A photonic crystal laser and a forming process thereof

Abstract

The application provides a photonic crystal laser and a forming process thereof. The photonic crystal laser comprises a substrate, a laser generating structure, a ridge waveguide structure, a first electrode, a second electrode, an end surface photonic crystal and a side wall photonic crystal. The laser generating structure is arranged on the substrate. The first electrode and the second electrode are arranged on the substrate and the ridge waveguide structure. The laser generating structure can form laser by injecting current. A step is formed between the ridge waveguide structure and the laser generating structure. The end surface photonic crystal is etched on both sides of the length direction of the step, and the high order longitudinal mode of the laser generating structure can be suppressed. The side wall photonic crystal is etched on both sides of the width direction of the step, and the high order transverse mode of the laser generating structure can be suppressed. The high order transverse mode is suppressed without arranging a narrow ridge waveguide structure. The laser can meet the requirements of suppressing the high order transverse mode and the high order longitudinal mode, and can realize high power laser output.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser, in particular to a photonic crystal laser and a forming process thereof. BACKGROUND

[0002] The traditional Fabry-Perot (FP) laser has the inherent defect of multi-mode oscillation due to its open resonant cavity structure.

[0003] Specifically, the suppression of transverse modes needs to rely on narrow ridge waveguides, and the ridge width of the ridge waveguide structure usually needs to be compressed to below 3 um, which leads to a sharp decrease in process tolerance and a significant increase in series resistance, resulting in an increase in power consumption of the laser by more than 40%, and the high-order transverse modes are still easily excited under a large current injection. In addition, the cleaved facet reflection spectrum has a wide spectral characteristic, with a reflectivity of about 30%, and the adjacent longitudinal mode spacing is inversely proportional to the cavity length, with a typical value of about 0.8 nm at a cavity length of 300 um, resulting in concurrent multi-longitudinal-mode.

[0004] Therefore, the existing FP laser is difficult to simultaneously suppress high-order transverse modes and high-order longitudinal modes while achieving high-power output of laser, and it is difficult to meet the needs of high-precision gas sensing or high-speed communication. SUMMARY

[0005] The present application provides a photonic crystal laser and a forming process thereof, which etches a photonic crystal structure in the FP laser to suppress high-order transverse modes and high-order longitudinal modes through the photonic crystal structure, thereby solving the technical problem that the existing laser is difficult to simultaneously suppress high-order transverse modes and high-order longitudinal modes while achieving high-power output of laser.

[0006] In one aspect, the present application provides a photonic crystal laser, comprising:

[0007] a substrate;

[0008] a laser generating structure disposed on the substrate;

[0009] a ridge waveguide structure disposed on the side of the laser generating structure away from the substrate, and a step formed between the ridge waveguide structure and the laser generating structure;

[0010] a first electrode disposed on the side of the substrate away from the laser generating structure;

[0011] a second electrode disposed on the side of the ridge waveguide structure away from the substrate;

[0012] a facet photonic crystal etched on both sides of the step in the length direction, for suppressing high-order longitudinal modes of the laser generating structure;

[0013] The sidewall photonic crystal is etched on both sides of the step width direction, and is used for inhibiting high-order transverse modes of the laser generation structure.

[0014] In some embodiments, the photonic crystal period Λ1 of the end surface photonic crystal is between 250-320 nm, and the photonic crystal duty cycle is between 0.3-0.4.

[0015] In some embodiments, the photonic crystal period Λ1 of the end surface photonic crystal satisfies: β·Λ1=2π, where β is the propagation constant of the laser fundamental mode.

[0016] In some embodiments, the length of the sidewall photonic crystal is more than 80% of the length of the ridge waveguide structure.

[0017] In some embodiments, the photonic crystal period Λ2 of the sidewall photonic crystal is between 250-320 nm.

[0018] In some embodiments, the distance between the etched bottom of the sidewall photonic crystal and the quantum well active region of the laser generation structure is at least 20 nm.

[0019] In some embodiments, the distance between the sidewall photonic crystal and the ridge waveguide structure is within 100 nm.

[0020] In some embodiments, the width of the ridge waveguide structure ranges between 7-9 μm.

[0021] In some embodiments, the laser generation structure comprises, from bottom to top, a lower confinement layer, a quantum well active region, and an upper confinement layer, the ridge waveguide structure is formed on the upper confinement layer, and the step is formed between the ridge waveguide structure and the upper confinement layer.

[0022] In another aspect, the present application also provides a forming process of a photonic crystal laser, comprising the following steps:

[0023] Performing epitaxial growth on a substrate to form an epitaxial structure having a ridge waveguide layer;

[0024] Etching the circumferential side of the ridge waveguide layer of the epitaxial structure to obtain a laser generation structure having a ridge waveguide structure, and forming a step at the etched part;

[0025] Etching to form an end surface photonic crystal on both sides of the step length direction, and etching to form a sidewall photonic crystal on both sides of the step width direction;

[0026] Depositing a first electrode on the bottom of the substrate, and depositing a second electrode on the top of the ridge waveguide structure.

[0027] The photonic crystal laser provided in the application comprises a substrate, a laser generating structure, a ridge waveguide structure, a first electrode, a second electrode, an end surface photonic crystal and a side wall photonic crystal. The laser generating structure is arranged on the substrate. The first electrode and the second electrode are arranged on the substrate and the ridge waveguide structure. The laser generating structure can form laser by injecting current. The ridge waveguide structure can limit the propagation range of the laser. The ridge waveguide structure and the laser generating structure form a step. The end surface photonic crystal is etched on both sides of the length direction of the step, which can suppress the high-order longitudinal mode of the laser generating structure. The side wall photonic crystal is etched on both sides of the width direction of the step, which can suppress the high-order transverse mode of the laser generating structure. The side wall photonic crystal can suppress the high-order transverse mode, so that the narrow ridge waveguide structure is not needed to suppress the high-order transverse mode. The power of the laser is effectively increased. The end surface photonic crystal can suppress the high-order longitudinal mode, so that the laser can suppress the high-order transverse mode and the high-order longitudinal mode and output high-power laser. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings incorporated in the specification and forming a part thereof illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0029] Figure 1 is a top view of the photonic crystal laser provided in the embodiments of the application;

[0030] Figure 2 is a sectional view along the line A-A in Figure 1 ;

[0031] Figure 3 is a sectional view along the line B-B in Figure 1 ;

[0032] Figure 4 is a flow chart of the forming process of the photonic crystal laser provided in the embodiments of the application;

[0033] Figure 5 is a structural schematic diagram of the photonic crystal laser provided in the embodiments of the application after the epitaxial structure is formed in the forming process;

[0034] Figure 6 is a structural schematic diagram of the photonic crystal laser provided in the embodiments of the application after the step is etched in the forming process;

[0035] Figure 7 is a structural schematic diagram of the photonic crystal laser provided in the embodiments of the application after the end surface photonic crystal is etched in the forming process;

[0036] Figure 8 is a structural schematic diagram of the photonic crystal laser provided in the embodiments of the application after the side wall photonic crystal is etched in the forming process;

[0037] Figure 9 Fig. 1 is a structure schematic diagram of a photonic crystal laser after a first electrode and a second electrode are deposited in a forming process of the photonic crystal laser provided by an embodiment of the present application.

[0038] Reference signs:

[0039] 10 - substrate;

[0040] 20 - laser generating structure; 21 - lower confining layer; 22 - quantum well active region; 23 - upper confining layer;

[0041] 30 - ridge waveguide structure; 31 - cap layer; 30a - step; 30b - waveguide layer;

[0042] 40 - first electrode;

[0043] 50 - second electrode;

[0044] 60 - end surface photonic crystal;

[0045] 70 - side wall photonic crystal;

[0046] 80 - epitaxial structure.

[0047] The specific embodiments have been shown and described in the above drawings and written description with the specific reference to the drawings by way of examples only. These embodiments are meant to be illustrative only and not limiting of the scope of the application as defined by the appended claims. It will be apparent to those skilled in the art that various modifications, both as to the details of structure and the scope of the disclosed embodiments, can be made without departing from the scope of the application. DETAILED DESCRIPTION

[0048] The illustrative examples set forth herein will vary from one another in different ways. Some examples will be described in detail in the following description and explained with reference to the drawings. The following description will often use selective referencing to the drawings. As indicated above, the same reference numerals will be used throughout the drawings and the following description to refer to the same or like parts. The following description is intended to enable those skilled in the art to be able to practice the examples as claimed without necessarily being limited to only these embodiments delineated and described. The scope of the disclosure encompasses numerous alternatives, modifications and equivalents.

[0049] The traditional Fabry-Perot (FP) cavity laser includes a substrate, a laser generating structure, a ridge waveguide structure and an electrode structure. The electrode structure injects current to the laser generating structure, so that the quantum well active region of the laser generating structure forms laser. The ridge waveguide structure can limit the propagation range of the laser. Due to the open resonant cavity structure, the laser has the inherent defect of multi-mode oscillation. Specifically, the suppression of high-order transverse modes needs to rely on narrow ridge waveguide, and the ridge width of the ridge waveguide structure usually needs to be compressed to below 3 μm, which leads to a sharp decrease in process tolerance and a significant increase in series resistance, an increase in injection current, and an increase in power consumption of the laser by more than 40%. At the same time, under the injection of large current, the high-order transverse mode is still easy to be excited. At the same time, due to the wide spectrum characteristics of the cleaved facet reflection spectrum, the longitudinal mode selection mechanism is also missing, and the interval between adjacent longitudinal modes is inversely proportional to the cavity length, with a typical value of about 0.8 nm at a cavity length of 300 μm, resulting in concurrent multi-longitudinal-mode, and the spectral linewidth is generally greater than 2 nm, which is difficult to meet the needs of high-precision gas sensing or high-speed communication.

[0050] In the related art, in order to effectively suppress high-order transverse modes, the mainstream scheme adopts a distributed feedback laser. The distributed feedback laser needs to be twice epitaxially grown or electron beam lithography to make a Bragg grating, and the cost is three to five times higher than that of the FP laser. Moreover, the yield of the distributed feedback laser is significantly reduced due to the twice epitaxy. In addition, the wavelength flexibility of the distributed feedback laser is also limited, and the tuning range is limited to the fixed grating period, which is difficult to adapt to multi-band application scenarios.

[0051] In order to solve the technical problem that the laser is difficult to simultaneously suppress high-order transverse modes and high-order longitudinal modes, and realize high-power output of the laser, an embodiment of the present application provides a photonic crystal laser. The photonic crystal laser suppresses high-order transverse modes and high-order longitudinal modes through a photonic crystal structure, solves the problem that the existing laser is difficult to simultaneously suppress high-order transverse modes and high-order longitudinal modes, and realizes high-power output of the laser. Moreover, the production cost of the laser can be avoided to be too high, and the yield can be avoided to be too low.

[0052] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail in the specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in detail in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0053] In order to better understand the present application, the following will be combined with Figures 1 to 9 The technical solutions of the present application will be described in detail:

[0054] As Figure 1 , Figure 2 and Figure 3As shown in the figure, the photonic crystal laser provided by the embodiment of the present application comprises a substrate 10, a laser generation structure 20, a ridge waveguide structure 30, a first electrode 40 and a second electrode 50. The laser generation structure 20 is arranged on the substrate 10. The ridge waveguide structure 30 is arranged on the side of the laser generation structure 20 away from the substrate 10. The ridge waveguide structure 30 and the laser generation structure 20 form a step 30a. The first electrode 40 is arranged on the side of the substrate 10 away from the laser generation structure 20. The second electrode 50 is arranged on the side of the ridge waveguide structure 30 away from the substrate 10.

[0055] Specifically, the photonic crystal laser comprises a substrate 10, a laser generation structure 20, a ridge waveguide structure 30, a first electrode 40, a second electrode 50, an end surface photonic crystal 60 and a side wall photonic crystal 70. The laser generation structure 20 is arranged on the substrate 10. The laser generation structure 20 realizes the generation of laser by specific design and physical mechanism. When a forward bias voltage is applied to the p-n junction of the laser generation structure 20, the current is injected into the quantum well active region 22 of the laser generation structure 20. The electrons and holes are combined to generate photons. The generated photons induce stimulated emission in the active region to generate more photons, form optical amplification and finally form stable laser. The first electrode 40 and the second electrode 50 are arranged on the substrate 10 and the ridge waveguide structure 30. The first electrode 40 and the second electrode 50 can inject the current to induce photons into the laser generation structure 20, so that the laser generation structure 20 forms laser. The ridge waveguide structure 30 can limit the optical field and limit the propagation range of the laser to increase the output power of the laser.

[0056] To realize the suppression of high-order transverse mode and high-order longitudinal mode of laser, the embodiment of the present application etches the photonic crystal structure at the step 30a. Specifically, as shown in the figures of Figure 1 、 Figure 2 and Figure 3 , the photonic crystal laser provided by the embodiment of the present application further comprises an end surface photonic crystal 60 and a side wall photonic crystal 70. The end surface photonic crystal 60 is etched on both sides of the length direction of the step 30a, which is used to suppress the high-order longitudinal mode of the laser generation structure 20. The side wall photonic crystal 70 is etched on both sides of the width direction of the step 30a, which is used to suppress the high-order transverse mode of the laser generation structure 20.

[0057] The sidewall photonic crystal 70 is etched on both sides of the step 30a in the width direction, which can suppress higher-order transverse modes on both sides of the ridge waveguide structure 30. This eliminates the need for a narrow ridge waveguide structure 30 to suppress higher-order transverse modes, effectively reducing the laser's current and power consumption, and increasing the laser's power. Through the suppression of higher-order transverse modes by the sidewall photonic crystal 70 and the suppression of higher-order longitudinal modes by the end-face photonic crystal 60, the laser can both suppress higher-order transverse and longitudinal modes and achieve high-power laser output, meeting the requirements of high-precision gas sensing or high-speed communication. The end-face photonic crystal 60 and the sidewall photonic crystal 70 can be formed simply by etching the step 30a, without the need for secondary epitaxial growth, effectively controlling the laser's production cost and improving the laser's yield.

[0058] In this embodiment, the laser propagates along the length of the laser generating structure 20. A resonant cavity is formed between the two end faces of the laser generating structure 20 along its length. The two end faces of the laser generating structure 20 along its length form the cavity surface end of the resonant cavity. The length direction of the step 30a is the propagation direction of the laser, and the width direction of the step 30a is perpendicular to the propagation direction of the laser.

[0059] In some embodiments, such as Figure 2 and Figure 3 As shown, the laser generating structure 20 includes a lower confinement layer 21, a quantum well active region 22, and an upper confinement layer 23 arranged sequentially from bottom to top. The ridge waveguide structure 30 is formed on the upper confinement layer 23, forming a step 30a between it and the upper confinement layer 23. Specifically, the substrate 10 layer serves as the basis for the growth of the entire laser generating structure 20, providing space for the lower confinement layer 21, the quantum well active region 22, and the upper confinement layer 23. The quantum well active layer can effectively trap electrons and holes, improving the recombination efficiency of charge carriers, thereby generating more photons. It is the core region for photon generation, where electrons and holes recombine to generate photons. The lower confinement layer 21 and the upper confinement layer 23 restrict the vertical expansion of photons and charge carriers, ensuring that photons and charge carriers are concentrated in the quantum well active layer. The waveguide layer and the upper confinement layer 23 form a refractive index difference, guiding photon propagation and reducing light leakage.

[0060] Understandably, the materials and dimensions of the substrate 10, lower confinement layer 21, quantum well active layer, and ridge waveguide structure 30 can be adapted to actual needs.

[0061] In this embodiment, the substrate 10 needs to have good crystal quality and low defect density. In some embodiments, the substrate 10 layer is GaN (gallium nitride) or GaAs (gallium arsenide), and its thickness is between 200 nm and 3000 nm. The thickness of the substrate 10 can be any value between 200 nm, 3000 nm, and 200-3000 nm, such as 500 nm, 1000 nm, and 2000 nm.

[0062] In some embodiments, the material of the lower confinement layer 21 can be AlInGaN (Aluminum Indium Gallium Nitride) or AlGaAs (Aluminum Gallium Arsenide), and the thickness of the lower confinement layer 21 can be between 1-2 μm. The thickness of the lower confinement layer 21 can be 1 μm, 2 μm, and any value between 1-2 μm, such as 1.2 μm, 1.5 μm, 1.8 μm, and the like.

[0063] In some embodiments, the thickness of the quantum well active layer can be between 0.1-0.2 μm. The thickness of the quantum well active layer can be 0.1 μm, 0.2 μm, and any value between 0.1-0.2 μm, such as 0.12 μm, 0.15 μm, 0.18 μm, and the like. The material of the quantum well active layer can be AlGaAs (Aluminum Gallium Arsenide), or alternatively, AlInGaN (Aluminum Indium Gallium Nitride) well layer-AlInGaN (Aluminum Indium Gallium Nitride) barrier layer, or alternatively, InGaAs (Indium Gallium Arsenide) well layer-AlGaAs (Aluminum Gallium Arsenide) barrier layer.

[0064] In some embodiments, the material of the upper confinement layer 23 can be AlInGaN (Aluminum Indium Gallium Nitride) or AlGaAs (Aluminum Gallium Arsenide), and the thickness of the upper confinement layer 23 can be between 1-2 μm. The thickness of the upper confinement layer 23 can be 1 μm, 2 μm, and any value between 1-2 μm, such as 1.2 μm, 1.5 μm, 1.8 μm, and the like.

[0065] In the present embodiment, the ridge waveguide structure 30 can limit the expansion of the light field in the lateral direction, reduce the leakage of light, and improve the output quality and output power of the light beam. In some embodiments, the material of the ridge waveguide structure 30 is InGaP (Indium Gallium Phosphide), and the thickness of the ridge waveguide structure 30 can be between 250 nm-350 nm. The thickness of the ridge waveguide structure 30 can be 250 nm, 350 nm, and any value between 250-350 nm, such as 208 nm, 300 nm, and the like.

[0066] In one of the embodiments, the width of the ridge waveguide structure 30 can be between 7-9 μm. Specifically, by configuring the width of the ridge waveguide structure 30 to be between 7-9 μm, a wider ridge waveguide structure 30 can be formed. Since the width of the ridge waveguide structure 30 is larger, the resistance of the ridge waveguide structure 30 can be reduced, and the electro-optical conversion efficiency of the laser can be improved. Based on the structure of the sidewall photonic crystal 70, the high-order transverse mode can be effectively suppressed. Therefore, by using the wide ridge waveguide structure 30 of the present embodiment, the laser can suppress the high-order transverse mode while reducing the power consumption of the laser, and a high-power laser can be formed.

[0067] In this embodiment, the width of the ridge waveguide structure 30 is 8 μm. By setting the width of the ridge waveguide structure 30 to 8 μm, compared with the narrow ridge waveguide with a width of 3 μm, the resistance of the ridge waveguide structure 30 can be reduced by 40%, and the electro-optical conversion efficiency of the laser can be increased from 18% to 25%.

[0068] In some embodiments, a cap layer 31 is further disposed on the top of the ridge waveguide structure 30. One of the main functions of the cap layer 31 is current limiting. By designing a current-free region in the cap layer 31, current injection near the end face can be effectively reduced, thereby reducing end face overheating caused by non-radiative surface recombination and surface current. The cap layer 31 is made of GaAs (gallium arsenide) and its thickness is between 0.4 and 0.6 μm. The thickness of the cap layer 31 can be any value between 0.4 μm, 0.6 μm, and 0.4-0.6 μm, such as 0.45 μm, 0.5 μm, and 0.55 μm.

[0069] In some embodiments, the first electrode 40 and the second electrode 50 are the core structures for current injection. The first electrode 40 and the second electrode 50 are respectively connected to the P-type region and the N-type region of the chip to realize carrier injection so that the laser generating mechanism can generate laser.

[0070] In some embodiments, the first electrode 40 is a negative electrode plate, serving as the outlet of current, and can be made of metals such as titanium (Ti), aluminum (Al), or gold (Au). The second electrode 50 is a positive electrode plate, serving as the injection point of current, and can be made of metals such as titanium (Ti), platinum (Pt), or gold (Au).

[0071] In this embodiment, as Figure 2 As shown, the end-face photonic crystal 60 is disposed at the cavity surface end of the resonant cavity, forming at least a portion of the cavity surface. The end-face photonic crystal 60 indirectly suppresses higher-order longitudinal modes through reflectivity spatial distribution modulation. Specifically, the photonic crystal structure can increase the loss of higher-order longitudinal modes by introducing air holes or other low-refractive-index regions. Since the optical field distribution of higher-order longitudinal modes is more dispersed, these structures cause greater loss to higher-order longitudinal modes, thereby suppressing the lasing of higher-order longitudinal modes.

[0072] It can be understood that the etching of the end surface photonic crystal 60 should not exceed the quantum well active layer. If the etching depth of the end surface photonic crystal 60 exceeds the quantum well active layer, the integrity of the quantum well active layer will be damaged, the quantum well structure of the quantum well active layer will be damaged, the non-radiative recombination will be increased, and the light emitting efficiency and output power of the device will be reduced. In one embodiment, the etching depth of the end surface photonic crystal 60 is between 0.8-0.9 μm, and the thickness of the upper limiting layer 23 is between 1-2 μm, so the etching depth of the end surface photonic crystal 60 is less than the thickness of the upper limiting layer 23, and the end surface photonic crystal 60 will be limited in the upper limiting layer 23, so as to avoid damage to the quantum well active region 22 caused by etching of the photonic crystal.

[0073] In one embodiment, the photonic crystal period Λ1 of the end surface photonic crystal 60 is between 250-320 nm, and the photonic crystal duty cycle is between 0.3-0.4. Specifically, the photonic crystal period and the duty cycle affect the reflectivity of the fundamental mode. By controlling the photonic crystal period Λ1 of the end surface photonic crystal 60 to be between 250-320 nm and the photonic crystal duty cycle to be between 0.3-0.4, the reflectivity of the fundamental mode can be ensured to be greater than 85%, and the output quality of the laser can be improved.

[0074] In this embodiment, the end surface photonic crystal 60 is a double-period structure (Λ 11 =260 nm,Λ 12 =300 nm), and different period regions are selectively activated by current injection. The tuning speed can be improved, and the tuning response speed of the end surface photonic crystal 60 can be controlled to be less than 1 ms.

[0075] In this embodiment, the end surface photonic crystal 60 region integrates a micro-heating electrode (not labeled in the figure) with a width of 5 μm, and the effective refractive index (Δn=0.01-0.03) of the photonic crystal can be changed by local temperature regulation (ΔT=0-50℃), so that the wavelength can be tuned within a certain range, and the wavelength tuning range is ±3 nm.

[0076] In this embodiment, the end surface photonic crystal 60 adopts a duty cycle gradient design, and the duty cycle gradually changes from 0.3 to 0.4, thereby reducing the carrier localization effect and further optimizing the threshold current.

[0077] In one embodiment, the photonic crystal period Λ1 of the end-face photonic crystal 60 and the propagation constant β of the laser fundamental mode satisfy: β·Λ1=2π. Specifically, this condition is a concrete application of the Bragg diffraction principle in subwavelength photonic crystals, requiring that the propagation constant (β) of the end-face photonic crystal 60 period Λ1 and the laser fundamental mode satisfy wave vector matching β·Λ1=2π. When this condition is met, the fundamental mode light wave undergoes constructive interference in the end-face photonic crystal 60, maximizing the reflectivity (>85%); while the higher-order longitudinal modes, due to wave vector mismatch (β higher order ≠ 2π / Λ), experience a sharp drop in reflectivity to <5%, achieving longitudinal mode selective feedback.

[0078] In this embodiment, a subwavelength end-face photonic crystal 60 structure is integrated at the laser cavity end face. The photonic crystal period Λ1 of the end-face photonic crystal 60 structure is 250-320 nm, the duty cycle is 0.3-0.4, and the etching depth is between 0.8-0.9 μm. By using the phase matching condition (β·Λ1=2π), the fundamental mode reflectivity is greater than 85%, and the reflectivity of higher-order longitudinal modes is less than 5%, thereby achieving enhanced reflection of the fundamental mode and suppression of higher-order longitudinal modes.

[0079] In this embodiment, to enhance the suppression of higher-order transverse modes, such as Figure 3 As shown, the sidewall photonic crystal 70 should be placed as close as possible to the ridge waveguide structure 30. The sidewall photonic crystal 70 indirectly suppresses higher-order transverse modes through reflectivity spatial distribution modulation. Specifically, the fundamental mode optical field is concentrated at the center of the ridge waveguide, and is less affected by the sidewall photonic crystal 70, resulting in low loss. Higher-order transverse modes have high intensity in the sidewall photonic crystal 70, and are subjected to strong Bragg scattering due to the periodic scattering of the sidewall photonic crystal 70. The energy of the higher-order transverse modes leaks to the radiation mode, significantly increasing the loss, thereby effectively suppressing higher-order transverse modes.

[0080] Understandably, the etching of the sidewall photonic crystal 70 should be kept away from the quantum well active layer. If the etching depth of the end-face photonic crystal 60 exceeds the quantum well active layer, it will damage the integrity of the quantum well active layer, causing damage to the quantum well and other structures of the quantum well active layer, leading to increased non-radiative recombination, and thus reducing the luminous efficiency and output power of the device. In one embodiment, the etching depth of the sidewall photonic crystal 70 is within 0.8 μm. Based on the thickness of the upper confinement layer 23 being between 1 and 2 μm, the sidewall photonic crystal 70 is confined within the upper confinement layer 23, which can prevent the etching of the sidewall photonic crystal 70 from damaging the quantum well active region 22.

[0081] To increase the suppression effect of the sidewall photonic crystal 70 on the high-order transverse mode as much as possible, in one embodiment, the length of the sidewall photonic crystal 70 accounts for more than 80% of the length of the ridge waveguide structure 30. Specifically, by configuring the length of the sidewall photonic crystal 70 to account for more than 80% of the length of the ridge waveguide structure 30, the reconfigured light field distribution suppresses the high-order transverse mode, so that the sidewall photonic crystal 70 can effectively compensate for the mode control capability of the wide ridge waveguide structure 30.

[0082] In one embodiment, the distance between the sidewall photonic crystal 70 and the ridge waveguide structure 30 is within 100 nm. Specifically, based on the high intensity of the high-order transverse mode in the sidewall photonic crystal 70, by controlling the distance between the sidewall photonic crystal 70 and the ridge waveguide structure 30 to be within 100 nm, the sidewall photonic crystal 70 can be made as close to the ridge waveguide structure 30 as possible, so that the high-order transverse mode can be suppressed in the high-intensity region of the high-order transverse mode, and the suppression effect on the high-order transverse mode is improved.

[0083] In one embodiment, the distance between the etched bottom of the sidewall photonic crystal 70 and the quantum well active region 22 of the laser generation structure 20 is at least 20 nm. Specifically, by controlling the distance between the etched bottom of the sidewall photonic crystal 70 and the quantum well active region 22 to be more than 20 nm, the sidewall photonic crystal 70 can be isolated from the quantum well active region 22, and damage to the quantum well active region 22 by the sidewall photonic crystal 70 can be avoided.

[0084] In one embodiment, the photonic crystal period Λ2 of the sidewall photonic crystal 70 is between 250 nm and 320 nm. Specifically, by controlling the photonic crystal period Λ2 of the sidewall photonic crystal 70 to be between 250 nm and 320 nm, the fundamental mode reflectivity can be greater than 85%, the high-order transverse mode can be less than 5%, and the high-order transverse mode (TE 10 / TE 20 ) loss is much larger than the fundamental mode (TE 00 ), effectively suppressing the high-order transverse mode and improving the quality of laser output.

[0085] The embodiment of the present application also provides a forming process of a photonic crystal laser, as shown in Figure 4 , comprising the following steps:

[0086] S100: epitaxial growth is performed on the substrate 10 to form an epitaxial structure 80 having a ridge waveguide layer 30b;

[0087] S200: etching the periphery of the ridge waveguide layer 30b of the epitaxial structure 80 to obtain a laser generation structure 20 having a ridge waveguide structure 30, and forming a step 30a at the etched part;

[0088] S300: etching end facet photonic crystals 60 on both sides of the step 30a in the length direction, and etching side wall photonic crystals 70 on both sides of the step 30a in the width direction;

[0089] S400: depositing a first electrode 40 on the bottom of the substrate 10, and depositing a second electrode 50 on the top of the ridge waveguide structure 30.

[0090] Specifically, by the above process, the side wall photonic crystals 70 can be formed on both sides of the step 30a in the width direction, the end facet photonic crystals 60 can be formed on both sides of the step 30a in the length direction, the photonic crystal laser satisfying the suppression of high-order transverse modes and high-order longitudinal modes and the high-power laser output can be formed, and the generation cost of the laser is effectively controlled, and the yield of the laser is improved.

[0091] In one of the embodiments, epitaxial growth is performed on the substrate 10, as shown in the following. Figure 5 As shown, the formation of the epitaxial structure 80 with the ridge waveguide layer 30b includes: placing the substrate 10 in the growth chamber of the MOCVD (Metal-Organic Chemical Vapor Deposition) device, and sequentially growing the 1-2 μm thick n-type AlGaAs lower confinement layer 21, the 0.1-0.2 μm thick AlGaAs quantum well active region 22, the 1-2 μm thick p-type AlGaAs upper confinement layer 23, the 300 nm thick p-type InGaP waveguide layer 30b, and the 0.5 μm thick p-type GaAs cap layer 31, to obtain the epitaxial structure 80 of the photonic crystal laser.

[0092] In one of the embodiments, as shown in the following, etching the periphery of the ridge waveguide layer 30b of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30 includes: etching the periphery of the waveguide layer 30b and the cap layer 31 of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30, and the etching process includes photolithography, the photolithography process adopts 193 nm immersion photolithography, and the width of the obtained ridge waveguide structure 30 is 8 μm. Figure 6

[0093] In one of the embodiments, as shown in the following, etching the periphery of the ridge waveguide layer 30b of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30 includes: etching the periphery of the waveguide layer 30b and the cap layer 31 of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30, and the etching process includes photolithography, the photolithography process adopts 193 nm immersion photolithography, and the width of the obtained ridge waveguide structure 30 is 8 μm. Figure 7 In one of the embodiments, as shown in the following, etching the periphery of the ridge waveguide layer 30b of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30 includes: etching the periphery of the waveguide layer 30b and the cap layer 31 of the epitaxial structure 80 to obtain the laser generating structure 20 with the ridge waveguide structure 30, and the etching process includes photolithography, the photolithography process adopts 193 nm immersion photolithography, and the width of the obtained ridge waveguide structure 30 is 8 μm.

[0094] ​In one embodiment, such as Figure 8 As shown, etching to form sidewall photonic crystals 70 on both sides of the step 30a along its length includes: simultaneously etching a photonic crystal array with the same period and duty cycle between 0.3 and 0.4, and an etching depth of 0.8-0.9 μm at the two cavity ends of the resonant cavity using reactive ion etching (RIE) process, while maintaining the spacing between the sidewall photonic crystals 70 and the ridge waveguide structure 30 less than 100 nm.

[0095] In one embodiment, such as Figure 9 As shown, depositing a first electrode 40 at the bottom of the substrate 10 and a second electrode 50 at the top of the ridge waveguide structure 30 includes: depositing an N-type electrode (first electrode 40) at the bottom of the substrate 10 by a vapor deposition process, and depositing a P-type electrode (second electrode 50) at the top of the ridge waveguide structure 30 by a vapor deposition process.

[0096] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0097] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A photonic crystal laser, characterized by, The application relates to a laser device, comprising: a substrate; a laser generation structure arranged on the substrate; a ridge waveguide structure arranged on the laser generation structure away from the substrate, a step being formed between the ridge waveguide structure and the laser generation structure; a first electrode arranged on the substrate away from the laser generation structure; a second electrode arranged on the ridge waveguide structure away from the substrate; end-face photonic crystals etched on both sides of the step in the length direction of the step, used for suppressing high-order longitudinal modes of the laser generation structure, the photonic crystal period Lambda1 of the end-face photonic crystals being between 250 nm and 320 nm, the photonic crystal duty cycle being between 0.3 and 0.4, the photonic crystal period Lambda1 of the end-face photonic crystals and the propagation constant beta of the laser fundamental mode satisfying: beta*Lambda1=2pi; side-wall photonic crystals etched on both sides of the step in the width direction of the step, used for suppressing high-order transverse modes of the laser generation structure, the distance between the side-wall photonic crystals and the ridge waveguide structure being within 100 nm; the width of the ridge waveguide structure being between 7 and 9 microns.

2. The photonic crystal laser of claim 1, wherein, The length of the side-wall photonic crystals is more than 80% of the length of the ridge waveguide structure.

3. The photonic crystal laser of claim 1, wherein, The photonic crystal period Lambda2 of the side-wall photonic crystals is between 250 nm and 320 nm.

4. The photonic crystal laser of claim 1, wherein, The distance between the etched bottom of the side-wall photonic crystals and the quantum well active region of the laser generation structure is at least 20 nm.

5. The photonic crystal laser of claim 1, wherein, The laser generation structure comprises, from bottom to top, a lower confining layer, a quantum well active region and an upper confining layer, the ridge waveguide structure is formed on the upper confining layer and forms the step between the upper confining layer.

6. A forming process for a photonic crystal laser as claimed in claim 1, characterized by The application further relates to a method for manufacturing the laser device, comprising the following steps: epitaxial growth on a substrate to form an epitaxial structure with a ridge waveguide layer; etching the circumferential side of the ridge waveguide layer of the epitaxial structure to obtain a laser generation structure with a ridge waveguide structure and form a step at the etched position; etching end-face photonic crystals on both sides of the step in the length direction of the step and etching side-wall photonic crystals on both sides of the step in the width direction of the step; depositing a first electrode on the bottom of the substrate and depositing a second electrode on the top of the ridge waveguide structure.

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