An ultralens tunable laser, a tuning method and a preparation method

Abstract

The application provides a tunable lens laser, a tuning method and a preparation method. The tunable lens laser comprises a rear-end high-reflection boundary, an optical waveguide, a front-end low-reflection light-out end face and a transparent end cap layer. A double-channel phase tunable superlens and a tuning controller are arranged in the light-out direction of the front-end low-reflection light-out end face. The double-channel phase tunable superlens comprises a main transmission output phase area and a weak feedback phase area located at the periphery of the same plane of the main transmission output phase area. The tuning controller is used for controlling the phase of the weak feedback phase area. The wavelength change is realized by adjusting the phase of the weak feedback phase area during tuning. The preparation method comprises forming the double-channel phase tunable superlens and the tuning controller in the light-out direction of the front-end low-reflection light-out end face. The tuning is realized by adjusting the phase of the weak feedback phase area. The main transmission output phase area and the weak feedback phase area are located in the same plane, the occupied space is small, the external structure is reduced, and the chip-level integration and packaging stability can be improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, and particularly relates to a superlens tunable laser, a tuning method, and a fabrication method. Background Technology

[0002] Traditional InP (Indium Phosphide) tunable lasers primarily rely on structures such as DFB (Distributed Feedback), DBR (Distributed Bragg Reflection), SG-DBR (Sampling Grating Distributed Bragg Reflection), GCSR (Grate Coupled Sampling Reflection), external cavity gratings, etalons, or MEMS (Micro-Electro-Mechanical Systems) mirrors to achieve wavelength selection. While these solutions are mature, they typically require long grating regions, phase regions, and multiple electronically controlled regions arranged along the waveguide, resulting in large layout lengths, complex control matrices, and potential reductions in output efficiency due to absorption in the tuning section, grating loss, and regeneration processes. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a superlens tunable laser, a tuning method and a fabrication method, for solving at least one of the problems of tunable lasers mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides a superlens tunable laser, comprising an edge-emitting laser unit, a front low-reflection emission end face, and a transparent end cap layer arranged sequentially along the optical axis. The edge-emitting laser unit includes an internal optical waveguide and a rear high-reflection boundary located at the end away from the front low-reflection emission end face. The superlens tunable laser further includes a dual-channel phase-tunable superlens and a tuning controller disposed in the emission direction of the front low-reflection emission end face. The dual-channel phase-tunable superlens includes a main transmission output phase region on the optical axis and a weak feedback phase region located on the outer periphery of the same plane as the main transmission output phase region. The tuning controller is used to control the phase of the weak feedback phase region. The transmission efficiency of the main transmission output phase region is >60%, the feedback power of the weak feedback phase region accounts for 0.1%–8% of the output power, the residual reflectivity of the front low-reflection light-emitting end face is less than 1%, and the rear high-reflection boundary, the optical waveguide, the front low-reflection light-emitting end face and the dual-channel phase-tunable superlens together constitute the laser oscillation cavity.

[0005] Furthermore, the laser oscillation cavity satisfies the oscillation condition 2β(λ)L + φHR(λ) + φR(λ,V,T) = 2πm, where β(λ) is the propagation constant of the optical waveguide, L is the equivalent cavity length, φHR is the phase of the high-reflectivity boundary at the rear end, φR is the weak feedback phase of the dual-channel phase-tunable superlens, and V or T represents the electrical or thermal control state.

[0006] Furthermore, the transmission efficiency of the main transmission output phase region is >70%, and the feedback power of the weak feedback phase region accounts for 0.3%–3% of the output power; in at least one tuning state, the phase change of the main transmission output phase region is ≤0.15π, the phase change of the weak feedback phase region is ≥0.5π, and the phase change range of the weak feedback phase region covers 0–2π.

[0007] Furthermore, the dual-channel phase-adjustable superlens is located on the light-emitting side of the front-end low-reflection light-emitting end face, or on one side of the transparent end cap layer, or in the encapsulation layer in the light-emitting direction of the front-end low-reflection light-emitting end face; The microstructure of the dual-channel phase-tunable superlens is made of TiO2, SiN, a-Si, Si, or low-loss high-refractive-index medium nanopillars / nanofindustries, with a unit period of 350–900 nm, a nanopillar / nanofin height of 300–1200 nm, and a unit lateral dimension of 80–600 nm.

[0008] Furthermore, the main transmission output phase region is located at the center of the optical axis, and the weak feedback phase region is distributed around the main transmission output phase region. The area of ​​the main transmission output phase region accounts for 50%–90%, and the area of ​​the weak feedback phase region accounts for 10%–50%. The weak feedback phase region is far from the optical axis center and is a complete annular region or includes at least two independent phase sub-regions, each phase sub-region being symmetrically or asymmetrically distributed; The tuning controller is positioned at the location corresponding to each region of the weak feedback phase region. The tuning controller employs a zoned tuning electrode, a transparent electrode, or a microheater. The phase adjustment range of the tuning controller is ≥0.5π.

[0009] Furthermore, the operating wavelength of the side-emitting laser unit is 1520–1580 nm. The side-emitting laser unit also includes, in sequence, a substrate layer, a buffer layer, a lower confinement layer, a multi-quantum well active layer, an upper confinement layer, a cladding layer, and an electrode contact layer. The optical waveguide is disposed on the top side of the multi-quantum well active layer and is wrapped by the upper confinement layer and the cladding layer. The optical waveguide is a ridge waveguide or an embedded optical waveguide.

[0010] Furthermore, a tuning method is provided for a superlens tunable laser as described in any of the preceding claims, comprising the following steps: The weak feedback phase region and the feedback phase, voltage, current or heating power of the tuning controller are calibrated, and a lookup table of "tuning amount - feedback phase - lasing wavelength" is established. Based on the target wavelength and the lookup table, the voltage, current, or heating power of the tuning controller is set, and the adjustment action of the tuning controller is controlled to adjust the phase, group delay, or back-coupling phase of the weak feedback phase region, so that the wavelength that satisfies the cavity oscillation condition is moved to the target wavelength.

[0011] Furthermore, a method for fabricating a superlens tunable laser as described in any of the above claims is provided, comprising the following steps: The peripheral structure of the edge-emitting laser unit and the optical waveguide inside it are fabricated. A high-reflectivity rear end boundary and a low-reflectivity front end face are formed at the rear end and the front end of the peripheral structure and the optical waveguide, respectively. The residual reflectivity of the low-reflectivity front end face is less than 1%. A transparent end cap layer is formed in the light emission direction of the low-reflectivity front end face. A dual-channel phase-tunable superlens is formed on a vertical plane in the light-emitting direction of the low-reflection light-emitting end face at the front end. The dual-channel phase-tunable superlens includes a main transmission output phase region on the optical axis and a weak feedback phase region located on the outer periphery of the main transmission output phase region. The transmission efficiency of the main transmission output phase region is >60%, and the feedback power of the weak feedback phase region accounts for 0.1%–8% of the output power. A tuning controller is fabricated at the corresponding position in the weak feedback phase region.

[0012] Furthermore, the peripheral structure of the edge-emitting laser unit and the optical waveguide inside it form a high-reflectivity rear end boundary and a low-reflectivity front end face at the rear end and front end of the peripheral structure and the optical waveguide, respectively, and a transparent end cap layer is formed in the light emission direction of the low-reflectivity front end face, including: An InP laser epitaxial wafer with a gain center of 1520–1580 nm is formed by sequentially growing an n-InP buffer layer, a lower confinement layer, a multi-quantum-well active layer, an upper confinement layer, a p-InP cladding layer, and a p+ contact layer on an n-InP substrate. Ridge waveguides with widths of 1.5–3.5 μm and etching depths of 1.0–2.2 μm are formed using photolithography and ICP / RIE or wet etching; current limiting, passivation windows, and P / N ohmic contacts are then completed. The front and rear end faces are formed by cleaving, etching the reflective surface, or dry processing; the rear end is coated with an HR film or a short DBR reflective boundary to form the rear high reflectivity boundary, the reflectivity of which is 90%–99%; and the front end is deposited with an AR film to form the front low reflectivity light-emitting end face. The transparent endcap layer is formed by deposition, bonding, or transfer on the light-emitting side of the low-reflection light-emitting end face at the front end, and the center of the transparent endcap layer is self-aligned with the light-emitting center of the InP waveguide fundamental mode.

[0013] Furthermore, the formation of a dual-channel phase-tunable superlens on a vertical plane in the light-emitting direction of the low-reflection light-emitting end face at the front end includes: Electron beam exposure, nanoimprinting, or deep ultraviolet lithography are performed on the outer surface of the transparent end cap layer to form the nanostructure of the dual-channel phase-tunable superlens. The main transmission output phase region and the weak feedback phase region are encoded with different nanopillar widths, heights, duty cycles, orientation angles, or material phase states, so that the main transmission output phase region is used to undertake collimation / coupling, and the weak feedback phase region is used to undertake weak feedback for fundamental mode matching. The step of fabricating a tuning controller at the corresponding position in the weak feedback phase region includes: A partitioned microheater, a transparent electrode, a phase change material tuning electrode, or a carrier injection tuning electrode is prepared above, below, or to the side of the weak feedback phase region and electrically isolated from the laser injection electrode. After fabricating the tuning controller at the corresponding position in the weak feedback phase region, the fabrication method further includes the following steps: Complete the interconnection of insulating layer, metal traces, pads and package, so that laser injection, superlens phase tuning and temperature control signals can be independently extracted.

[0014] Compared with existing technologies, the advantages of the superlens tunable laser, tuning method, and fabrication method in this invention are as follows: In this scheme, the high-reflectivity boundary at the rear end, the optical waveguide inside the side-emitting laser unit, the low-reflectivity emitting end face at the front end, and the dual-channel phase-tunable superlens together constitute the laser oscillation cavity. Since the residual reflectivity of the low-reflectivity emitting end face at the front end is less than 1%, most of the laser light exits from the low-reflectivity emitting end face and passes through the transparent end cap layer. During this process, it passes through the dual-channel phase-tunable superlens. Because the transmission efficiency of the main transmission output phase region is >60%, and the feedback power of the weak feedback phase region accounts for 0.1%–8% of the output power, the main transmission output phase region can transmit most of the laser light, collimating the main output light and reducing the divergence angle. The weak feedback phase region is used to extract a small amount of optical power from the area surrounding the main output beam and feed this portion of light back to the fundamental or quasi-fundamental mode of the side-emitting laser unit through phase inversion, angle refraction, polarization selection, or mode matching. Since the main transmission output phase region and the weak feedback phase region are located in the same plane and their phases simultaneously participate in the oscillation conditions of the laser oscillation cavity, the wavelength satisfying the oscillation conditions can be shifted by controlling the phase of the weak feedback phase region through a tuning controller, thereby achieving tuning. This solution achieves laser tuning using only a dual-channel phase-tunable superlens and a tuning controller. Moreover, the main transmission output phase region and the weak feedback phase region of the dual-channel phase-tunable superlens are located on the same plane, occupying little space and reducing the need for external discrete lenses, etalons, mirrors, and mechanical moving parts. This reduces tuning difficulty and can improve chip-level integration and packaging stability. Attached Figure Description

[0015] Figure 1 This is a simplified schematic diagram of the overall structural layout of the superlens tunable laser in this embodiment of the invention; Figure 2 This is a simplified schematic diagram of the longitudinal cross-sectional layout of a portion of the structure in the superlens tunable laser in this embodiment of the invention; Figure 3 This is a schematic diagram of the coding layout of the main transmission output phase region and the weak feedback phase region of the dual-channel phase-tunable superlens in the superlens tunable laser of the present invention. Figure 4 These are the wavelength tuning data for the differential phase drive of the superlens tunable laser in this embodiment of the invention; Figure 5 These are the weak feedback ratio optimization window data for the superlens tunable laser in this embodiment of the invention; Figure 6 This is a flowchart illustrating the tuning method of the superlens tunable laser in this embodiment of the invention. Figure 7 This is a flowchart illustrating the fabrication process of the superlens tunable laser in this embodiment of the invention.

[0016] In the accompanying drawings, the reference numerals represent: 1. Side-emitting laser unit; 11. High-reflectivity rear end boundary; 12. Substrate layer; 13. Lower confinement layer; 14. Multi-quantum-well active layer; 15. Upper confinement layer; 16. Ridge waveguide; 17. Electrode contact layer; 2. Low-reflectivity front end face; 3. Transparent end cap layer; 4. Dual-channel phase-tunable superlens; 41. Main transmission output phase region; 42. Weak feedback phase region; 5. Tuning controller; 6. On-chip monitoring photodetector or side-sampling waveguide. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0018] In this embodiment, combined with Figure 1-3 A superlens tunable laser is provided, comprising an edge-emitting laser unit 1, a front low-reflection emitting end face 2, and a transparent end cap layer 3 arranged sequentially along the optical axis. The edge-emitting laser unit 1 includes an internal optical waveguide and a rear high-reflection boundary 11 located at the end away from the front low-reflection emitting end face 2. The superlens tunable laser also includes a dual-channel phase-tunable superlens 4 and a tuning controller 5 disposed in the light emission direction of the front low-reflection emitting end face 2. The dual-channel phase-tunable superlens 4 includes a main transmission output phase on the optical axis. Region 41 and the weak feedback phase region 42 located on the outer periphery of the same plane as the main transmission output phase region 41 are controlled by the tuning controller 5. The transmission efficiency of the main transmission output phase region 41 is >60%, the feedback power of the weak feedback phase region 42 accounts for 0.1%–8% of the output power, the residual reflectivity of the front low-reflection light-emitting end face 2 is less than 1%, and the rear high-reflection boundary 11, the optical waveguide, the front low-reflection light-emitting end face 2 and the dual-channel phase-tunable superlens 4 together constitute the laser oscillation cavity.

[0019] In this scheme, the high-reflectivity boundary 11 at the rear end, the optical waveguide inside the side-emitting laser unit 1, the low-reflectivity light-emitting end face 2 at the front end, and the dual-channel phase-tunable superlens 4 together constitute the laser oscillation cavity. Since the residual reflectivity of the low-reflectivity light-emitting end face 2 at the front end is less than 1%, most of the laser light is emitted from the low-reflectivity light-emitting end face 2 and passes through the transparent end cap layer 3. During this process, it will pass through the dual-channel phase-tunable superlens 4. Because the transmission efficiency of the main transmission output phase region 41 is >60%, and the feedback power of the weak feedback phase region 42 accounts for 0.1%–8% of the output power, the main transmission output phase region 41 can transmit most of the laser light, collimate the main output light, and reduce the divergence angle. The weak feedback phase region 42 is used to extract a small amount of optical power from the area around the main output beam and feed this part of the light back to the fundamental mode or quasi-fundamental mode of the side-emitting laser unit 1 through phase inversion, angle refraction, polarization selection, or mode matching. Since the main transmission output phase region 41 and the weak feedback phase region 42 are located on the same plane and their phases simultaneously participate in the oscillation conditions of the laser oscillator cavity, the wavelength that satisfies the oscillation conditions can be shifted by controlling the phase of the weak feedback phase region 42 through the tuning controller 5, thereby achieving tuning. This scheme achieves laser tuning only through the dual-channel phase-tunable superlens 4 and the tuning controller 5. Moreover, since the main transmission output phase region 41 and the weak feedback phase region 42 of the dual-channel phase-tunable superlens 4 are located on the same plane, it occupies little space, reduces the need for external discrete lenses, etalons, mirrors, and mechanical moving parts, lowers the tuning difficulty, and can improve chip-level integration and packaging stability.

[0020] Furthermore, the laser oscillation cavity satisfies the oscillation condition 2β(λ)L + φHR(λ) + φR(λ,V,T) = 2πm, where β(λ) is the propagation constant of the optical waveguide, L is the equivalent cavity length, φHR is the phase of the high-reflectivity boundary 11 at the rear end, φR is the weak feedback phase of the dual-channel phase-tunable superlens 4, and V or T represents the electrical or thermal control state. In this scheme, the main transmission output phase region 41 of the dual-channel phase-tunable superlens 4 mainly determines the output beam quality, while the weak feedback phase region 42 mainly determines the feedback phase and the return coupling efficiency. During tuning, the focal length or exit angle of the main transmission output phase region 41 changes little, while the phase change of the weak feedback phase region 42 is large. Under the condition of satisfying the oscillation condition, combined with... Figure 4 By controlling and changing φR through a tuner, the wavelength can be shifted, thus achieving tuning.

[0021] Furthermore, combined Figure 5(The horizontal axis represents the percentage of feedback power in the feedback phase region 42; the left vertical axis corresponds to the solid curve, representing the laser side-mode suppression ratio (SMSR, in dB), reflecting the power difference between the main mode and the side modes. The higher the value, the better the mode selection effect and the higher the mode purity; the right vertical axis corresponds to the dashed curve, representing the degree of mode disturbance / relative noise intensity. The smaller the value on the right, the better the mode stability and the lower the disturbance. The larger the value, the more obvious the mode disturbance.) The transmission efficiency of the main transmission output phase region 41 is >70%, and the feedback power of the weak feedback phase region 42 accounts for 0.3%–3% of the output power. In at least one tuning state, the phase change of the main transmission output phase region 41 is ≤0.15π, the phase change of the weak feedback phase region 42 is ≥0.5π, and the phase change range of the weak feedback phase region 42 covers 0–2π.

[0022] Furthermore, the operating wavelength of the side-emitting laser unit 1 is 1520–1580 nm. The side-emitting laser unit 1 also includes a substrate layer 12, a buffer layer, a lower confinement layer 13, a multi-quantum well active layer 14, an upper confinement layer 15, a cladding layer, and an electrode contact layer 17 in sequence. The optical waveguide is disposed on the top side of the multi-quantum well active layer 14 and is wrapped by the upper confinement layer 15 and the cladding layer. The optical waveguide adopts a ridge waveguide 16 or an embedded optical waveguide. Specifically, the side-emitting laser unit 1 adopts an InP side-emitting laser chip with an operating wavelength of 1520–1580 nm, preferably a 1550 nm C-band side-emitting ridge laser, and a gain region length of 400–900 μm, preferably 600–750 μm. It sequentially includes an n-InP substrate layer 12, a buffer layer (not shown), a lower confinement layer 13, an InP / InGaAsP multi-quantum-well active layer 14, an upper confinement layer 15, a ridge waveguide 16 or an embedded optical waveguide, a p-InP cladding, and a p+ electrode contact layer 17. The n-InP substrate layer 12 has a thickness of 350–625 μm, preferably 400–500 μm, and a doping concentration of 1×10^18–5×10^18 cm^-3, serving as a mechanical support and lower electrode conduction layer; the n-InP buffer layer has a thickness of 100–500 nm, preferably 200–300 nm, to reduce the influence of substrate defects on the active region; the InGaAsP / InGaAlAs lower confinement layer 13 has a thickness of 80–180 nm, preferably 100–150 nm, to optimize the quantum well optical field confinement; the InP / InGaAsP multi-quantum-well active layer 14 has 5–8 quantum wells; the well thickness is 5–8 nm, the barrier thickness is 8–12 nm, and the luminescence center is 1520–1580 nm, used for C-band or extended C-band gain; the InGaAsP / InGaAlAs upper confinement layer 15 has a thickness of 80–180 nm, preferably 100–150 nm. nm, together with the lower confinement layer 13, forms an optical field confinement; p-InP cladding, thickness 1.0–1.8 μm, preferably 1.2–1.5 μm, doped with 5×10^17–2×10^18 cm^-3; p + -InGaAs or p + -InGaAsP electrode contact layer 17, thickness 100–250 nm, preferably 150–200 nm, to reduce P electrode contact resistance; ridge waveguide 16 width 1.5–3.5 μm, preferably 2.0–2.8 μm, to ensure TE0 fundamental mode output and facilitate fundamental mode matching in weak feedback phase region 42; ridge etching depth 1.0–2.2 μm, preferably 1.3–1.8 μm; etching depth error ≤ ±50 nm, used to control lateral mode and threshold current.

[0023] The high-reflection boundary 11 end face HR (High-Reflection) has a coating reflectivity ≥80%, preferably ≥90%, and can be a dielectric film stack or short reflection. It is used to define the rear end boundary of the laser cavity. The low-reflection light-emitting end face 2 AR (Anti-Reflection) has a residual reflectivity ≤1%, preferably ≤0.5%. The end face tilt angle error is ≤±1°, so that the output feedback is mainly defined by the weak feedback phase region 42 of the superlens.

[0024] Furthermore, the dual-channel phase-tunable superlens 4 is located on the light-emitting side of the front low-reflection light-emitting end face 2, or on one side of the transparent end cap layer 3, or in the encapsulation layer in the light-emitting direction of the front low-reflection light-emitting end face 2.

[0025] Specifically, in this embodiment, the dual-channel phase-tunable superlens 4 is disposed on the front or rear face of the transparent end cap layer 3. The transparent end cap layer 3 can be made of SiO2, Al2O3, BCB, polymer, glass, or a combination thereof. The thickness of the transparent end cap layer 3 can be 2–20 μm, preferably 5–12 μm, to balance mode expansion and process tolerance. The thickness error is ≤±5%, and the refractive index range is 1.35–1.75, preferably forming a sufficient phase difference with the refractive index of the superlens unit to ensure the 0–2π phase coverage of the superlens. The absorption loss of the transparent end cap layer 3 at 1550 nm is ≤0.5 dB, preferably ≤0.2 dB, to reduce the additional loss at the light output end. The surface roughness RMS is ≤2 nm, preferably ≤1 nm, to ensure the integrity of the superlens nanostructure pattern. The deviation between the center of the end cap layer and the center of the InP waveguide mode is ≤±1 μm, preferably ≤±0.5 μm, to ensure that the main transmission region and the weak feedback phase region 42 are simultaneously aligned with the fundamental mode. In some implementations, the dual-channel phase-adjustable superlens 4 can also be placed on the front low-reflection light-emitting end face 2.

[0026] Furthermore, the main transmission output phase region 41 is located at the center of the optical axis, and the weak feedback phase region 42 is distributed around the main transmission output phase region 41. The area of ​​the main transmission output phase region 41 accounts for 50%–90%, and the area of ​​the weak feedback phase region 42 accounts for 10%–50%. Specifically, the diameter of the region on the end face of the transparent end cap layer 3 of the dual-channel phase-tunable superlens 4 is 20–100 μm, preferably 40–80 μm. The area of ​​the main transmission output phase region 41 accounts for 50%–90% and is used for main output collimation / coupling, while the area of ​​the weak feedback phase region 42 accounts for 10%–50% and is used to generate weak feedback.

[0027] Furthermore, combined Figure 5The transmission efficiency of the main transmission output phase region 41 is >60%, preferably >70%. The feedback power of the weak feedback phase region 42 accounts for 0.1%–8% of the output power, and the feedback ratio is controlled between 0.3%–3%, preferably less than the strong external cavity feedback threshold. This allows for adjustable phase feedback while avoiding multimode instability caused by strong reflection. The residual reflectivity of the low-reflection light-emitting end face 2 at the front end is less than 1%, so that the output feedback is mainly defined by the weak feedback phase region 42. The feedback light from the weak feedback phase region 42 is matched to the TE0 / TM0 fundamental mode or specified transverse mode of the return-edge emission laser unit 1 through the two-dimensional distribution of the dual-channel phase-tunable superlens 4. In this way, the output power can be guaranteed.

[0028] Furthermore, the weak feedback phase region 42 is located away from the optical axis and is annular or semi-annular; the weak feedback phase region 42 includes at least two independent phase sub-regions, each of which is symmetrically or asymmetrically distributed. The tuning controller 5 is positioned corresponding to the weak feedback phase region 42, and the tuning controller 5 employs a partitioned tuning electrode, a transparent electrode, or a microheater, with a phase adjustment range ≥0.5π.

[0029] Specifically, when the weak feedback phase region 42 is annular, it is coaxial with the main transmission output phase region 41. When the weak feedback phase region 42 is semi-annular, 2-64 sector partitions can be set, preferably 4-16 sector partitions for simpler control. Each sector reflects a small amount of outgoing light back to the InP waveguide fundamental mode through different phase encodings. The feedback ratio of the weak feedback phase region 42 is controlled at 0.3%-3%, preferably less than the strong external cavity feedback threshold. Each partition of the weak feedback phase region 42 is equipped with a corresponding tuning controller 5, so that the phase of each partition can be changed independently, thereby changing the phase boundary of the output end. When the weak feedback phase region 42 is sector partitioned, each partition can be set as a left and right asymmetric phase region located on both sides of the main outgoing light. The left and right phase regions have different two-dimensional phase slopes and are controlled by independent tuning controllers 5 respectively. When the left and right phase regions are tuned in opposite directions, the equivalent deflection angle of the main transmission beam can be canceled out, while the feedback phase changes significantly due to the coherent superposition on both sides.

[0030] The tuning controller 5 is electrically isolated from the laser injection electrode and is used to change the effective phase, reflection phase, group delay, or back-coupling phase of the weak feedback phase region 42. The tuning controller 5 can be a microheater, which is a thermally tuned structure. The material can be Ti / Pt / Au, NiCr, Pt, TiN, or Cr / Au, with a thickness of 50–200 nm and a linewidth of 2–10 μm. It is located on the front or side of the partition and changes the equivalent refractive index of the partition through thermo-optical effects. The tuning controller 5 can also be a transparent electrode, which can be made of ITO, AZO, or an ultrathin metal mesh with a thickness of 20–100 nm and a transmittance of ≥85%. It changes the complex refractive index of the partition region through carrier modulation or electric field modulation. The tuning controller 5 can also be a partitioned tuning electrode, which is a phase-change tuning electrode and is an electro / thermal triggering structure that drives Sb2S3, Sb2Se3, GST, or GSST thin films to generate non-volatile or large phase changes.

[0031] Furthermore, the microstructure of the dual-channel phase-tunable superlens 4 employs TiO2, SiN, a-Si, Si, or low-loss high-refractive-index medium nanopillars / nanofindustries, with a unit cell period of 350–900 nm, a nanopillar / nanofin height of 300–1200 nm, and a unit cell lateral dimension of 80–600 nm. The weak feedback phase region 42 is not a typical reflection region, but a two-dimensional phase-encoded weak feedback region. At the 1550 nm wavelength, the unit cell period is preferably 360–480 nm, and more preferably 400–450 nm, satisfying the subwavelength zero-order diffraction condition near 1550 nm. The nanopillar unit shape can be cylindrical, elliptical, rectangular nanofin, square, or rotationally anisotropic nanopillars, with a nanopillar lateral dimension of 80–420 nm and a nanopillar height of 500–1200 nm. The material can be a TiO2, SiN, a-Si, Si, Al2O3 composite medium, or a high-refractive-index thin film on a low-loss polymer / glass substrate. Phase coverage of 0–2π is achieved by changing the unit diameter, length, width, duty cycle, height, and / or rotation angle. The phase encoding of the weak feedback phase region 42 consists of "back-coupling phase + additional adjustable phase," ensuring that the selected edge or off-axis outgoing light is phase-matched with the InP waveguide fundamental mode after reflection. The microheater alters the refractive index of the weak feedback phase region 42 nanostructure or adjacent tuning layer through thermo-optic effects; the transparent ITO / AZO electrode alters the complex refractive index of the transparent conductive layer or phase change layer through carrier concentration; the Sb₂S₃, Sb₂Se₃, GST, or GSST phase change layer introduces a large phase difference through material phase changes. In some embodiments, the superlens period can be redesigned for the 1310 nm, 1550 nm, or 2 μm wavelength bands.

[0032] Furthermore, the superlens tunable laser may also include an on-chip monitoring photodetector or a side-sampling waveguide 6. Thus, the monitoring signal may include output optical power, side-mode power, feedback intensity, or end-face scattered light. The control circuit adjusts the voltage or heating power of the weak feedback phase region 42 according to the monitoring signal, locking the laser wavelength to the target channel. This solution is applicable to WDM communication, spectral sensing, coherent communication local oscillator sources, and on-chip optical testing.

[0033] The superlens tunable laser of this solution allows the superlens located at the light output position to not only be used for output beam shaping, but also to participate in laser oscillation as a controlled weak feedback and phase selection unit without introducing discrete external cavity lenses, etalons, mirrors or MEMS gratings, thereby achieving wavelength tuning and improving chip-level integration and packaging stability.

[0034] Furthermore, based on the superlens tunable laser described above, combined with Figure 6 A tuning method is provided, comprising the following steps: S1. Calibrate the feedback phase, voltage, current, or heating power of the weak feedback phase region 42 and the tuning controller 5, and establish a lookup table for "tuning quantity - feedback phase - lasing wavelength". By determining the lookup table for "tuning quantity - feedback phase - lasing wavelength" through calibration, a mapping table is formed that corresponds to the feedback phase, voltage, current or heating power, tuning quantity, lasing wavelength, etc. Later, by looking up the table, it can be determined what parameters should be used for the corresponding wavelength output.

[0035] S2. Based on the target wavelength and the lookup table, set the voltage, current, or heating power of the tuning controller 5, and control the adjustment action of the tuning controller 5 to adjust the phase, group delay, or back-coupling phase of the weak feedback phase region 42, so that the wavelength that meets the cavity oscillation condition is moved to the target wavelength. When a target wavelength is needed, the aforementioned lookup table can be consulted first to find the corresponding feedback phase, voltage, current, or heating power parameters, and then the tuning controller 5 can be controlled with the corresponding parameters to adjust the phase of the weak feedback phase region, so that the output wavelength is the target wavelength. It should be understood that the target wavelength needs to be within the tunable range. For example, in this embodiment, the center wavelength can be 1550 nm, the total tuning range is 10–30 nm, and it can be extended to 35 nm after optimization, that is, the wavelength can be adjusted between 1535-1565 nm, the continuous fine-tuning range can be 0.5-5 nm, the wavelength resolution is ≤10 pm, preferably ≤5 pm, the side-mode rejection ratio (SMSR) is ≥35 dB, preferably ≥40 dB, the room temperature output power is 3–10 mW, the threshold current is 20–60 mA, the target linewidth is <1 MHz, and after optimization it is 100–500 kHz, the tuning response time is thermally controlled 0.1–10 ms; the electronic control / ITO is <100 μs, and the operating temperature is 15–70 °C. The parameters are not limited to the limitations in the aforementioned scheme and can be set according to the actual situation.

[0036] Furthermore, based on the superlens tunable laser described above, combined with Figure 7 A method for fabricating a superlens tunable laser is provided, comprising the following steps: S100. Prepare the peripheral structure of the edge-emitting laser unit 1 and the optical waveguide inside it. Form a high-reflectivity boundary 11 at the rear end and a low-reflectivity light-emitting end face 2 at the front end and the rear end of the peripheral structure and the optical waveguide, respectively. The residual reflectivity of the low-reflectivity light-emitting end face 2 at the front end is less than 1%. Form a transparent end cap layer 3 in the light-emitting direction of the low-reflectivity light-emitting end face 2 at the front end.

[0037] Specifically, this step includes the following steps: S101. An n-InP buffer layer, a lower confinement layer 13, a multi-quantum-well active layer 14, an upper confinement layer 15, a p-InP cladding layer, and a p+ contact layer are sequentially grown on an n-InP substrate to form an InP laser epitaxial wafer with a gain center of 1520–1580 nm; specifically, the sequentially grown layers are configured as follows: The n-InP substrate layer 12 has a thickness of 350–625 μm, preferably 400–500 μm, and a doping concentration of 1×10^18–5×10^18 cm^-3, serving as a mechanical support and lower electrode conduction layer; the n-InP buffer layer has a thickness of 100–500 nm, preferably 200–300 nm, to reduce the influence of substrate defects on the active region; the InGaAsP / InGaAlAs lower confinement layer 13 has a thickness of 80–180 nm, preferably 100–150 nm, to optimize the quantum well optical field confinement; the InP / InGaAsP multi-quantum-well active layer 14 has 5–8 quantum wells; the well thickness is 5–8 nm, the barrier thickness is 8–12 nm, and the luminescence center is 1520–1580 nm, used for C-band or extended C-band gain; the InGaAsP / InGaAlAs upper confinement layer 15 has a thickness of 80–180 nm, preferably 100–150 nm. nm, together with the lower confinement layer 13, forms an optical field confinement; p-InP cladding, thickness 1.0–1.8 μm, preferably 1.2–1.5 μm, doped with 5×10^17–2×10^18 cm^-3; p + -InGaAs or p + -InGaAsP electrode contact layer 17, with a thickness of 100–250 nm, preferably 150–200 nm, reduces the contact resistance of the P electrode.

[0038] S102, using photolithography and ICP / RIE or wet etching to form a ridge waveguide 16 with a width of 1.5–3.5 μm and an etching depth of 1.0–2.2 μm; completing current limiting, passivation windowing and P / N ohmic contact.

[0039] Specifically, the ridge waveguide 16 is used to ensure the TE0 fundamental mode output, facilitating fundamental mode matching in the weak feedback phase region 42. The ridge etching depth is 1.0–2.2 μm, preferably 1.3–1.8 μm; the etching depth error is ≤±50 nm, used to control the lateral mode and threshold current; the etching method is ICP / RIE dry etching or wet etching; the sidewall angle is 80°–90°, preferably ≥85°, used to form low-scattering waveguide sidewalls; the sidewall roughness RMS is ≤10 nm, preferably ≤5 nm, to reduce waveguide scattering loss; the passivation layer is SiNx / SiO2 / Al2O3, with a thickness of 100–400 nm, preferably 150–250 nm, used to achieve electrical isolation and reduce surface recombination; the P electrode is Ti / Pt / Au, Cr / Au, or Ti / Au, with a total thickness of 200–800 nm and a window width of 2–5 μm, making ohmic contact with the laser injection region; N The electrodes are made of AuGe / Ni / Au or Ge / Au / Ni / Au, with a total thickness of 200–800 nm; annealing is performed at 380–430 °C for 30–90 s to form a low-resistance n-side ohmic contact.

[0040] S103. The front and rear end faces are formed by cleaving, etching the reflective surface, or dry processing. The rear end is coated with an HR film or a short DBR reflective boundary to form a high-reflection rear end boundary 11. The reflectivity of the high-reflection rear end boundary 11 is 90%–99%. An AR film is deposited at the front end to form a low-reflection front end face 2. The high-reflection rear end face 11 has a reflectivity of ≥80%, preferably ≥90%, and can be a dielectric film stack or a short reflector. It is used to define the rear end boundary of the laser cavity. The residual reflectivity of the low-reflection front end face 2 AR is ≤1%, preferably ≤0.5%. The end face tilt angle error is ≤±1°, so that the output feedback is mainly defined by the weak feedback phase region 42 of the superlens.

[0041] S104. A transparent endcap layer 3 is deposited, bonded, or transferred on the light-emitting side of the low-reflection light-emitting end face 2 at the front end, and the center of the transparent endcap layer 3 is self-aligned with the light-emitting center of the InP waveguide fundamental mode. The transparent endcap layer 3 can be fabricated by depositing / bonding a transparent medium on the front end face of the laser and then patterning it, which is suitable for sheet-level or chip-level end face integration; the transparent endcap layer 3 can also be formed by prefabricating a transparent endcap chip with a superlens and then aligning and bonding it with the InP light-emitting end face, which is suitable for the first-round prototype preparation and has higher process controllability. The transparent end cap layer 3 can be made of SiO2, Al2O3, BCB, low-loss polymer, glass, or a combination thereof, to provide a flat fabrication interface for the end-face superlens. The thickness can be 2–20 μm, preferably 5–12 μm, with a thickness error ≤ ±5%. The refractive index ranges from 1.35 to 1.75, preferably forming a sufficient phase difference with the refractive index of the superlens unit to ensure 0–2π phase coverage of the superlens. The absorption loss of the transparent end cap layer 3 at 1550 nm is ≤ 0.5 dB, preferably ≤ 0.2 dB, thereby reducing additional loss at the light-emitting end. The surface roughness RMS is ≤ 2 nm, preferably ≤ 1 nm, to ensure the integrity of the superlens nanostructure pattern. The deviation between the center of the end cap layer and the center of the InP waveguide mode is ≤ ± 1 μm, preferably ≤ ± 0.5 μm, to ensure that the main transmission region and the weak feedback phase region 42 are simultaneously aligned with the fundamental mode.

[0042] S200. A dual-channel phase-tunable superlens 4 is formed on a vertical plane in the light-emitting direction of the low-reflection light-emitting end face 2 at the front end. The dual-channel phase-tunable superlens 4 includes a main transmission output phase region 41 on the optical axis and a weak feedback phase region 42 located on the outer periphery of the main transmission output phase region 41. The transmission efficiency of the main transmission output phase region 41 is >60%, and the feedback power of the weak feedback phase region 42 accounts for 0.1%–8% of the output power.

[0043] Specifically, electron beam lithography, nanoimprinting, or deep ultraviolet lithography are performed on the outer surface of the transparent end cap layer 3 to form a nanostructure of a dual-channel phase-tunable superlens 4. The main transmission output phase region 41 and the weak feedback phase region 42 employ different nanopillar widths, heights, duty cycles, orientation angles, or material phase encodings, so that the main transmission output phase region 41 is used for collimation / coupling, and the weak feedback phase region 42 is used for weak feedback in fundamental mode matching. In one embodiment, the dual-channel phase-tunable superlens 4 can be disposed on the light-emitting side of the transparent end cap layer 3. In this case, the transparent end cap layer 3 is first formed on the light-emitting side of the low-reflection light-emitting end face 2 at the front end, and then the dual-channel phase-tunable superlens 4 is formed on the light-emitting side of the transparent end cap layer 3. In another embodiment, the dual-channel phase-tunable superlens 4 can be disposed on the light-incident side of the transparent end cap layer 3. In this approach, the dual-channel phase-tunable superlens 4 is first formed on the light-incident side of the transparent end cap layer 3, and then the side of the transparent end cap layer 3 with the dual-channel phase-tunable superlens 4 is aligned and bonded to the InP light-emitting end face. Alternatively, the dual-channel phase-tunable superlens 4 can be formed directly on the low-reflection light-emitting end face 2 before forming the transparent end cap layer 3.

[0044] The main transmission output phase region 41 is located at the center of the optical axis, and the weak feedback phase region 42 is distributed around the main transmission output phase region 41. The area of ​​the main transmission output phase region 41 accounts for 50%–90%, and the area of ​​the weak feedback phase region 42 accounts for 10%–50%. Specifically, the diameter of the area on the end face of the transparent end cap layer 3 of the dual-channel phase-tunable superlens 4 is 20–100 μm, preferably 40–80 μm. The area of ​​the main transmission output phase region 41 accounts for 50%–90% and is used for main output collimation / coupling or divergence angle compression, while the area of ​​the weak feedback phase region 42 accounts for 10%–50% and is used to generate weak feedback.

[0045] The transmission efficiency of the main transmission output phase region 41 is >60%, preferably >70%. The feedback power of the weak feedback phase region 42 accounts for 0.1%–8% of the output power, and the feedback ratio is controlled at 0.3%–3%, preferably less than the strong external cavity feedback threshold. This can form adjustable phase feedback and avoid strong reflection causing multimode instability. The residual reflectivity of the front-end low-reflection light-emitting end face 2 is less than 1%, so that the output feedback is mainly defined by the weak feedback phase region 42. The feedback light of the weak feedback phase region 42 is matched to the TE0 / TM0 fundamental mode or the specified transverse mode of the return-edge emission laser unit 1 through the two-dimensional distribution of the dual-channel phase-tunable superlens 4.

[0046] The microstructure of the dual-channel phase-tunable superlens 4 employs TiO2, SiN, a-Si, Si, or low-loss, high-refractive-index dielectric nanopillars / nanofindustries. The unit cell period is 350–900 nm, the nanopillar / nanofin height is 300–1200 nm, and the unit cell lateral dimension is 80–600 nm. The weak feedback phase region 42 is not a typical reflection region but a two-dimensional phase-encoded weak feedback region. At the 1550 nm wavelength, the unit cell period is preferably 360–480 nm, and further preferably 400–450 nm, satisfying the subwavelength zero-order diffraction condition near 1550 nm. The nanopillar unit shape can be cylindrical, elliptical, rectangular nanofin, square, or rotationally anisotropic nanopillars. The lateral dimension of the nanopillar is 80–420 nm, and the height is 500–1200 nm, with a height error ≤ ±5%, thus achieving 0–2π phase coverage. The material can be a TiO2, SiN, a-Si, Si, Al2O3 composite medium, or a high-refractive-index thin film on a low-loss polymer / glass substrate. The phase quantization level is ≥8 levels, preferably ≥16 levels or near-continuous phase, to reduce wavefront error and return coupling loss. The phase error MS is ≤π / 8, preferably ≤π / 12, to ensure predictable feedback phase. 0–2π phase coverage can be obtained by changing the unit diameter, length, width, duty cycle, height, and / or rotation angle. During tuning, the phase change in the main transmission output phase region 41 is ≤0.15π, and the main emission angle change is ≤1°, preferably ≤0.5°, to ensure main output stability. The proportion of the feedback light in the weak feedback phase region 42 coupled to the TE0 / TM0 fundamental mode is ≥30%, preferably ≥50%. The phase encoding of the weak feedback phase region 42 consists of "re-coupling phase + additional adjustable phase", so that the selected edge or off-axis outgoing light is phase matched with the InP waveguide fundamental mode after being reflected back.

[0047] S300, A tuning controller 5 is prepared at the corresponding position in the weak feedback phase region 42.

[0048] This includes: fabricating partitioned microheaters, transparent electrodes, phase change material tuning electrodes, or carrier injection tuning electrodes above, below, or to the side of the weak feedback phase region 42, and electrically isolating them from the laser injection electrode.

[0049] Specifically, the tuning controller 5 is positioned corresponding to the weak feedback phase region 42. The tuning controller 5 employs a partitioned tuning electrode, a transparent electrode, or a microheater, and its phase adjustment range is ≥0.5π. Each partition of the weak feedback phase region 42 is equipped with a corresponding tuning controller 5, allowing the phase of each partition to be changed independently, thereby altering the phase boundary at the output. When the weak feedback phase region 42 is a fan-shaped partition, each partition can be configured as a left and right asymmetric phase region located on either side of the main output beam. The left and right phase regions have different two-dimensional phase slopes and are controlled by independent tuning controllers 5. When tuning amounts in opposite directions are applied to the left and right phase regions, the equivalent deflection angle of the main transmitted beam can cancel each other out, while the feedback phase changes significantly due to the coherent superposition of the two sides.

[0050] The tuning controller 5 can be a microheater, which is a thermally tuned structure. The material can be Ti / Pt / Au, NiCr, Pt, TiN, or Cr / Au, with a thickness of 50–200 nm. It is used for thermo-optical phase tuning, with a linewidth of 2–10 μm, balancing resistance, thermal efficiency, and process resolution. The resistance is 50–1000 Ω, preferably 100–500 Ω, to facilitate low-current driving. The tuning power is 0–30 mW per zone, preferably 1–15 mW, to achieve phase change control in the weak feedback phase zone and control thermal crosstalk. The insulating spacer layer can be SiO2 / Al2O3 / SiNx, with a thickness of 100–800 nm, preferably 200–500 nm, to prevent electrode absorption and leakage. During phase adjustment, the temperature rise of the main transmission phase zone is ≤5 °C or the phase change is ≤0.15π, ensuring that the main light output remains basically unchanged. The heater is located on the front or side of the zone and changes the equivalent refractive index of the zone through the thermo-optical effect. The tuning controller 5 can be a transparent electrode, made of ITO, AZO, or an ultrathin metal mesh, with a thickness of 20–100 nm and a transmittance ≥85%. It changes the complex refractive index of a partitioned region through carrier modulation or electric field modulation. The tuning controller 5 can also employ partitioned tuning electrodes, which are phase-change tuning electrodes and serve as the electro-thermal triggering structure for driving Sb₂S₃, Sb₂Se₃, GST, or GSST thin films, used to generate non-volatile or large phase changes. The tuning response is thermally controlled at 0.1–20 ms, preferably ≤10 ms; electrically controlled at 0.1–100 μs, selectable based on the adaptability of the tuning structure.

[0051] The S400 completes the insulation layer, metal traces, pads, and package interconnection, allowing for independent extraction of laser injection, superlens phase tuning, and temperature control signals. This enables independent control of the weak feedback phase region 42, facilitating tuning.

[0052] After fabrication, the phase distribution of the superlens is calculated using FDTD / RCWA, the laser cavity mode is calculated using the transfer matrix or traveling wave model, and wavelength tuning calibration is performed. The voltage, current, or heating power of the tuning controller 5 corresponding to the weak feedback phase region 42 is scanned, and the center wavelength, SMSR, output power, and main emission angle are recorded. A lookup table of tuning quantity, feedback phase, and wavelength is established. Then, tuning can be performed according to the lookup table and the target wavelength to output laser light at the target wavelength.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A superlens tunable laser, comprising an edge-emitting laser unit, a front low-reflection emitting end face, and a transparent end cap layer arranged sequentially along an optical axis, wherein the edge-emitting laser unit includes an internal optical waveguide and a rear high-reflection boundary located at the end away from the front low-reflection emitting end face, characterized in that, The superlens tunable laser also includes a dual-channel phase-tunable superlens and a tuning controller disposed on the light output direction of the low-reflection light output end face at the front end. The dual-channel phase-tunable superlens includes a main transmission output phase region on the optical axis and a weak feedback phase region located on the outer periphery of the same plane as the main transmission output phase region. The tuning controller is used to control the phase of the weak feedback phase region. The transmission efficiency of the main transmission output phase region is >60%, the feedback power of the weak feedback phase region accounts for 0.1%–8% of the output power, the residual reflectivity of the front low-reflection light-emitting end face is less than 1%, and the rear high-reflection boundary, the optical waveguide, the front low-reflection light-emitting end face and the dual-channel phase-tunable superlens together constitute the laser oscillation cavity.

2. The metalens-tunable laser of claim 1, wherein, The laser oscillation cavity satisfies the oscillation condition 2β(λ)L + φHR(λ) + φR(λ,V,T) = 2πm, where β(λ) is the propagation constant of the optical waveguide, L is the equivalent cavity length, φHR is the phase of the high-reflectivity boundary at the rear end, φR is the weak feedback phase of the dual-channel phase-tunable superlens, and V or T represents the electrical or thermal control state.

3. The metasurface tunable laser of claim 2, wherein, The transmission efficiency of the main transmission output phase region is >70%, and the feedback power of the weak feedback phase region accounts for 0.3%–3% of the output power. In at least one tuning state, the phase change of the main transmission output phase region is ≤0.15π, the phase change of the weak feedback phase region is ≥0.5π, and the phase change range of the weak feedback phase region covers 0–2π.

4. The superlens tunable laser according to claim 1, characterized in that, The dual-channel phase-adjustable superlens is located on the light-emitting side of the front-end low-reflection light-emitting end face, or on one side of the transparent end cap layer, or in the encapsulation layer in the light-emitting direction of the front-end low-reflection light-emitting end face; The microstructure of the dual-channel phase-tunable superlens is made of TiO2, SiN, a-Si, Si, or low-loss high-refractive-index medium nanopillars / nanofindustries, with a unit period of 350–900 nm, a nanopillar / nanofin height of 300–1200 nm, and a unit lateral dimension of 80–600 nm.

5. The superlens tunable laser according to claim 1, characterized in that, The main transmission output phase region is located at the center of the optical axis, and the weak feedback phase region is distributed around the main transmission output phase region. The area of ​​the main transmission output phase region accounts for 50%–90%, and the area of ​​the weak feedback phase region accounts for 10%–50%. The weak feedback phase region is far from the optical axis and is either a complete annular region or includes at least two independent phase sub-regions, each phase sub-region being symmetrically or asymmetrically distributed. The tuning controller is positioned at the location corresponding to each region of the weak feedback phase region. The tuning controller employs a zoned tuning electrode, a transparent electrode, or a microheater. The phase adjustment range of the tuning controller is ≥0.5π.

6. The superlens tunable laser according to any one of claims 1-5, characterized in that, The operating wavelength of the side-emitting laser unit is 1520–1580 nm. The side-emitting laser unit also includes, in sequence, a substrate layer, a buffer layer, a lower confinement layer, a multi-quantum well active layer, an upper confinement layer, a cladding layer, and an electrode contact layer. The optical waveguide is disposed on the top side of the multi-quantum well active layer and is wrapped by the upper confinement layer and the cladding layer. The optical waveguide is a ridge waveguide or an embedded optical waveguide.

7. A tuning method for a superlens tunable laser as described in any one of claims 1-6, characterized in that, Includes the following steps: The weak feedback phase region and the feedback phase, voltage, current or heating power of the tuning controller are calibrated, and a lookup table of "tuning amount - feedback phase - lasing wavelength" is established. Based on the target wavelength and the lookup table, the voltage, current, or heating power of the tuning controller is set, and the adjustment action of the tuning controller is controlled to adjust the phase, group delay, or back-coupling phase of the weak feedback phase region, so that the wavelength that satisfies the cavity oscillation condition is moved to the target wavelength.

8. A method for fabricating a superlens tunable laser as described in any one of claims 1-6, characterized in that, Includes the following steps: The peripheral structure of the edge-emitting laser unit and the optical waveguide inside it are fabricated. A high-reflectivity rear end boundary and a low-reflectivity front end face are formed at the rear end and the front end of the peripheral structure and the optical waveguide, respectively. The residual reflectivity of the low-reflectivity front end face is less than 1%. A transparent end cap layer is formed in the light emission direction of the low-reflectivity front end face. A dual-channel phase-tunable superlens is formed on a vertical plane in the light-emitting direction of the low-reflection light-emitting end face at the front end. The dual-channel phase-tunable superlens includes a main transmission output phase region on the optical axis and a weak feedback phase region located on the outer periphery of the main transmission output phase region. The transmission efficiency of the main transmission output phase region is >60%, and the feedback power of the weak feedback phase region accounts for 0.1%–8% of the output power. A tuning controller is fabricated at the corresponding position in the weak feedback phase region.

9. The preparation method according to claim 8, characterized in that, The peripheral structure of the edge-emitting laser unit and the optical waveguide inside it are configured to form a high-reflectivity rear end boundary and a low-reflectivity front end face at the rear and front ends of the peripheral structure and the optical waveguide, respectively. A transparent end cap layer is formed in the light emission direction of the low-reflectivity front end face, comprising: An InP laser epitaxial wafer with a gain center of 1520–1580 nm is formed by sequentially growing an n-InP buffer layer, a lower confinement layer, a multi-quantum-well active layer, an upper confinement layer, a p-InP cladding layer, and a p+ contact layer on an n-InP substrate. Ridge waveguides with widths of 1.5–3.5 μm and etching depths of 1.0–2.2 μm are formed using photolithography and ICP / RIE or wet etching; current limiting, passivation windowing, and P / N ohmic contacts are then completed. The front and rear end faces are formed by cleaving, etching the reflective surface, or dry processing; the rear end is coated with an HR film or a short DBR reflective boundary to form the rear high reflectivity boundary, the reflectivity of which is 90%–99%; and the front end is deposited with an AR film to form the front low reflectivity light-emitting end face. The transparent endcap layer is formed by deposition, bonding, or transfer on the light-emitting side of the low-reflection light-emitting end face at the front end, and the center of the transparent endcap layer is self-aligned with the light-emitting center of the InP waveguide fundamental mode.

10. The preparation method according to claim 8, characterized in that, The dual-channel phase-tunable superlens formed on a vertical plane in the light-emitting direction of the low-reflection light-emitting end face at the front end includes: Electron beam exposure, nanoimprinting, or deep ultraviolet lithography are performed on the outer surface of the transparent end cap layer to form the nanostructure of the dual-channel phase-tunable superlens. The main transmission output phase region and the weak feedback phase region are encoded with different nanopillar widths, heights, duty cycles, orientation angles, or material phase states, so that the main transmission output phase region is used to undertake collimation / coupling, and the weak feedback phase region is used to undertake weak feedback for fundamental mode matching. The step of fabricating a tuning controller at the corresponding position in the weak feedback phase region includes: A partitioned microheater, a transparent electrode, a phase change material tuning electrode, or a carrier injection tuning electrode is prepared above, below, or to the side of the weak feedback phase region and electrically isolated from the laser injection electrode. After fabricating the tuning controller at the corresponding position in the weak feedback phase region, the fabrication method further includes the following steps: Complete the interconnection of insulating layer, metal traces, pads and package, so that laser injection, superlens phase tuning and temperature control signals can be independently extracted.

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