A diffractive facet emitting semiconductor laser

Abstract

The application relates to a diffraction profile emitting semiconductor laser, which comprises, from top to bottom, an upper cladding layer, an upper waveguide layer, an active layer, a lower waveguide layer and a lower cladding layer, the active layer emits light when carriers are injected into the active layer, at least one side of the active layer is provided with an optical modulation structure, the optical modulation structure comprises a strong in-plane feedback region and a weak in-plane feedback region, the strong in-plane feedback region is located in a central region of the optical modulation structure, the weak in-plane feedback region is arranged around the strong in-plane feedback region, the radius of the strong in-plane feedback region is less than R1, the radius of the weak in-plane feedback region is less than R2, and R2 is greater than R1. The optical modulation layer of the semiconductor laser of the application comprises the strong in-plane feedback region with a radius less than R1 and the weak in-plane feedback region with a radius less than R2 and greater than R1, the structure can reduce the loss of the basic mode, increase the gain threshold difference between the basic mode and the high-order mode, and is beneficial to single-mode oscillation of large-size devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor lasers, in particular to a diffraction type surface emitting semiconductor laser. BACKGROUND

[0002] A periodic grating structure is made on a substrate material, with a period of a According to the Bragg diffraction condition, , λ is the wavelength of light, n eff is the effective refractive index, i is a positive integer, θ is the angle between the wave front and the grating plane. When a = λ / 2 n eff , it is a first-order grating, such as a distributed feedback laser (DFB), a distributed Bragg reflector (DBR), etc. When a = λ / n eff , it is a second-order grating, and the propagation direction of the scattered light is perpendicular to that of the incident light, which also satisfies the Bragg diffraction. Therefore, a second-order or higher grating can achieve surface emission.

[0003] Based on the wide stripe edge-emitting structure, a stripe grating is arranged in the stripe width direction to make a grating coupled surface emitting laser (GCSEL), such as document 1. In 2022, Kyoto University in Japan released a technical route for photonic crystal surface emitting laser (PCSEL) to achieve high-power single-mode output (document 2). The next year, they reported a PCSEL with a continuous output power of 50W, a divergence angle of less than 0.05°, and a brightness of 1GW / cm 2 ·sr. GCSEL and PCSEL are both horizontal cavity surface emitting structures, using a flat waveguide structure to limit the light field to a single mode in the z direction, and using a grating / photonic crystal structure to produce a z-direction diffraction component to achieve surface emission.

[0004] To achieve high-power and high-brightness laser output, the device area needs to be increased while maintaining single-mode output. For large-size devices, the in-plane feedback strength needs to be reduced, which will result in a smaller gain threshold difference between the fundamental mode and high-order modes, and even lower loss (i.e., gain threshold) of high-order modes.

[0005] Prior art documents:

[0006] Document 1: W. Pete Latham, Chandrasekhar Roychoudhuri, Jeff Bullington, High-Power Grating-Coupled Surface-Emitting Diode Lasers, Proc. SPIE 4594, 2001;

[0007] Document 2: Takuya Inoue, Masahiro Yoshida, John Gelleta, et al., General recipe to realize photonic-crystal surface-emitting lasers with 100-W-to-1-kW single-mode operation, Nature Communications, Vol. 13, 2022. SUMMARY

[0008] Therefore, it is necessary to provide a diffraction type surface emitting semiconductor laser to reduce the loss of the fundamental mode and increase the gain threshold difference between the fundamental mode and the high-order mode, which is conducive to single-mode lasing of large-size devices.

[0009] To solve the above technical problems, the technical solution adopted by the present application is:

[0010] A diffraction type surface emitting semiconductor laser, comprising, from top to bottom, an upper cladding layer, an upper waveguide layer, an active layer, a lower waveguide layer, and a lower cladding layer, wherein the active layer emits light when carriers are injected into the active layer, and at least one side of the active layer is provided with an optical modulation structure, the optical modulation structure comprising a strong in-plane feedback region and a weak in-plane feedback region, the strong in-plane feedback region being located in the central region of the optical modulation structure, and the weak in-plane feedback region being arranged around the strong in-plane feedback region, the radius of the strong in-plane feedback region being less than R1, the radius of the weak in-plane feedback region being less than R2, and R2 being greater than R1.

[0011] Preferably, the optical modulation structure is located in one or more of the upper cladding layer, the upper waveguide layer, the lower waveguide layer, and the lower cladding layer.

[0012] Preferably, the optical modulation structure is a ring-shaped grating structure or a ring-shaped air hole structure.

[0013] Preferably, the ring-shaped grating structure or the ring-shaped air hole structure adopts a second-order grating structure or a higher-order grating structure.

[0014] Preferably, the ring-shaped grating structure or the ring-shaped air hole structure is distributed in the radial direction according to the period of the Bessel function.

[0015] The Bessel function is of 0th or 1st order.

[0016] Preferably, the optical modulation structure is a ring grating structure, and is a 2nd order grating structure.

[0017] The duty cycle dc of the 2nd order grating structure is greater than 0.2 and less than 0.6, where dc = w / a, w is the groove width of the grating, and a is the period.

[0018] Preferably, the groove width of the grating in the strong in-plane feedback region is w1, and the groove width of the grating in the weak in-plane feedback region is w2, w2 > w1.

[0019] Preferably, the duty cycle dc1 of the strong in-plane feedback region is dc1 = w1 / a, and dc1 is greater than or equal to 0.25 and less than 0.5.

[0020] The duty cycle dc2 of the weak in-plane feedback region is dc2 = w2 / a, and dc2 is greater than or equal to 0.3 and less than 0.6.

[0021] Preferably, R1 is greater than 0.2*R2.

[0022] Preferably, no ring grating structure or ring air hole structure is arranged in a region with a radius less than 0.2*R2.

[0023] Preferably, R1 is greater than 0.3*R2.

[0024] Preferably, R1 is greater than 0.4*R2.

[0025] Preferably, the optical modulation structure is a ring air hole structure, and the shape of the air hole is one or more of a circle, an ellipse, a rectangle, a triangle, and a trapezoid.

[0026] Preferably, the shape of the air hole is an ellipse, where the short axis of the ellipse is in the radial direction of the ring air hole, and the long axis of the ellipse is in the tangential direction of the ring air hole.

[0027] Preferably, the ring air hole structure includes a first ring air hole and a second ring air hole, and the first ring air hole is larger than the second ring air hole.

[0028] The first ring air hole is distributed in the radial direction according to the period of the Bessel function, and the phase of adjacent two circles differs by 2π or an integer multiple of π greater than 2π.

[0029] The second ring air hole is distributed in the radial direction according to the period of the Bessel function, and the phase of adjacent two circles is consistent with that of the first ring air hole.

[0030] Preferably, in the strong in-plane feedback region, the phase of the second ring air hole and the nearest first ring air hole differs by π / 2; and in the weak in-plane feedback region, the phase of the second ring air hole and the nearest first ring air hole differs by π / 4.

[0031] Due to the adoption of the above technical solutions, the present application has the following advantages compared with the prior art:

[0032] The optical modulation layer of the semiconductor laser adopts a second-order or higher-order ring grating or ring air hole, and includes a strong in-plane feedback region with a radius less than R1 and a weak in-plane feedback region with a radius less than R2 and greater than R1. The structure can reduce the loss of the fundamental mode, while increasing the gain threshold difference between the fundamental mode and the high-order mode, which is beneficial to single-mode lasing of large-size devices. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the specification, and other drawings can also be obtained by those skilled in the art without creative labor.

[0034] Figure 1 A cross-sectional schematic diagram of a diffraction type surface emitting semiconductor laser structure provided by the present application;

[0035] Figure 2 A schematic diagram of a ring grating structure provided by the present application;

[0036] Figure 3 A schematic diagram of a ring air hole structure provided by the present application;

[0037] Among them, (a) is a schematic diagram of a ring air hole structure; (b) is a schematic diagram of a ring air hole structure with a phase difference of π / 2 between adjacent two circles; (c) is a schematic diagram of a ring air hole structure with a phase difference of π / 4 between adjacent two circles

[0038] Figure 4 A graph of several mode wavelengths and losses in embodiment 1 of the present application;

[0039] Figure 5 A graph of the relationship between different duty cycles dc1 and feedback coefficients in embodiment 1 of the present application;

[0040] Figure 6 A graph of the loss of mode A, the loss difference between mode B and mode A obtained by scanning dc1 and R1 in embodiment 1 of the present application;

[0041] Figure 7 A graph of the loss of mode A, the loss difference between mode B and mode A obtained by scanning dc1 and R1 in embodiment 2 of the present application;

[0042] Figure 8The loss of mode A, the loss difference between mode B and mode A obtained by scanning dc1 and R1 in the embodiment 3 of the present application are shown in the following figures:

[0043] Figure 9 The loss of mode A, the loss difference between mode B and mode A obtained by scanning dc1 and R1 in the embodiment 4 of the present application are shown in the following figures.

[0044] Wherein: 1, lower electrode; 2, lower cladding layer; 3, lower waveguide layer; 4, active layer; 5, upper waveguide layer; 6, upper cladding layer; 7, upper electrode; 8, optical modulation structure. DETAILED DESCRIPTION

[0045] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application can be practiced without some or all of these specific details, and that the present application is not limited to the specific embodiments disclosed below.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0047] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0048] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there can be a middle element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and the like used herein are only for the purpose of illustration and are not the only implementation.

[0049] The meaning of "a plurality" is two or more, unless otherwise expressly specified. " / " means "or" in the sense of the alternatives.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0051] At present, in order to realize high-power and high-brightness laser output, it is necessary to increase the device area and maintain single-mode output. For large-size devices, it is necessary to reduce the in-plane feedback strength, which will result in a smaller gain threshold difference between the fundamental mode and the high-order mode, and even a lower loss (i.e. gain threshold) of the high-order mode.

[0052] On this basis, the application provides a diffraction type surface emitting semiconductor laser, which comprises, from top to bottom, an upper cladding layer, an upper waveguide layer, an active layer, a lower waveguide layer and a lower cladding layer. When carriers are injected into the active layer, the active layer emits light. At least one side of the active layer is provided with an optical modulation structure. The optical modulation structure comprises a strong in-plane feedback region and a weak in-plane feedback region. The strong in-plane feedback region is located in the central region of the optical modulation structure, and the weak in-plane feedback region is arranged around the strong in-plane feedback region. The radius of the strong in-plane feedback region is less than R1, and the radius of the weak in-plane feedback region is less than R2, and R2 is greater than R1.

[0053] The optical modulation layer of the semiconductor laser of the application comprises a strong in-plane feedback region with a radius less than R1 and a weak in-plane feedback region with a radius less than R2 and greater than R1. This structure can reduce the loss of the fundamental mode and increase the gain threshold difference between the fundamental mode and the high-order mode, which is beneficial to single-mode lasing of large-size devices.

[0054] In some specific embodiments, the optical modulation structure is located on one side or both sides of the active layer, and can be located in one or more of the upper cladding layer, the upper waveguide layer, the lower waveguide layer and the lower cladding layer.

[0055] In some specific embodiments, the optical modulation structure can be a ring grating structure, as shown in FIG. 1, or a ring air hole structure, as shown in FIG. 2. Figure 2 Figure 3 In some specific embodiments, the optical modulation structure can be a ring grating structure, as shown in FIG. 1, or a ring air hole structure, as shown in FIG. 2.

[0056] The ring grating structure or the ring air hole structure comprises a strong in-plane feedback region and a weak in-plane feedback region. The strong in-plane feedback region is located in the central region and has a radius less than or equal to R1. The weak in-plane feedback region is arranged in the periphery and surrounds the strong in-plane feedback region, and has a radius greater than R1 and less than or equal to R2. ​

[0057] In some specific embodiments, the annular grating structure or the annular hole structure is distributed in the radial direction according to the period of the Bessel function of 0 order or 1 order.

[0058] In some specific embodiments, the annular grating structure or the annular hole structure adopts a two-order grating structure or a higher-order grating structure. Specifically, the annular grating structure or the annular hole structure can adopt a two-order grating structure, i.e., the phase difference between two adjacent circles is 2π, and the period a= λ / n eff , λ is the optical wavelength, n eff is the effective refractive index. The annular grating structure or the annular hole structure can adopt a three-order grating structure, i.e., the phase difference between two adjacent circles is 3π, and the period a=3 λ / 2 n eff . The annular grating structure or the annular hole structure can adopt a four-order grating structure, i.e., the phase difference between two adjacent circles is 4π, and the period a=2 λ / n eff . Among them, the period a1 of the annular grating structure or the annular hole structure in the strong in-plane feedback region and the period a2 of the annular grating structure or the annular hole structure in the weak in-plane feedback region are equal, both are a, or the corresponding wavelength λ is equal.

[0059] Preferably, the annular grating structure or the annular hole structure can adopt a two-order grating structure, i.e., the phase difference between two adjacent circles is 2π, and the period a= λ / n eff .

[0060] When the optical modulation structure is an annular grating structure, the in-plane feedback strength can be adjusted by adjusting the groove width w of the grating, i.e., the duty cycle dc, where dc=w / a, w is the groove width of the grating, and a is the period. Considering the limitations of the semiconductor laser epitaxial structure, patterning process, etching process and the like, preferably, dc is greater than 0.2 and less than 0.6.

[0061] In some specific embodiments, the groove width of the grating in the strong in-plane feedback region is w1, and the groove width of the grating in the weak in-plane feedback region is w2, w2>w1. The duty cycle dc1 of the strong in-plane feedback region is w1 / a, dc1 is greater than or equal to 0.25 and less than 0.5, and specifically dc1 can be 0.25, 0.3, 0.33, 0.37, 0.4, 0.42, 0.46, 0.48.

[0062] The duty cycle of the weak in-plane feedback region is dc2 = w2 / a, dc2 is greater than or equal to 0.3 and less than 0.6, and specifically, dc2 can be 0.3, 0.34, 0.37, 0.4, 0.43, 0.45, 0.49, 0.52, 0.55, 0.59.

[0063] In some specific embodiments, R1 is greater than 0.2*R2. In other specific embodiments, R1 can also be greater than 0.3*R2, and R1 is greater than 0.4*R2.

[0064] In some specific embodiments, no annular grating structure or annular hole structure is arranged in the region with a radius less than 0.2*R2.

[0065] When the optical modulation structure is an annular hole structure, the in-plane feedback strength can be adjusted by adjusting the shape and size of the hole.

[0066] In some specific embodiments, the shape of the hole is one or more of a circle, an ellipse, a rectangle, a triangle, and a trapezoid.

[0067] In some specific embodiments, the shape of the hole is an ellipse, wherein the short axis of the ellipse is in the radial direction of the annular hole, and the long axis of the ellipse is in the tangential direction of the annular hole.

[0068] In some specific embodiments, the shape of the hole is a rectangle, wherein the short side of the rectangle is in the radial direction of the annular hole, and the long side of the rectangle is in the tangential direction of the annular hole.

[0069] In some specific embodiments, the annular hole structure includes a first annular hole and a second annular hole, and the first annular hole is larger than the second annular hole.

[0070] The first annular hole is distributed in the radial direction according to the period of the Bessel function, and the phase difference between adjacent two circles is 2π or an integer multiple of π greater than 2π.

[0071] The second annular hole is distributed in the radial direction according to the period of the Bessel function, and the phase difference between adjacent two circles is consistent with that of the first annular hole.

[0072] In some specific embodiments, in the strong in-plane feedback region, the phase difference between the second annular hole and the nearest first annular hole is π / 2; in the weak in-plane feedback region, the phase difference between the second annular hole and the nearest first annular hole is π / 4, as shown in Figure 3

[0073] ​The optical modulation layer of the semiconductor laser of this invention employs a second-order or higher-order annular grating structure or annular aperture structure, including a strong in-plane feedback region with a radius smaller than R1 located in the central region and a weak in-plane feedback region with a radius smaller than R2 and larger than R1. The feedback coefficient of the strong in-plane feedback region is f1, and the feedback coefficient of the weak in-plane feedback region is f2, where f1 is greater than f2. This structure can reduce the loss of the fundamental mode while increasing the gain threshold difference between the fundamental mode and higher-order modes, which is beneficial for single-mode lasing of large-size devices.

[0074] The following is in conjunction with the appendix Figures 1-9 The present invention will be described in detail below with reference to specific embodiments.

[0075] Example 1

[0076] Taking GaN-based semiconductor lasers as an example, the following methods are employed: Figure 1 The epitaxial structure shown includes, from top to bottom, a lower electrode 1, a lower cladding layer 2, a lower waveguide layer 3, an active layer 4, an upper waveguide layer 5, an upper cladding layer 6, and an upper electrode 7. Depending on actual performance requirements, an electron blocking layer, a buffer layer, an ohmic contact layer, etc., can also be added. The above structure is a common structure and is not considered an inventive point of this invention; therefore, it will not be described in detail here.

[0077] In this embodiment, the optical modulation structure 8 is located in the upper cladding 6. The optical modulation structure 8 is a ring grating structure, and it is a second-order grating structure, that is, the phase difference between two adjacent rings is 2π, and the period a = λ / n eff , λ The wavelength of light n eff The effective refractive index is used. The annular grating structure is radially distributed according to a periodic distribution of a Bessel function, which is of order 0 or 1.

[0078] A ring-shaped grating structure is fabricated in the upper cladding 6, with a fixed device radius of 250 μm, i.e., R2 = 250 μm. The duty cycle of the grating within the weak-plane in-feedback region (radial region greater than R1 and less than R2) on the outer periphery is dc2 = 0.35; grating structures are present within the radius R1 of the strong-plane in-feedback region on the inner periphery. Figure 2 With R0=0, the duty cycle of the grating in the strong-plane feedback region is dc1=0.35. The design wavelength of 435 nm is calculated. By scanning different mode losses and frequencies near the design wavelength, the following results are obtained: Figure 4 .

[0079] Depend on Figure 4 It is known that the beam quality of mode A is better than that of mode B. Therefore, the structural design of this invention aims to minimize the loss of mode A while increasing the loss difference between mode A and mode B.

[0080] The duty cycle dcl of the grating in the strong in-plane feedback region is changed to obtain the feedback coefficient corresponding to the duty cycle of different gratings, as shown in Figure 5 . The greater the absolute value of the feedback coefficient, the stronger the in-plane feedback; the closer the absolute value of the feedback coefficient to 0, the weaker the in-plane feedback.

[0081] The duty cycle dc2 of the grating in the weak in-plane feedback region (the radial region is greater than R1 and less than R2) of the fixed periphery is 0.35. The radius R1 of the strong in-plane feedback region inside and the duty cycle dcl of the grating of the strong in-plane feedback region are adjusted respectively to scan the two parameters to obtain Figure 6 . Wherein, Figure 6 (a) in (a) represents the loss of mode A (i.e. gain threshold), Figure 6 (b) in (b) represents the loss of mode B minus the loss of mode A, that is, the difference in mode loss between the two. The greater the difference, the less likely mode B is to lase, and the better the device lasing mode can be stabilized in mode A to achieve single-mode output.

[0082] It can be known from Figure 6 that the structure of the embodiment sets the duty cycle dcl of the grating in the central region with a radius less than R1 as strong in-plane feedback, and sets the duty cycle dc2 of the grating in the peripheral region with a radius greater than R1 and less than R2 as weak in-plane feedback, which can reduce the loss of mode A and increase the loss difference between mode A and mode B.

[0083] Embodiment 2:

[0084] In this embodiment, a microcavity structure is added in the center of the annular grating structure, that is, no grating is arranged in the region with a radius less than R0, wherein R0 = 0.2 * R2, that is, no grating is arranged in the region with a radius less than 0.2 * R2, which can increase the loss difference between mode B and mode A.

[0085] An annular grating structure is made in the upper cladding layer 6, and the device size radius is fixed at 250 μm, that is, R2 = 250 μm. No grating structure is arranged in the region with a radius less than R0 = 50 μm in the center; the duty cycle dc2 of the grating in the weak in-plane feedback region (the radial region is greater than R1 and less than R2) of the fixed periphery is 0.35. The radius R1 of the strong in-plane feedback region inside and the duty cycle dcl of the grating of the strong in-plane feedback region are adjusted respectively to scan the two parameters to obtain Figure 7 . Wherein, Figure 7 (a) in (a) represents the loss of mode A (i.e. gain threshold), Figure 7 (b) in (b) represents the loss of mode B minus the loss of mode A, that is, the difference in mode loss between the two.

[0086] The other device structures of this embodiment are the same as those of embodiment 1.

[0087] From Figure 7 It can be seen that the gain threshold of the device of the embodiment is reduced, and the gain threshold difference between mode A and mode B is increased. Therefore, mode A is more likely to lase, and single-mode output can be maintained.

[0088] Embodiment 3:

[0089] The difference between the embodiment and embodiment 2 is that the device size radius is fixed at 500 μm, that is, R2=500 μm. No grating structure is arranged in the region with a center radius less than R0=100 μm; the duty cycle dc2=0.35 of the grating in the peripheral weak in-plane feedback region (the radial region is greater than R1 and less than R2) is fixed. The radius R1 of the internal strong in-plane feedback region and the duty cycle dc1 of the grating in the strong in-plane feedback region are adjusted respectively, and two parameters are scanned to obtain Figure 8 . Wherein, Figure 8 (a) in (a) represents the loss (that is, the gain threshold) of mode A, Figure 8 (b) in (b) represents the loss of mode B minus the loss of mode A, that is, the mode loss difference between the two.

[0090] The device structure of the embodiment is the same as that of embodiment 2.

[0091] From Figure 8 It can be seen that the gain threshold of the device of the embodiment is reduced, and the gain threshold difference between mode A and mode B is increased. Therefore, mode A is more likely to lase, and single-mode output can be maintained.

[0092] Embodiment 4:

[0093] The difference between the embodiment and embodiment 2 is that the device size radius is fixed at 750 μm, that is, R2=750 μm. No grating structure is arranged in the region with a center radius less than R0=150 μm; the duty cycle dc2=0.35 of the grating in the peripheral weak in-plane feedback region (the radial region is greater than R1 and less than R2) is fixed. The radius R1 of the internal strong in-plane feedback region and the duty cycle dc1 of the grating in the strong in-plane feedback region are adjusted respectively, and two parameters are scanned to obtain Figure 9 . Wherein, Figure 9 (a) in (a) represents the loss (that is, the gain threshold) of mode A, Figure 9 (b) in (b) represents the loss of mode B minus the loss of mode A, that is, the mode loss difference between the two.

[0094] The device structure of the embodiment is the same as that of embodiment 2.

[0095] By Figure 9 It can be seen that the gain threshold of the device of the embodiment is reduced, and the gain threshold difference between mode A and mode B is increased. Therefore, mode A is easier to lase, and single-mode output can be maintained.

[0096] The technical features of the above-described embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the description.

[0097] The above-described embodiments only express several implementation manners of the present application, the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A diffractive surface-emitting semiconductor laser, comprising, from top to bottom, an upper cladding layer, an upper waveguide layer, an active layer, a lower waveguide layer, and a lower cladding layer, wherein when charge carriers are injected into the active layer, the active layer emits light, characterized in that, At least one side of the active layer is provided with an optical modulation structure, the optical modulation structure includes a strong in-plane feedback region and a weak in-plane feedback region, the strong in-plane feedback region is located in the central region of the optical modulation structure, the weak in-plane feedback region is arranged around the strong in-plane feedback region, the radius of the strong in-plane feedback region is less than R1, the radius of the weak in-plane feedback region is less than R2, and R2 is greater than R1. The optical modulation structure is a ring grating structure or a ring aperture structure, and the ring grating structure or ring aperture structure adopts a second-order grating structure or a higher-order grating structure.

2. The diffraction-type surface-emitting semiconductor laser according to claim 1, characterized in that, The optical modulation structure is located in one or more of the upper cladding, upper waveguide, lower waveguide, and lower cladding layers.

3. The diffraction-type surface-emitting semiconductor laser according to claim 1, characterized in that, The annular grating structure or annular aperture structure is distributed radially according to the periodic distribution of the Bessel function; The Bessel function is of order 0 or 1.

4. The diffraction-type surface-emitting semiconductor laser according to claim 1, characterized in that, The duty cycle dc of the second-order grating structure is greater than 0.2 and less than 0.6, where dc = w / a, w is the groove width of the grating, and a is the period.

5. The diffraction-type surface-emitting semiconductor laser according to claim 4, characterized in that, The slot width of the grating in the strong plane feedback region is w1, and the slot width of the grating in the weak plane feedback region is w2, where w2 > w1.

6. The diffraction-type surface-emitting semiconductor laser according to claim 5, characterized in that, The duty cycle of the strong in-plane feedback region is dc1=w1 / a, where dc1 is greater than or equal to 0.25 and less than 0.

5. The duty cycle of the feedback region within the weak plane is dc2=w2 / a, where dc2 is greater than or equal to 0.3 and less than 0.

6.

7. The diffraction-type surface-emitting semiconductor laser according to claim 1, characterized in that, R1 is greater than 0.2*R2.

8. The diffraction-type surface-emitting semiconductor laser according to claim 7, characterized in that, No annular grating structures or annular aperture structures are set in areas with a radius less than 0.2*R2.

9. The diffraction-type surface-emitting semiconductor laser according to claim 7, characterized in that, R1 is greater than 0.3*R2.

10. The diffraction-type surface-emitting semiconductor laser according to claim 9, characterized in that, R1 is greater than 0.4*R2.

11. The diffraction-type surface-emitting semiconductor laser according to claim 1, characterized in that, The optical modulation structure is an annular aperture structure, and the shape of the aperture is one or more of the following: circular, elliptical, rectangular, triangular, and trapezoidal.

12. The diffraction-type surface-emitting semiconductor laser according to claim 11, characterized in that, The hole is elliptical in shape, wherein the minor axis of the ellipse is in the radial direction of the annular hole, and the major axis of the ellipse is in the tangential direction of the annular hole.

13. The diffraction-type surface-emitting semiconductor laser according to claim 11, characterized in that, The annular cavity structure includes a first annular cavity and a second annular cavity, wherein the first annular cavity is larger than the second annular cavity. The first annular hole is distributed radially according to the periodic distribution of the Bessel function, and the phase difference between two adjacent rings is 2π or an integer multiple of π greater than 2π; The second annular hole is distributed radially according to the periodic distribution of the Bessel function, and the phase of two adjacent rings is consistent with that of the first annular hole.

14. The diffraction-type surface-emitting semiconductor laser according to claim 13, characterized in that, In the strong-plane feedback region, the second annular hole is π / 2 out of phase with the nearest first annular hole; in the weak-plane feedback region, the second annular hole is π / 4 out of phase with the nearest first annular hole.

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