array comprising N lasers for generating light of different wavelengths; Microring: Each laser has a microring on its rear optical path, and each laser forms an injection-locked relationship with the microring on its optical path. The multi-channel coupler is arranged on the rear optical path of the micro-ring and is used to combine the optical signals output by N micro-rings.

2. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: The multi-channel coupler is an N×1 port multi-channel interference coupler, an arrayed waveguide grating or a fiber grating coupler.

3. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: A semiconductor optical amplifier, an erbium-doped fiber amplifier or a Raman amplifier is provided on the rear optical path of the output port of the multi-channel coupler.

4. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: The lasers in the N×1 laser array are all DFB single-mode lasers or DBR single-mode lasers.

5. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: The lasers in the N×1 laser array are all provided with a grating structure. By changing the period of the grating structure to adjust the feedback and selection characteristics of the optical signal, the N lasers are made to output optical signals with equal wavelength intervals.

6. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: It includes a substrate, a lower cladding layer, the waveguide layer, an upper cladding layer and an electrode layer in sequence.

7. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: The circumferences of the microrings on the optical paths at the rear ends of different lasers are different. By adjusting the circumferences of different microrings, the resonance frequencies of N microrings are evenly distributed at equal intervals.

8. The multi-wavelength laser based on injection locking according to claim 1, characterized in that: When the optical signal output by each laser is input into the microring, the optical signal matching the resonant frequency of the microring is emitted from the output port of the microring, and the optical signals of other frequencies are reflected back to the laser by the microring, so that the frequency of the optical signal output by the microring is locked to the resonant frequency of the microring.

9. The multi-wavelength laser based on injection locking according to claim 8, characterized in that: Also includes: The resonant frequency of each microring is monitored. When the resonant frequency of the microring deviates from its corresponding set working wavelength, closed-loop feedback control is used to make the resonant frequency of the microring track the set working wavelength and maintain the injection-locked state.

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