Multi-channel interference multiplexing external cavity laser chip
By encapsulating RSOA array chips with different center gain wavelengths in an external cavity laser, and combining them with phase shifters and optical delay line arrays, flexible output and precise tuning of multi-wavelength optical signals from a multi-channel interferometric multiplexing external cavity laser chip are achieved. This solves the shortcomings of existing lasers in wavelength tuning and control, and improves the flexibility and stability of the system.
Patent Information
- Application Number
- CN202511654192.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-12
- Publication Date
- 2026-02-17
AI Technical Summary
Existing multi-channel interferometric lasers exhibit insufficient flexibility and efficiency in applications requiring dense wavelength division multiplexing and precise wavelength tuning. Furthermore, existing external cavity lasers require highly precise control technology to achieve wavelength selection, increasing the complexity and cost of system calibration and making it impossible to achieve dynamic tuning and flexible control of multiple wavelengths.
A multi-channel interference multiplexing external cavity optical amplifier chip is adopted. By encapsulating RSOA array chips with different center gain wavelengths at the left and right ends of the external cavity, the difference in gain wavelength is used to realize the output of multi-wavelength optical signals. Through the coordinated work of phase shifter array and optical delay line array, flexible output and precise tuning of multi-wavelength optical signals are realized.
It simplifies tuning control and operation complexity, improves response speed and reliability, expands the wavelength coverage of lasers, realizes flexible output and precise tuning of multi-wavelength optical signals, and enhances the flexibility and stability of the system.
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Figure CN121546429A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of external cavity lasers, and more particularly to a multi-channel interference multiplexing external cavity laser chip. BACKGROUND
[0002] With the rapid development of optical communication, coherent detection and laser radar technology, tunable semiconductor lasers have become a hot spot of research and application. The demand for data transmission capacity and beam control complexity in these application fields is constantly increasing, which has driven the demand for multi-wavelength tunable semiconductor lasers. Compared with traditional fixed-wavelength laser arrays, multi-wavelength tunable semiconductor lasers can provide more flexible and complex optical system support while reducing chip control costs, and are therefore considered a future development trend.
[0003] However, existing multi-channel interference lasers use multi-channel reflective semiconductor optical amplifiers (RSOAs), and the lasers usually rely on waveguide delay lines to achieve fixed-wavelength multi-channel output, or through integration of a single channel with a gain chip to achieve limited tuning function. In other words, existing lasers can only achieve single-wavelength dynamic tuning or multi-wavelength fixed output. Such a design shows a lack of flexibility and efficiency in application scenarios that require dense wavelength division multiplexing and precise wavelength tuning.
[0004] The existing external cavity laser scheme needs to perform independent phase modulation on each channel when implementing wavelength selection. This method requires highly precise control technology to ensure accurate phase modulation of each channel, thereby increasing the complexity and cost of system calibration. Since only single-wavelength output can be achieved, its use in application scenarios that require simultaneous multi-wavelength output, such as dense wavelength division multiplexing systems, is limited. At the same time, since the output optical signal needs to be output through the port of the semiconductor optical amplifier, this puts higher requirements on the integrated design of the optical chip, increasing the complexity of manufacturing and packaging. In addition, the implementation of the traditional design has significant limitations. Since the wavelength selection mechanism completely relies on the fixed delay line length in the array waveguide, once the device is manufactured, the wavelength channel configuration is locked and cannot be dynamically tuned. This fixed wavelength configuration results in a lack of flexibility in the structure, especially in application scenarios that require flexible wavelength control, such as dense wavelength division multiplexing systems or reconfigurable optical networks. Therefore, conventional multi-wavelength lasers expose fundamental design defects when meeting the high requirements of modern optical communication and sensing technology for wavelength flexibility.
[0005] Therefore, a laser structure capable of flexibly implementing multi-wavelength tuning of an external cavity laser has become a technical problem to be solved in the current laser field. SUMMARY
[0006] In view of the problems in the background art, the present application provides a multi-channel interference multiplexing type external cavity laser chip, which solves the defects of the prior art external cavity laser.
[0007] The technical solutions of the present application for solving the above technical problems are as follows: A multi-channel interference multiplexing type external cavity laser chip, comprising: a first reflective semiconductor optical amplifier array, a second reflective semiconductor optical amplifier array, and an external cavity; The external cavity comprises a first optical reflector, an optical switch, a free spectral transmission region, a phase shifter array, an optical delay line array, and a second optical reflector connected in sequence; the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array are optically coupled to the input end of the free spectral transmission region of the external cavity; When an injection current is applied, the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array generate gain light, the emitted light enters the free spectral transmission region and is split into each channel of the phase shifter array, and then enters each channel of the optical delay line array; the phase shifter array and the optical delay line array independently modulate the optical signals of each channel, and the modulated optical signals are reflected by the second optical reflector; the reflected optical signals pass through the optical delay line array and the phase shifter array in sequence, and are combined in the free spectral transmission region; the combined light passes through the optical switch and reaches the first optical reflector, and after total reflection by the first optical reflector, the reflected light enters the optical switch, the optical switch divides the reflected light into two parts, one part of the light is routed to the corresponding first reflective semiconductor optical amplifier array and second reflective semiconductor optical amplifier array again through the free spectral transmission region, forming laser oscillation; and the other part of the light is output to an external system through the optical switch; Wherein, the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array have different center gain wavelengths.
[0008] Preferably, the center gain wavelength of the first reflective semiconductor optical amplifier array is and the center gain wavelength of the second reflective semiconductor optical amplifier array is respectively: , , Wherein, is the reference peak wavelength when no voltage is applied to the external cavity, n is the refractive index of the phase shifter array, is the phase shifter array adjustment amount required when matching the first reflective semiconductor optical amplifier array, m is the longitudinal mode order of the external cavity, n is the order difference between the reflection peak corresponding to the center gain wavelength of the first reflective semiconductor optical amplifier array and the reference peak, n' is the order difference between the reflection peak corresponding to the center gain wavelength of the second reflective semiconductor optical amplifier array and the reference peak, FSR F is the free spectral range of the external cavity, .
[0009] The beneficial effects of the present application are: (1) By encapsulating the RSOA array chips with different center gain wavelengths at the left end and the right end of the external cavity respectively, the tuning control and operation complexity are simplified, the response speed and reliability are improved; a single external cavity is used to realize wavelength multiplexing and tuning, thereby improving the integration of the external cavity laser; the center gain wavelengths of the two groups of RSOA arrays are different, and the difference in gain wavelength is utilized to ensure the formation of multi-wavelength optical signal output under two wavelength bands, thereby expanding the wavelength coverage range and application scenarios of the laser; (2) The multi-channel interference multiplexing external cavity laser chip integrates two groups of multi-channel reflective semiconductor optical amplifier arrays, a free spectral transmission zone, a phase shifter array, an optical delay line array, an optical switch, two optical reflectors and other key components. These components work cooperatively to realize flexible output and accurate tuning of multi-wavelength optical signals; (3) When no calibration voltage is applied to the phase shifter array, the external cavity reflection peaks appear at equal periods in the spectral range; the center gain wavelength of each RSOA array chip is overlapped with the reflection peak of the external cavity laser, thereby realizing multi-wavelength excitation; the reflection period of the external cavity is aligned with the center wavelength of different RSOA chips, thereby realizing wavelength tuning of the external cavity laser with super large bandwidth; after the voltage is applied to the phase shifter, the reflection peak will move towards the long wavelength direction or the short wavelength direction, and the shift of the center wavelength will excite the corresponding target wavelength longitudinal mode, thereby realizing flexible tuning of the wavelength of the external cavity laser; (4) The RSOA array chips corresponding to the required wavelength are gated and powered on, while the RSOA array chips that are not powered on cannot provide gain and cannot lase the longitudinal mode, thereby realizing selective output, avoiding multi-longitudinal mode lasing, improving the single mode stability and side mode suppression ratio, reducing the multi-mode competition, and increasing the flexibility and stability of the system; (5) The formula ensures that the center gain wavelength of the working RSOA array chip is strictly matched with the adjusted reflection peak, thereby accurately regulating the wavelength tuning, avoiding mode jumping caused by wavelength mismatch, and improving the stability of the laser output. BRIEF DESCRIPTION OF DRAWINGS
[0010] For easier understanding of the present application, the present application will be described in more detail by referring to the specific embodiments shown in the drawings. These drawings only depict typical embodiments of the present application and should not be considered limiting of the scope of the present application.
[0011] Figure 1 is a structural schematic diagram of a multi-channel interference multiplexing external cavity laser chip provided by an embodiment of the present application. Figure 2 is an external cavity chip reflection spectrum and RSOA gain spectrum adjustment schematic diagram provided by an embodiment of the present application.
[0012] Reference signs: 100-external cavity, 101-first optical reflector, 102-optical switch, 103-free spectral transmission region, 104-phase shifter array, 105-optical delay line array, 106-second optical reflector, 201-first reflective semiconductor optical amplifier array, 202-second reflective semiconductor optical amplifier array. DETAILED DESCRIPTION
[0013] Embodiments of the present application are described below with reference to the accompanying drawings so that those skilled in the art can better understand the present application and implement it, but the listed embodiments are not considered limiting of the present application, and the embodiments described below and technical features in the embodiments can be combined with each other without conflict, wherein the same components are denoted by the same reference signs. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0014] The present application proposes a multi-channel interference multiplexing external cavity laser chip. Please refer to Figure 1 , Figure 1 is a structural schematic diagram of a multi-channel interference multiplexing external cavity laser chip provided by an embodiment of the present application.
[0015] Referring to Figure 1 , in an embodiment of the present application, the multi-channel interference multiplexing external cavity laser chip comprises: an external cavity 100, a first reflective semiconductor optical amplifier array 201 and a second reflective semiconductor optical amplifier array 202; the external cavity comprises a first optical reflector 101, an optical switch 102, a free spectral transmission region 103, a phase shifter array 104, an optical delay line array 105, and a second optical reflector 106. The light source is excited by the first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202, which generate gain light when injected with current. The emitted light enters the free spectral region 103 and is split to each channel of the phase shifter array 104, and then enters the corresponding channel of the optical delay line array 105. The phase shifter array and the optical delay line array independently modulate the light signal of each channel, and the modulated light signal is reflected by the second optical reflector 106. The reflected light signal passes through the optical delay line array 105 and the phase shifter array 104 in turn, and is combined in the free spectral region 103. The combined light passes through the optical switch 102 to the first optical reflector 101, and is totally reflected by the first optical reflector 101 to enter the optical switch 102 as reflected light. The optical switch 102 divides the reflected light into two parts, one of which is routed to the corresponding first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202 again through the free spectral region 103, forming a laser oscillation; the other part of the light is output to an external system through the optical switch 102.
[0016] The optical switch 102 can be an MZI optical switch, including 2 input waveguides, a 3dB beam splitter, 2 interference arms, a 3dB combiner and 2 output waveguides. In terms of function, by controlling the phase of one interference arm, the interference state (constructive or destructive) of the two reflected lights at the combining point after total reflection by the first optical reflector 101 is changed, so as to guide the optical energy to the external output port and the free spectral region, realizing the switching function of the optical path; by accurately controlling the phase, any splitting ratio can be realized.
[0017] The free spectral region 103 acts as a beam splitter for its input end and as a combiner for its output end. Its principle is based on the diffraction and focusing of light: when a beam of light of a certain wavelength enters the free spectral region from a certain input waveguide in the middle, the light will diffuse freely like a point source after entering the wide flat waveguide region from the narrow input waveguide, forming a divergent spherical wave front. This process is equivalent to distributing the power of the input light signal to all array waveguides, realizing beam splitting. For the array waveguides, different wavelengths of light that have passed through the array waveguides and introduced a large phase difference need to be recombined into different output waveguides. This process is the inverse of beam splitting, but the principle is the same. Due to the length difference design of the array waveguides, for a certain wavelength, when these lights reach the free spectral region where the output waveguide array is located, their optical path difference is exactly an integer multiple of the wavelength. Therefore, they add up in phase at a certain output waveguide position (for example, the middle waveguide), constructive interference occurs, and the optical energy is coupled into that waveguide efficiently, realizing beam combining.
[0018] The multi-channel interference multiplexing external cavity laser chip integrates two sets of multi-channel reflective semiconductor optical amplifier arrays, a free spectral transmission region 103, a phase shifter array 104, an optical delay line array 105, an optical switch 102, two optical reflectors, and other key components. The number of channels of the phase shifter array 104 is consistent with and corresponds to the number of channels of the optical delay line array 105. These components work together to achieve flexible output and precise tuning of multi-wavelength optical signals.
[0019] The external cavity laser includes multiple sets of multi-channel RSOA array chips Figure 1 In the middle, the first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202 are two sets of RSOA arrays as an illustration), the center gain wavelengths of the two sets of RSOA array chips are different. This design takes advantage of the difference in gain wavelength to ensure the formation of multi-wavelength optical signal output in two wavelength bands, thereby expanding the wavelength coverage range and application scenarios of the laser.
[0020] When the first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202 are activated at the same time, the optical delay line array 105 filters out the corresponding wavelength according to the input signal. By applying a control signal to the phase shifter array 104, the phase characteristics of the waveguide are adjusted to achieve redshift or blueshift of the lasing wavelength.
[0021] The two optical reflectors and the end faces of the two sets of RSOA array chips together form an optical resonant cavity. Through the high reflectivity of the optical reflectors and the partial reflection characteristics of the RSOA end faces, the light beam oscillates back and forth in the cavity and is amplified, and finally realizes the longitudinal mode lasing of laser at the selected wavelength.
[0022] Figure 2 It is an external cavity chip reflection spectrum and RSOA gain spectrum adjustment schematic provided by the embodiment of the application, referring to Figure 2 The external cavity 100 includes an optical delay line array 105 composed of a waveguide cascade structure with an equal difference sequence. When no calibration voltage is applied, the external cavity reflection peaks will appear at equal intervals in the spectral range; after applying a voltage to the phase shifter array 104, these reflection peaks will consistently redshift or blueshift. At the left and right ends of the external cavity, RSOA array chips with different center gain wavelengths are packaged, and the center gain wavelength of each chip overlaps with the reflection peak of the external cavity laser.
[0023] When the adjacent two reflection peaks overlap with the center gain wavelengths of the first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202, dual-wavelength excitation can be achieved.
[0024] In addition, after applying the calibration voltage, the reflection peaks will move towards the long wavelength direction or the short wavelength direction, and the shift of the center wavelength will cause the longitudinal mode excitation of the corresponding target wavelength, and finally realize the tuning of the laser wavelength.
[0025] In another embodiment of the present application, the first reflective semiconductor optical amplifier array 201 or the second reflective semiconductor optical amplifier array 202 can be selectively excited, and the RSOA array chip corresponding to the required wavelength is powered on alone, and tuning is achieved by adjusting the phase shifter array 104. The RSOA array chip that is not powered on cannot provide gain, so it cannot lase the longitudinal mode; the reflection coefficient can be expressed as: , where N is the number of phase shifters in the external cavity, is the wavelength range of the laser tuning region, j is the imaginary unit, i is a positive integer, r3 is the reflection coefficient of the first optical reflector 101, β is the complex propagation constant, Lp is the length of the phase shifter array 104, Lm is the propagation length in the free spectral transmission region 103, and Li is the length of the i-th optical delay line in the optical delay line array 105. Only the optical signal that meets the interference condition will interfere to form a resonance at the connection of the optical switch 102.
[0026] In yet another embodiment of the present application, the center gain wavelength of the first reflective semiconductor optical amplifier array 201 and the center gain wavelength of the second reflective semiconductor optical amplifier array 202 are respectively: , , where, is the reference peak wavelength when no voltage is applied to the external cavity, n is the refractive index of the phase shifter array, is the amount of phase shifter array adjustment required to match the first reflective semiconductor optical amplifier array 201, is the amount of phase shifter array adjustment required to match the second reflective semiconductor optical amplifier array 202, m is the longitudinal mode order of the external cavity, is the order difference between the reflection peak corresponding to the center gain wavelength of the first reflective semiconductor optical amplifier array 201 and the reference peak, is the order difference between the reflection peak corresponding to the center gain wavelength of the second reflective semiconductor optical amplifier array 202 and the reference peak, the first reflective semiconductor optical amplifier array 201 and the second reflective semiconductor optical amplifier array 202 have different center gain wavelengths, so after applying a voltage, they correspond to different reflection peaks, , FSR is the free spectral range of the external cavity.
[0027] This invention improves the integration of external cavity lasers by encapsulating RSOA array chips with different center gain wavelengths at the left and right ends of the external cavity, respectively, and using a single external cavity to achieve wavelength multiplexing and tuning. The two RSOA arrays have different center gain wavelengths, and by utilizing this difference, multi-wavelength optical signal output is ensured in two bands, thereby expanding the laser's wavelength coverage and application scenarios. When no calibration voltage is applied to the phase shifter, the external cavity reflection peaks appear periodically within the spectral range. Multi-wavelength excitation is achieved by utilizing the overlap between the center gain wavelength of each RSOA chip and the reflection peak of the external cavity laser. By aligning the external cavity's reflection period with the center wavelengths of different RSOA chips, ultra-wide bandwidth wavelength tuning of the external cavity laser is achieved. After applying voltage to the phase shifter, the reflection peaks shift towards longer or shorter wavelengths; the shift in center wavelength causes longitudinal mode excitation of the corresponding target wavelength, enabling flexible wavelength tuning of the external cavity laser. By powering on the RSOA chip corresponding to the desired wavelength, while an unpowered RSOA chip cannot provide gain and therefore cannot emit longitudinal modes, selective output is achieved, avoiding multi-mode lasing and increasing the system's flexibility and stability. A formula ensures that the center gain wavelength of the operating RSOA chip is strictly matched with the adjusted reflection peak, precisely controlling wavelength tuning and avoiding mode jumps caused by wavelength mismatch, thus improving the stability of the laser output.
[0028] The various embodiments in this invention are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.
[0029] The embodiments described above are merely preferred embodiments of the present invention. The terms "in one embodiment," "in another embodiment," "in yet another embodiment," or "in still another embodiment" used in this specification all refer to one or more of the same or different embodiments according to this disclosure. Ordinary variations and substitutions made by those skilled in the art within the scope of the present invention should be included within the protection scope of the present invention.
Claims
1. A multi-channel interference multiplexed external cavity laser chip, characterized by, Comprising: a first reflective semiconductor optical amplifier array, a second reflective semiconductor optical amplifier array, and an external cavity; the external cavity comprises a first optical reflector, an optical switch, a free spectral range, a phase shifter array, an optical delay line array and a second optical reflector connected in sequence; the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array are optically coupled to the input end of the free spectral range of the external cavity; the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array generate gain light when injected with current, the emitted light enters the free spectral range and is split to each channel of the phase shifter array, and then enters each channel of the optical delay line array; the phase shifter array and the optical delay line array independently modulate the optical signals of each channel, and the modulated optical signals are reflected by the second optical reflector; the reflected optical signals pass through the optical delay line array and the phase shifter array in sequence, and are combined in the free spectral range; the combined light passes through the optical switch and reaches the first optical reflector, and after total reflection by the first optical reflector, the reflected light enters the optical switch as reflected light; the optical switch divides the reflected light into two parts, one part of the light is routed to the corresponding first reflective semiconductor optical amplifier array and second reflective semiconductor optical amplifier array again through the free spectral range, forming laser oscillation; and the other part of the light is output to an external system through the optical switch; wherein the first reflective semiconductor optical amplifier array and the second reflective semiconductor optical amplifier array have different central gain wavelengths.
2. The multi-channel interference multiplexing external cavity laser chip according to claim 1, characterized in that, a center gain wavelength of the first reflective semiconductor optical amplifier array a center gain wavelength of the second reflective semiconductor optical amplifier array respectively: ， ， wherein, is the reference peak wavelength when no voltage is applied to the external cavity, n is the refractive index of the phase shifter array, is the phase shifter array adjustment amount required to match the first reflective semiconductor optical amplifier array, is the phase shifter array adjustment amount required to match the second reflective semiconductor optical amplifier array, m is the longitudinal mode order of the external cavity, is the order difference between the reflection peak corresponding to the center gain wavelength of the first reflective semiconductor optical amplifier array and the reference peak, is the order difference between the reflection peak corresponding to the center gain wavelength of the second reflective semiconductor optical amplifier array and the reference peak, FSR is the free spectral range of the external cavity, .