An ultra-wideband laser array and tunable laser
By fabricating subarrays with different gain ranges on the same wafer and combining docking growth and reconstructed equivalent chirp techniques, the problem of limited wavelength tuning range of existing laser arrays has been solved, realizing an ultra-wideband, highly integrated, low-cost, and highly stable tunable laser.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-31
AI Technical Summary
Existing discrete laser arrays and distributed feedback lasers have limited wavelength tuning ranges, making it difficult to achieve wide-range spectral coverage. They also suffer from low integration, high cost, and poor wavelength stability. External coupling structures increase device size and introduce coupling losses.
Subarrays with different gain ranges are fabricated on the same wafer using monolithic integration technology. Grating layers are prepared by combining docking growth and reconstructed equivalent chirp technology. The laser array and coupler are monolithically integrated by photonic wire bonding. Wavelength tuning is performed using MEMS micromirrors.
It realizes an ultra-wideband, highly integrated, low-cost and highly stable tunable laser, which expands the wavelength tuning range, reduces optical signal coupling loss and avoids wavelength crosstalk.
Smart Images
Figure CN122495166A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor laser technology, and in particular to an ultra-wideband laser array and a tunable laser. Background Technology
[0002] With the development of 5G communication, data center interconnection and long-distance trunk communication, dense wavelength division multiplexing (DWDM) technology has placed higher demands on light sources, especially in terms of ultra-wide bandwidth coverage, multi-wavelength integration and dynamic wavelength tuning.
[0003] Existing discrete laser arrays, limited by the bandwidth of a single gain region, struggle to achieve wide-range spectral coverage. Distributed feedback (DFB) lasers are also limited by the energy level structure of a single gain material, preventing broad-range wavelength tuning. While combining multiple independent light source devices can extend the wavelength range to some extent, it suffers from low integration density, high cost, and poor wavelength stability, failing to meet the demands of high-performance optical communication systems. Furthermore, external coupling structures during laser integration not only increase device size but also introduce additional coupling losses.
[0004] Therefore, how to realize a laser array with superimposed bandwidth of multiple gain regions through monolithic integration technology, and combine it with coupling structure to obtain an ultra-wideband, highly integrated, low-cost, and highly stable laser array and tunable laser, is a problem that urgently needs to be solved. Summary of the Invention
[0005] Purpose of the invention: The first purpose of this invention is to provide an ultra-wideband laser array, and the second purpose is to obtain an ultra-wideband, highly integrated, low-cost, and highly stable tunable laser based on the ultra-wideband laser array.
[0006] Technical solution: To achieve the above objectives, the present invention provides an ultra-wideband laser array, which is fabricated on the same wafer with sub-arrays having different gain ranges. Each sub-array includes multiple laser units. A single laser unit includes, from bottom to top, a substrate, a buffer layer, a multi-quantum well structure layer, and a grating layer (4). The thickness and composition of the multi-quantum well structure layer are different between the sub-arrays. The laser units in the sub-array are arranged side by side along the light emission direction, and the grating layer structure period is different between the laser units in a single sub-array.
[0007] Preferably, a subarray with different gain ranges is fabricated on the same wafer using a docking growth technique, the method being as follows:
[0008] S1. Prepare alignment mark patterns on the substrate;
[0009] S2. Based on the alignment mark pattern, a buffer layer, a first type of multi-quantum-well structure layer Q1, and a grating layer G1 are sequentially epitaxially grown on the substrate to form a first subarray including multiple laser units.
[0010] S3. Simultaneously etch away a portion of the first type of multi-quantum well structure layer Q1 and grating layer G1 in the first sub-array along the vertical direction of the laser output end face. Epitaxially grow a second type of multi-quantum well structure layer Q2 and grating layer G2 in the etched area to form a second sub-array. Repeat this process until N sub-arrays are grown in parallel in different regions of the substrate, forming N-1 docking growth interfaces. The multi-quantum well structure layer is an InGaAsP compound or an InGaAlAs compound material.
[0011] S4. Fabricate the outgoing waveguide of each laser unit in the subarray in a direction parallel to the docking growth interface.
[0012] Preferably, the grating layer is prepared using reconstruction-equivalent chirp (REC) technology. The preparation method is as follows: an unexposed photoresist is covered on the epitaxial wafer of the substrate, a uniform grating is prepared on the photoresist by holographic exposure, a periodically changing sampling grating pattern is superimposed on the uniform grating by a one-step exposure method using a sampling grating photomask, and the grating layer is prepared by development.
[0013] Preferably, the grating layer is prepared using REC technology. The preparation method is as follows: an unexposed photoresist is covered on the epitaxial wafer of the substrate, a uniform grating is prepared on the photoresist by holographic exposure, a periodically changing sampling grating pattern is superimposed on the uniform grating by a one-step exposure method using a sampling grating photomask, and the grating layer is prepared by development.
[0014] The present invention discloses a tunable laser, comprising a laser array and a coupler, wherein the output waveguide of the laser array and the input waveguide of the coupler are connected.
[0015] Preferably, the laser array output waveguide is connected to the input waveguide of the coupler through a docking growth technique. Specifically, a portion of the multi-quantum well structure layer is etched away in a direction perpendicular to the grating, and a passive layer is epitaxially grown. An array waveguide grating, a multimode interference coupler, or a star coupler chip is fabricated on the passive layer to connect the input waveguide of the coupler to the laser array output waveguide.
[0016] Preferably, the laser array output waveguide is connected to the coupler input waveguide via photonic leads. Specifically, the trajectory of the photonic lead waveguide between the laser array and the coupler is simulated and calculated based on the port size, position, material, and spacing parameters of the laser array and the coupler to obtain the optimal photonic lead bonding. Photonic leads are then fabricated using two-photon exposure technology as coupling waveguides to connect the coupler input waveguide to the laser array output waveguide.
[0017] Preferably, the coupler is an N×1 silicon photonic integrated array switch, where N is the number of arrays of the laser array and the number of input ports of the coupler. After passing through the coupler, the laser is output from a single waveguide from the tunable laser. When a single laser unit in the laser array is lased, the laser lased by the single laser unit is output from the output waveguide by tuning the individual Mach-Zehnder Interferometer (MZI) array switches in the silicon photonic integrated array switch.
[0018] Preferably, the coupler is an N×1 silicon photonic integrated electro-optic or thermo-optic MZI array switch, where N is the number of input waveguides of the coupler. After passing through the coupler, the laser is output from a single waveguide from the tunable laser. When a single laser unit in the laser array is lased, the individual sub-MZI array switches in the coupler are tuned through the electro-optic or thermo-optic effect, so that the laser lased by the single laser unit is output from the output waveguide.
[0019] Preferably, the coupler includes a first lens group, a second lens group, a MEMS rotating mirror, and an output optical fiber. The laser array's light output direction is located at the focal plane of the first lens group, converting the laser beam into parallel light to illuminate the MEMS micromirror for wavelength selection and beam redirection, and then coupling it into the output optical fiber through the second lens group.
[0020] Beneficial Effects: This invention has the following advantages: 1. By using docking growth technology to grow different gain materials in different regions of the same substrate, the bandwidth of each region is superimposed to achieve ultra-wideband spectral coverage, thereby expanding the wavelength tuning bandwidth of the laser array and its laser; 2. By using REC technology to prepare the grating layer, the fabrication cost of the laser array and its laser is reduced, while also improving the accuracy of the wavelength; 3. During the laser integration process, the coupler and laser array chip are monolithically integrated using docking growth technology or photonic wire bonding (PWB) technology, effectively reducing optical signal coupling loss; 4. During the laser integration process, wavelength tuning is performed using MEMS micromirrors, effectively reducing optical signal coupling loss, while avoiding wavelength crosstalk problems that may be caused by monolithically integrated couplers, which is beneficial to improving the stability of the tunable laser. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the docking growth process;
[0022] Figure 2 Schematic diagram of the sampling grating fabricated for REC;
[0023] Figure 3 A schematic diagram of the process for growing a passive coupler.
[0024] Figure 4 A schematic diagram of a passive coupler integrating different materials for PWB technology;
[0025] Figure 5 This is a schematic diagram of a tunable laser based on a silicon photonic integrated switch coupler;
[0026] Figure 6 Here is a schematic diagram of a tunable laser structure based on MEMS-driven micromirrors.
[0027] In this diagram, 1 is the substrate, 2 is the buffer layer, 3 is the quantum well structure, 4 is the grating layer, 5 is the docking growth interface, 6 is the output waveguide of the laser unit, 7 is the laser unit electrode, 8 is the uniform grating, 9 is the sampling grating, 10 is the InP-based passive coupler, 11 is the photonic lead fabricated by PWB technology, 12 is the coupler of other material systems, 13 is the output waveguide, 14 is the silicon photonics switch unit, 15 is the silicon photonics integrated switch coupler chip, 16 is the first lens group, 17 is the MEMS rotating mirror, 18 is the second lens group, and 19 is the output fiber. Detailed Implementation
[0028] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.
[0029] The resonant cavity of the laser array described in this invention is a distributed feedback structure. Using a docking growth technique, subarrays with different gain ranges are grown on the same wafer. Each subarray includes N groups of laser units. A single laser unit, from bottom to top, comprises: a substrate 1, a buffer layer 2, a multi-quantum-well structure layer 3, and a grating layer 4.
[0030] Among them, the thickness and composition of the multi-quantum well structure layer 3 between the sub-arrays are different, the laser units in the sub-arrays are arranged in parallel along the light output direction to form multiple docking growth interfaces 5, and the grating layer 4 structure period is different between the laser units in the sub-arrays.
[0031] like Figure 1 As shown, the process of growing subarrays with different gain ranges on the same wafer based on docking growth technology is as follows:
[0032] S1. Prepare alignment mark patterns on substrate 1 with a depth of 0.5~1.5μm; the preparation methods for alignment mark patterns include contact photolithography, wet etching, or dry etching.
[0033] S2. Based on the alignment mark pattern, a buffer layer, a first type of multi-quantum well structure layer Q1, and a grating layer 4G1 are epitaxially grown sequentially on the substrate 1; wherein the fluorescence spectrum peak wavelength of the grating layer 4G1 is at least 60 nm shorter than the fluorescence spectrum peak wavelength of the multi-quantum well structure layer Q1, forming a first sub-array including multiple laser units.
[0034] S3. Simultaneously etch away a portion of the first type of multi-quantum well structure layer Q1 and grating layer 4G1 in the first sub-array along the vertical direction of the laser output end face. Then, grow the second type of multi-quantum well structure layer Q2 and grating layer 4G2 epitaxially in the etched area to form the second sub-array. Repeat this process until N sub-arrays are grown in parallel in different regions of the substrate 1.
[0035] S4. In a direction parallel to the subarray growth interface 5, prepare the outgoing waveguide 6 of each laser unit in the subarray.
[0036] The output waveguide 6 is designed to have its light output direction parallel to the subarray growth interface 5. This design can eliminate the adverse effects of the interfaces formed during the growth of different subarrays on the laser performance. The total bandwidth of the laser array is the sum of the bandwidths of the gain regions of different subarrays.
[0037] In the aforementioned ultra-wideband laser array structure, this invention utilizes the Reconstructed Equivalent Chirp (REC) technique to fabricate the grating layer 4, thereby reducing the fabrication cost of the Bragg grating and simultaneously improving the wavelength accuracy of the laser. The fabrication principle is as follows: various equivalent complex grating structures, including phase shift and chirp, are achieved by designing a sampling grating 9. The refractive index change of the sampling grating 9 along the cavity length direction is expressed as:
[0038] (1)
[0039] in For sampling function, For a uniform grating with 8 periods, j is the imaginary unit.
[0040] Expressed via Fourier transform:
[0041] (2)
[0042] Where P represents the 9-period sampling grating. The m-th order Fourier expansion coefficients of the sampling grating 9.
[0043] According to formulas (1) and (2), the refractive index change of the sampling grating 9 along the cavity length direction is expressed as:
[0044] (3)
[0045] As can be seen from formula (3), the sampling grating 9 is actually a superposition of sub-gratings of different orders and periods, where the grating period of the m-th order sampling grating 9 is:
[0046] (4)
[0047] Typically, a +1 order sub-grating is used as the laser resonator. The Bragg wavelength of the uniform grating 8 is designed to be far from the gain region to avoid laser lasing, while the Bragg wavelength of the +1 order sub-grating is located at the center of the gain region. By using the same uniform grating 8 and changing the period of its sampling grating 9, different laser wavelengths can be achieved. Furthermore, as can be seen from Equation (4), the period of the sampling grating 9 is on the order of μm, which can be achieved through micron-level photolithography. In addition, taking the derivative of both sides of Equation (4), it can be seen that the process tolerance of its sampling grating 9 is improved by two orders of magnitude compared to the uniform grating 8 fabricated by EBL.
[0048] This invention achieves the effect of a traditional phase-shifting grating by using REC technology to prepare a uniform grating 8 with only one holographic exposure and a sampling grating 9 with one micron-level photolithography step, thereby improving the wavelength accuracy of the subarray and replacing the high-cost electron beam etching technology.
[0049] like Figure 2 As shown, the process of holographic exposure to prepare a uniform grating 8 and a single micrometer-level photolithography to prepare a sampling grating 9 is as follows: Unexposed photoresist is covered on the epitaxial wafer, and holographic exposure is performed to prepare a uniform grating 8 pattern with a specific period on the photoresist. After holographic exposure, a sampling grating photomask is used to superimpose a periodically varying sampling grating 9 pattern onto the uniform grating 8 using a one-step exposure method. After two exposures, the sampling grating 9 pattern is displayed on the photoresist through development, thus completing the fabrication process of the grating layer 4. Using photoresist as a mask, the sampling grating pattern can be transferred from the photoresist to the primary epitaxial wafer through wet or dry etching.
[0050] After forming the sampling grating grooves in the laser array through an etching process, InP of a specific thickness is epitaxially grown to fill the surface of the sampling grating grooves, with the sampling grating orientation perpendicular to the laser output end face. Subsequently, an InGaAsP etching barrier layer is grown for etching at a specific depth during ridge waveguide fabrication, followed by the growth of an InP capping layer and an InGaAs ohmic contact layer. Finally, electrode 7 is fabricated, completing the laser array fabrication.
[0051] Taking a wavelength of 1550nm as an example, the period of a uniform grating 8 is typically around 256nm, while the period of a first-order sampling grating 9 is 3~4μm. Therefore, it can be fabricated using micrometer-scale photolithography, and its influence on the lasing wavelength is increased by two orders of magnitude compared to lasers fabricated with a uniform grating 8-period grating. Therefore, fabricating the grating layer 4 using REC technology can reduce the fabrication cost of the laser array and improve the accuracy of the wavelength.
[0052] The tunable laser of this invention includes the aforementioned ultra-wideband laser array and a coupler. The coupler is an arrayed waveguide grating (AWG), a multimode interference (MMI), a star coupler, a coupler based on a MEMS-driven mirror group, or a coupler based on a silicon photonic switch. When the coupler is an AWG / MMI / star coupler, by growing a waveguide grating or a star coupler chip on the laser array and connecting the input waveguide of the AWG / MMI / star coupler to the end face of the output waveguide of the laser array, an active-passive waveguide mode structure is formed. This enables monolithic integration of the passive coupler 10 and the laser array chip, allowing the laser array to achieve combined output through coupling with the AWG / MMI / star coupler, effectively reducing optical signal coupling loss. The AWG has only one waveguide output, while the MMI / star coupler has one or more waveguides outputting simultaneously. The AWG / MMI / star coupler chip is made of silicon nitride, silicon dioxide, or InP-based material.
[0053] This invention enables the growth of InP-based material couplers alongside a laser array using a docking growth technique, thereby achieving laser array multiplexing output. Figure 3 As shown, the fabrication process is as follows: Based on the aforementioned ultra-wideband laser array, along the direction of the outgoing waveguide 6, a portion of the material is completely removed using an etching process to expose the substrate 1. A passive layer is selectively epitaxially grown on the original waveguide layer in the removed area. Couplers (AWG / MMI / star couplers) are then re-etched in the passive layer region, achieving efficient optical connection between the active and passive coupler regions, thereby forming a passive coupling structure for passive optical signal transmission. This method allows for flexible and independent design of the material properties of the active and passive regions to meet different functional requirements.
[0054] Taking the coupler and laser as being made of the same material and both fabricated on an InP-based material platform as an example, an InGaAsP or InAlGaAs material structure containing quantum wells is deposited on substrate 1. Then, an etching process is used to completely remove the quantum well material, which serves as the coupler region, exposing substrate 1. In the removed region, an InP or InGaAsP waveguide layer is redeposited using a secondary epitaxial growth technique to form the coupler region structure.
[0055] like Figure 4 As shown, a laser array can be connected to a coupler made of silicon nitride or silicon dioxide using photonic wire bonding (PWB) technology. The output waveguide of the laser array is connected to the input waveguide of the coupler. The photonic wire bonding fabrication process involves mounting the laser array and coupler 12 onto a metal substrate, aligning the output waveguide 6 of the array with the input waveguide of the coupler and maintaining a gap of approximately 250 μm between them. Based on parameters such as the gap, the size and material of the laser array's output waveguide 6, and the size and material of the coupler, the physical characteristics and compatibility of PWB technology in hybrid chip integration applications using different material systems are studied. Specifically, the trajectory of the photonic wire waveguide between the laser array and the coupler is simulated and calculated based on the port size, position, material, and gap of the laser array and coupler to obtain the optimal photonic wire trajectory. A photonic wire 11 conforming to the optimized trajectory is fabricated using two-photon exposure technology as a coupling waveguide to reduce coupling loss and complete the integration of the laser array and coupler. Figure 13 shows the integrated output waveguide. The coupling structure can be fabricated on material systems such as Si-based, SOI, silicon nitride, and lithium niobate.
[0056] like Figure 5 As shown, a laser array can be connected to a silicon optical switch coupler using photolithography (PWB) technology. The output waveguide of the laser array is connected to the input waveguide of the coupler. The PWB fabrication process involves mounting the laser array and coupler 15 onto a metal substrate, aligning the output waveguide 6 of the array with the input waveguide of the coupler and maintaining a gap of approximately 250 μm between them. Based on parameters such as the gap, the size and material of the laser array's output waveguide 6, and the size and material of the coupler, the physical characteristics and compatibility of PWB technology in hybrid chip integration applications using different material systems are investigated. Specifically, the trajectory of the photonic lead waveguide between the laser array and the coupler is simulated and calculated based on the port size, position, material, and gap of the laser array and coupler to obtain the optimal photonic lead trajectory. A photonic lead 11 conforming to the optimized trajectory is fabricated using two-photon exposure technology as a coupling waveguide to reduce coupling loss and complete the integration of the laser array and the silicon optical switch coupler.
[0057] The coupler based on the MEMS-driven mirror assembly includes lens group one 16, lens group two 18, MEMS rotating mirror 17, and output fiber 19. The laser array's output direction is placed on the focal plane of lens group one 16, thereby converting the laser into parallel light that illuminates the MEMS rotating mirror 17. By changing the rotation angle of the MEMS rotating mirror 17, the laser beam is redirected and coupled into the output fiber 19 through lens group two 18. It is worth noting that the laser using the MEMS-driven mirror assembly can only output one wavelength at a time. Compared to AWG and MMI coupling schemes, this tuning method reduces coupling loss, avoids wavelength sensitivity, and prevents wavelength crosstalk that may occur when multiple wavelengths are in the coupler. This improves the stability of the tunable laser. Through MEMS dynamic tuning, wavelengths in the laser array are selected one by one, achieving ultra-bandwidth tuning.
[0058] Taking 64 laser units and a channel spacing of 127μm as an example, such as Figure 6 As shown, the uppermost laser unit is offset by 4064 μm relative to the optical axis of the focusing lens group, therefore the selected focusing lens group size needs to be greater than 10 mm. To ensure the coupling efficiency of the single-mode fiber, a long-focal-length lens group should be selected to ensure that its numerical aperture is smaller than the numerical aperture of the fiber. Based on the above lens group size and the NA value of the single-mode fiber, the focal length of the lens group needs to be greater than 25 mm. Simultaneously, to ensure that all light rays can be deflected by the MEMS, the MEMS size needs to be greater than 25 mm. After selecting suitable lens groups and MEMS sizes, they are encapsulated together in a sealed housing and output through output fiber 19, forming a wide-range tunable laser.
Claims
1. An ultra-wideband laser array, comprising: Subarrays with different gain ranges are fabricated on the same wafer. Each subarray includes multiple laser units. A single laser unit includes a substrate (1), a buffer layer (2), a multi-quantum well structure layer (3), and a grating layer (4) from bottom to top. The thickness and composition of the multi-quantum well structure layer (3) are different between subarrays. The laser units in the subarray are arranged side by side along the light output direction, and the grating layer (4) structure period is different between the laser units in each subarray.
2. The ultra-wideband laser array of claim 1, wherein, Subarrays with different gain ranges are fabricated on the same wafer using docking growth technology. The method is as follows: S1. Prepare alignment mark patterns on substrate (1); S2. Based on the alignment mark pattern, a buffer layer, a first type of multi-quantum well structure layer Q1 and a grating layer (4) G1 are epitaxially grown sequentially on the substrate (1) to form a first subarray including multiple laser units. S3. Simultaneously etch away a portion of the first type of multi-quantum well structure layer Q1 and grating layer (4) G1 in the first sub-array along the vertical direction of the laser output end face. Epitaxially grow the second type of multi-quantum well structure layer Q2 and grating layer (4) G2 in the etched area to form the second sub-array. In the same way, N sub-arrays are finally grown in parallel in different areas of the substrate (1) to form N-1 docking growth interfaces (5). The multi-quantum well structure layer (3) is an InGaAsP compound or InGaAlAs compound material. S4. In the direction parallel to the docking growth interface (5), prepare the outgoing waveguide (6) of each laser unit in the subarray.
3. The ultra-wideband laser array of claim 1, wherein, The grating layer (4) is prepared by reconstruction equivalent chirp (REC) technology. The preparation method is as follows: cover the unexposed photoresist on the epitaxial wafer of the substrate (1), prepare a uniform grating (8) on the photoresist by holographic exposure, and use the sampling grating photomask to superimpose the periodically changing sampling grating (9) pattern on the uniform grating (8) by one-step exposure method, and then complete the preparation of the grating layer (4) by development.
4. The ultra-wideband laser array of claim 2, wherein, The grating layer (4) is prepared using REC technology. The preparation method is as follows: Unexposed photoresist is covered on the epitaxial wafer of the substrate (1), and a uniform grating (8) is prepared on the photoresist by holographic exposure. A sampling grating pattern (9) with periodic variation is superimposed on the uniform grating (8) by a one-step exposure method using a sampling grating photomask. The grating layer (4) is then prepared by development.
5. A tunable laser based on the ultrawideband laser array described in claims 1-4, characterized in that, It includes a laser array, a coupler, and the output waveguide of the laser array is connected to the input waveguide of the coupler.
6. The tunable laser according to claim 5, characterized in that, The laser array output waveguide is connected to the input waveguide of the coupler through docking growth technology. Specifically, a part of the multi-quantum well structure layer (3) is etched away in the direction perpendicular to the grating, and a passive layer is epitaxially grown. An array waveguide grating or a multimode interference coupler or a star coupler chip is fabricated on the passive layer to connect the input waveguide of the coupler with the laser array output waveguide.
7. The tunable laser according to claim 5, characterized in that, The laser array output waveguide is connected to the coupler input waveguide via a photonic lead (11). Specifically, the trajectory of the photonic lead waveguide between the laser array and the coupler is simulated and calculated based on the port size, position, material, and spacing parameters of the laser array and the coupler to obtain the optimal photonic lead bonding. The photonic lead (11) is then fabricated using two-photon exposure technology as a coupling waveguide to connect the coupler input waveguide with the laser array output waveguide.
8. The tunable laser according to claim 5, characterized in that, The coupler is an N×1 silicon photonic integrated array switch, where N is the number of arrays of the laser array and the number of input ports of the coupler. After passing through the coupler, the laser is output from a single waveguide from the tunable laser. When a single laser unit in the laser array is lased, the laser lased by the single laser unit is output from the output waveguide by tuning the individual Mach-Zehnder interferometer (MZI) array switches in the silicon photonic integrated array switch.
9. The tunable laser according to claim 5, characterized in that, The coupler is an N×1 silicon photonic integrated electro-optic or thermo-optic MZI array switch, where N is the number of input waveguides of the coupler. After passing through the coupler, the laser is output from a single waveguide from the tunable laser. When a single laser unit in the laser array is lased, the individual sub-MZI array switches in the coupler are tuned through electro-optic or thermo-optic effects, so that the laser lased by the single laser unit is output from the output waveguide.
10. The tunable laser according to claim 5, characterized in that, The coupler includes lens group one (16), lens group two (18), MEMS rotating mirror (17) and output fiber (19). The laser array output direction is located at the focal plane of lens group one (16), converting the laser beam into parallel light to irradiate the MEMS rotating mirror (17) for wavelength selection and beam redirection, and then coupling into the output fiber (19) through lens group two (18).