Laser and preparation method thereof

Abstract

The invention relates to the technical field of gratings, in particular to a laser and a preparation method thereof. The laser includes: a substrate; the grating layer is located on one side of the substrate and comprises a plurality of first refraction parts and second refraction parts which are alternately arranged and have different refractive indexes, the grating layer is provided with a first grating area and second grating areas, and the second grating areas are asymmetrically arranged on the two sides of the first grating area; a period formed by the first refraction part and the second refraction part in the first grating area is a first period, a period formed by the first refraction part and the second refraction part in the second grating area is a second period, and the first period is not equal to the second period. According to the invention, the second grating regions are asymmetrically arranged on the two sides of the first grating region, so that the propagation characteristic and phase distribution of a longitudinal mode in the grating layer are different, and the single-mode yield of the laser is enhanced. And the first grating area is internally provided with the first refraction part and the second refraction part, so that no peak appears in the first grating area.

Description

Technical Field

[0001] The present disclosure relates to the field of grating technology, and in particular to a laser and a preparation method thereof. Background Art

[0002] Distributed Feedback Laser (DFB) is mainly used to provide optical output with high monochromaticity and high side mode suppression ratio, and has been widely used in optical fiber communication systems.

[0003] In order to make the laser provide a more accurate and stable laser beam, the single-mode yield of DFB needs to be improved. However, in the related art, a uniform grating is built into the DFB, which makes the DFB have two longitudinal modes with the same lasing threshold, making it difficult for the DFB to control a certain longitudinal mode to be preferentially lased, which is not conducive to improving the single-mode yield of DFB. Summary of the invention

[0004] Based on this, it is necessary to provide a laser and a method for preparing the same in order to solve the problem of difficulty in improving the single-mode yield of lasers in the prior art.

[0005] In order to achieve the above object, on the one hand, a laser is provided, comprising:

[0006] substrate;

[0007] A grating layer is located on one side of the substrate, and includes a plurality of first refractive parts and second refractive parts which are alternately arranged and have different refractive indices. The grating layer has a first grating region and a second grating region. The second grating region is asymmetrically arranged on both sides of the first grating region. A period formed by the first refractive parts and the second refractive parts in the first grating region is a first period. A period formed by the first refractive parts and the second refractive parts in the second grating region is a second period. The first period is not equal to the second period.

[0008] In one embodiment, in a first direction, the length of the first refractive portion located in the first grating area is different from the length of the first refractive portion located in the second grating area, and / or the length of the second refractive portion located in the first grating area is different from the length of the second refractive portion located in the second grating area, and the first direction is the arrangement direction of the first refractive portion and the second refractive portion.

[0009] In one embodiment, the length of the first refractive portion located in the first grating region is greater than the length of the first refractive portion located in the second grating region, and / or the length of the second refractive portion located in the first grating region is greater than the length of the second refractive portion located in the second grating region.

[0010] In one embodiment, in a first direction, the first grating region has a first length, and the first period and the first length satisfy:

[0011] P=Lp / Λ-Lp / Λ0=0.5±n, wherein P is the target phase of the grating layer, Lp is the first length, Λ is the first period, Λ0 is the second period, and n is 0 or a positive integer.

[0012] In one embodiment, n is greater than or equal to 1.

[0013] In one embodiment, the second grating region has a second length, the sum of the first length and the second length is the length of the grating layer, and the ratio of the first length to the length of the grating layer is in the range of 0.1-0.3.

[0014] In one embodiment, the first refractive portion and the second refractive portion have the same doping type.

[0015] In one embodiment, the refractive index of the first refractive portion is lower than the refractive index of the second refractive portion, the material of the first refractive portion includes InP, and the material of the second refractive portion includes P-InGaAsP.

[0016] In one aspect, a method for preparing a laser is provided, comprising:

[0017] providing a substrate;

[0018] A grating layer is formed on one side of the substrate, the grating layer includes a plurality of first refractive parts and second refractive parts which are alternately arranged and have different refractive indices, the grating layer has a first grating region and a second grating region, the second grating region is asymmetrically arranged on both sides of the first grating region, a period formed by the first refractive parts and the second refractive parts in the first grating region is a first period, a period formed by the first refractive parts and the second refractive parts in the second grating region is a second period, and the first period is not equal to the second period.

[0019] In one embodiment, forming a grating layer on one side of the substrate includes:

[0020] forming a grating material layer on one side of the substrate;

[0021] Patterning the grating material layer to form a plurality of grooves, with the first refractive parts formed on both sides of the grooves;

[0022] The groove is filled to form the second refractive portion.

[0023] The laser of the present application and its preparation method have the following beneficial effects: First, the application sets the second grating area to be asymmetrically arranged on both sides of the first grating area, so that the propagation characteristics and phase distribution of the longitudinal mode in the grating layer are different. This difference causes the longitudinal mode that can be propagated in the grating to change in optical characteristics such as reflection and transmission. At this time, a stably transmitted longitudinal mode is generated at the center of the two equivalent longitudinal modes in the prior art, and has a very strong feedback effect, thereby reducing its lasing threshold, while the two longitudinal modes in the prior art are difficult to lasing due to the weakening of the feedback effect. Therefore, the laser of the present application enhances the single-mode yield of the laser. Secondly, in the present application, it is also provided that the first grating area is provided with a plurality of first refractive parts and second refractive parts that are alternately arranged and have different refractive indices, thereby dispersing the light intensity in the first grating area, so that no peaks appear in the first grating area, thereby reducing the possibility of spatial hole burning in the first grating area. Finally, the present application can flexibly adjust the first length, the first period and the second period, so that the target phase P target value of the grating layer can be set to 1.5, 2.5, 3.5..., thereby reducing the difficulty of preparing the first grating area and the second grating area. On the basis of the above, the P range value is set to 1.5±0.1, 2.5±0.1, 3.5±0.1, etc. During the secondary etching alignment, this embodiment increases the tolerance of the alignment error generated at the interface between the first grating area and the second grating area, and reduces the probability of phase deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 is a schematic diagram of a laser provided in an embodiment;

[0026] Figure 2 is a schematic diagram of a grating layer provided in an embodiment;

[0027] Figure 3 Schematic diagram of related technology;

[0028] Figure 4 A schematic diagram of a laser preparation method provided in an embodiment;

[0029] Figure 5 is a schematic diagram of a substrate provided in an embodiment;

[0030] Figure 6 A schematic diagram of a groove provided in an embodiment;

[0031] Figure 7 A schematic diagram of a laser provided in another embodiment;

[0032] Figure 8 is a schematic diagram of a ridge waveguide structure provided in an embodiment;

[0033] Fig. 9 is a flow chart of a method for preparing a grating layer provided in an embodiment;

[0034] Fig.10 A flow chart of a film preparation method provided in an embodiment;

[0035] Fig.11 The present invention is a flow chart of a film preparation method provided in another embodiment.

[0036] Explanation of the reference numerals: laser-100; substrate-110; grating layer-120; grating material layer-1200; first refractive portion-121; second refractive portion-122; first grating region-123; second grating region-124; first semiconductor layer-130; active layer-131; second semiconductor layer-132; third semiconductor layer-133; third semiconductor material layer-1330; third semiconductor intermediate layer-1331; fourth semiconductor layer-134; electrode contact layer-135; dielectric layer-136; N-type electrode layer-137; P-type electrode layer-138; ridge waveguide structure-139; groove-200.

[0037] In order to better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the embodiments and / or examples currently described, and the best modes of these inventions currently understood. DETAILED DESCRIPTION

[0038] In order to facilitate understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure.

[0040] In each embodiment, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in each embodiment can be understood according to the specific situation.

[0041] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" other elements or layers, it can be directly on, adjacent to, connected to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers, doping types and / or parts, these elements, components, regions, layers, doping types and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or part from another element, component, region, layer, doping type or part. Therefore, without departing from the teaching of the present embodiment, the first element, component, region, layer, doping type or part discussed below can be represented as a second element, component, region, layer, doping type or part.

[0042] Spatial relationship terms such as "under", "below", "below", "under", "above", "above", etc., may be used herein to describe the relationship between an element or feature shown in the figures and other elements or features. It should be understood that in addition to the orientations shown in the figures, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, the element or feature described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0043] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that when the terms "consisting of" and / or "comprising" are used in this specification, the presence of the features, integers, steps, operations, elements and / or parts can be determined, but the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups is not excluded. At the same time, when used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0044] Embodiments of the present specification are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments (and intermediate structures) of the present specification, and variations from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are anticipated. Thus, embodiments of the present specification should not be limited to the particular shapes of the regions illustrated herein, but rather include deviations in shapes due to, for example, manufacturing techniques. The regions shown in the figures are schematic in nature, and their shapes do not represent the actual shapes of the regions of the device, and do not limit the scope of the embodiments of the present specification.

[0045] See also Figure 1 and Figure 2 This embodiment provides a laser 100 including a substrate 110 and a grating layer 120 .

[0046] The substrate 110 may be conductive so as to conduct current for other film layers of the laser 100. For example, the material of the substrate 110 may include InP or the like.

[0047] The grating layer 120 may be located on one side of the substrate 110. For example, the thickness of the grating layer 120 may be in the range of 100 nm to 200 nm. The above data are only used as examples, and in actual embodiments, the thickness of the grating layer 120 is not limited to the above data.

[0048] See also Figure 2 , the grating layer 120 may include a plurality of first refractive portions 121 and second refractive portions 122 that are alternately arranged and have different refractive indices. For example, the first refractive portion 121 may have a low refractive index, and the second refractive portion 122 may have a high refractive index. The doping ion type of the first refractive portion 121 and the second refractive portion 122 is the same, for example, the doping type of the first refractive portion 121 and the second refractive portion 122 may both be P-type. Specifically, the material of the first refractive portion 121 may include P-InP, etc., and the material of the second refractive portion 122 may include P-InGaAsP, etc. This embodiment does not specifically limit the doping ions.

[0049] Also, see Figure 2, the grating layer 120 has a first grating region 123 and a second grating region 124. The first grating region 123 is located in the second grating region 124, and the second grating region 124 is asymmetrically arranged on both sides of the first grating region 123. This embodiment does not specifically limit the size, distribution, etc. of the first grating region 123 and the second grating region 124. It can be understood that a plurality of first refractive portions 121 and second refractive portions 122 that are alternately arranged and have different refractive indices are provided in the first grating region 123 and the second grating region 124.

[0050] The first refractive portion 121 and the second refractive portion 122 in the first grating area 123 form a first period, and form a second period with the first refractive portion 121 and the second refractive portion 122 in the second grating area 124. The first period is different from the second period. For example, in the first direction, the first grating area 123 has a first length, the first grating area 123 has a first period, and the first period and the first length satisfy:

[0051] P=Lp / Λ-Lp / Λ0=0.5+n, (n≥1);

[0052] P=Lp / Λ-Lp / Λ0=-0.5-n, (n≥1).

[0053] Wherein, P is the target phase of the grating layer 120, Lp is the first length, Λ is the first period, Λ0 is the second period of the second grating region 124, and n is 0 and a positive integer.

[0054] In addition, the grating layer 120 needs to satisfy the grating equation:

[0055] λ = Λ0 / 2Neff;

[0056] Wherein, Λ is the second period, Neff is the effective refractive index of the laser 100, and λ is the designed lasing wavelength.

[0057] As an example, the P target value can be set to ±1.5, ±2.5, ±3.5, etc. On the basis of the above, the P value range is set to ±1.5±0.1, ±2.5±0.1, ±3.5±0.1, etc. When the target phase (P value) is 0.5, when the first refraction portion 121 in the first grating area 123 and the second grating area 124 are formed respectively, the preparation of the film layer is more difficult due to the smaller difference in the grating period (that is, it is more difficult for the equipment to distinguish the difference between the periods). Specifically, in this process, the second refraction portion 122 in the second grating area 124 can be first formed on the substrate 110, and the area of ​​the first grating area 123 is reserved, and then the second refraction portion 122 in the first grating area 123 is formed. When the target phase of the grating layer 120 is 0.5, it is difficult to control the length of the second refraction portion 122 at the junction of the first grating area 123 and the second grating area 124 in the actual process. Furthermore, in this embodiment, n can be set to be greater than or equal to 1, that is, the P value is set to ±1.5, ±2.5, ±3.5, etc., which increases the difference in grating period between the first grating area 123 and the second grating area 124, thereby reducing the difficulty of distinguishing different grating period patterns when preparing the grating preparation equipment, and on the basis of the above, the P value range is set to 1.5±0.1, 2.5±0.1, 3.5±0.1, etc., so that the allowable error at the junction of the first grating area 123 and the second grating area 124 becomes larger, thereby reducing the requirements for grating accuracy in forming the first grating area 123 and the second grating area 124, thereby reducing the difficulty of preparation. Further, in this embodiment, the target P value can be obtained by adjusting the first period, the first length and the second period. In one possible example, when the first length is a fixed value, the absolute value of the difference between the first period and the second period (∆Λ=|Λ-Λ0|) can be increased to obtain the target P value. In another possible example, when the first period and the second period are fixed values, the target P value can be obtained by adjusting the first length.

[0058] The second grating region 124 may have a second length, and the sum of the first length and the second length may be the length of the grating layer 120. The ratio of the first length to the length of the grating layer 120 may be in the range of 0.1-0.3. As an example, in the ratio of the first length to the length of the grating layer 120, the first length is used as a numerator, and the sum of the first length and the second length (the length of the grating layer 120) is used as a denominator. For example, the ratio of the first length to the length of the grating layer 120 may be 0.2. This embodiment does not limit the specific lengths of the first grating region 123 and the second grating region 124.

[0059] See also Figure 3 In the related art, the first refractive portion 12A and the second refractive portion 12B of the grating 12 are arranged evenly, but this makes it difficult for the laser to obtain a high single-mode yield.

[0060] In this embodiment, firstly, the second grating region 124 is asymmetrically arranged on both sides of the first grating region 123, so that the propagation characteristics and phase distribution of the longitudinal mode in the grating layer are different. This difference causes the longitudinal mode that can propagate in the grating to change in optical characteristics such as reflection and transmission. At this time, a longitudinal mode that can be stably transmitted is generated at the center of the two equivalent longitudinal modes in the prior art, and has a very strong feedback effect, thereby reducing its lasing threshold; while the two longitudinal modes in the prior art are difficult to lasing due to the weakening of the feedback effect. Therefore, this embodiment enhances the single-mode yield of the laser 100. Secondly, in this embodiment, a plurality of first refractive portions 121 and second refractive portions 122 that are alternately arranged and have different refractive indices are also arranged in the first grating region 123, thereby dispersing the light intensity in the first grating region 123, so that no peaks appear in the first grating region 123, thereby reducing the possibility of spatial hole burning in the first grating region 123. Finally, the present embodiment can flexibly adjust the first length, the first period and the second period to set the P value to 1.5, 2.5, 3.5, ..., which increases the difference in grating period between the first grating area 123 and the second grating area 124, thereby reducing the difficulty of distinguishing different grating period patterns when preparing the grating preparation equipment, and on the basis of the above, the P value range is set to 1.5±0.1, 2.5±0.1, 3.5±0.1, etc., so that the allowable error at the junction of the first grating area 123 and the second grating area 124 becomes larger, thereby reducing the requirements for grating accuracy in forming the first grating area 123 and the second grating area 124, thereby reducing the difficulty of preparation.

[0061] In one embodiment, see Figure 2 In the first direction, the length of the first refractive portion 121 located in the first grating area 123 is different from the length of the first refractive portion 121 located in the second grating area 124, and / or the length of the second refractive portion 122 located in the first grating area 123 is different from the length of the second refractive portion 122 located in the second grating area 124.

[0062] As an example, the first direction may be Figure 2In one possible example, the length of the first refractive portion 121 in the first grating area 123 is greater than the length of the first refractive portion 121 in the second grating area 124. In another possible example, the length of the second refractive portion 122 in the first grating area 123 is greater than the length of the second refractive portion 122 in the second grating area 124. Of course, in yet another possible example, the length of the first refractive portion 121 in the first grating area 123 may also be less than the length of the first refractive portion 121 in the second grating area 124, and / or the length of the second refractive portion 122 in the first grating area 123 may also be less than the length of the second refractive portion 122 in the second grating area 124.

[0063] In this embodiment, by controlling the lengths of the first refractive portion 121 and / or the second refractive portion 122 in different regions, the period of the first grating region 123 can be accurately controlled to be different from the period of the second grating region 124. Moreover, when the length of the second refractive portion 122 in the first grating region 123 is greater than the length of the second refractive portion 122 in the second grating region 124, the difficulty of preparing the second refractive portion 122 in the first grating region 123 can also be reduced.

[0064] See also Figures 5 to 8 In addition, the laser 100 may further include a first semiconductor layer 130 , an active layer 131 , a second semiconductor layer 132 , a third semiconductor layer 133 , a fourth semiconductor layer 134 , an electrode contact layer 135 , a dielectric layer 136 , an N-type electrode layer 137 , and a P-type electrode layer 138 .

[0065] The first semiconductor layer 130 may be located on a side of the substrate 110 facing the grating layer 120. The doping ion type of the first semiconductor layer 130 may be N-type. For example, the material of the first semiconductor layer 130 may include N-type InP, etc. The thickness of the first semiconductor layer 130 may be in the range of 50nm-400nm. The above data are only used as examples, and the thickness of the first semiconductor layer 130 in actual embodiments is not limited to the above data.

[0066] The active layer 131 may be located on a side of the first semiconductor layer 130 away from the substrate 110. The active layer 131 may not be doped. For example, the material of the active layer 131 may include InAlGaAs or InGaAsP. Further, the active layer 131 may include a quantum well layer and an upper confinement layer and a lower confinement layer located on opposite sides of the quantum well layer. The lower confinement layer may be located between the quantum well layer and the first semiconductor layer 130.

[0067] The second semiconductor layer 132 may be located on the side of the active layer 131 away from the first semiconductor layer 130. The doping type of the second semiconductor layer 132 may be P-type. The material of the second semiconductor layer 132 may include P-type InP, etc. The thickness of the second semiconductor layer 132 may be in the range of 50nm-200nm. The above data are only used as examples, and the thickness of the second semiconductor layer 132 in actual embodiments is not limited to the above data.

[0068] The third semiconductor layer 133 may be located on a side of the grating layer 120 away from the second semiconductor layer 132. The doping type of the third semiconductor layer 133 may be P-type. Further, the doping concentration of the third semiconductor layer 133 may be greater than the doping concentration of the grating layer 120. The material of the third semiconductor layer 133 may be the same as the material of the first refractive portion 121. That is, the material of the third semiconductor layer 133 may also include P-type InP, etc. The thickness of the third semiconductor layer 133 may be in the range of 10nm-100nm. The above data are only used as examples, and the thickness of the third semiconductor layer 133 in actual embodiments is not limited to the above data.

[0069] The fourth semiconductor layer 134 may be located on a side of the third semiconductor layer 133 away from the grating layer 120, and the doping type of the fourth semiconductor layer 134 may be P-type. The material of the fourth semiconductor layer 134 may include P-type InP, etc. The doping concentration of the fourth semiconductor layer 134 may be greater than the doping concentration of the third semiconductor layer 133. The thickness of the fourth semiconductor layer 134 is greater than or equal to 1.5 μm. The above data are only used as examples, and the thickness of the third semiconductor layer 133 in actual embodiments is not limited to the above data.

[0070] The electrode contact layer 135 may be located on a side of the fourth semiconductor layer 134 away from the third semiconductor layer, and the doping type of the electrode contact layer 135 may be P-type. The material of the electrode contact layer 135 includes heavily doped P-InGaAsP and P-InGaAs, etc. The doping concentration of the electrode contact layer 135 may be greater than the doping concentration of the fourth semiconductor layer 134, and the thickness of the electrode contact layer 135 may be in the range of 200nm-500nm.

[0071] In addition, the third semiconductor layer 133, the fourth semiconductor layer 134, and the electrode contact layer 135 may only cover part of the grating layer 120. In this case, the third semiconductor layer 133, the fourth semiconductor layer 134, and the electrode contact layer 135 may form a protrusion protruding along the thickness direction of the laser 100, and the protrusion may constitute a ridge waveguide structure 139. The ridge waveguide structure 139 may cover a part of the grating layer 120. For example, the ridge waveguide structure 139 may extend along the second direction (for example, the Y direction), and the second direction may intersect with the first direction, for example, the second direction may be perpendicular to the first direction. In this case, the ridge waveguide structure 139 may at least cover the first grating region 123, or the ridge waveguide structure 139 may cover both the first grating region 123 and the second grating region 124.

[0072] The dielectric layer 136 may cover the sidewalls of the ridge waveguide structure 139 and the surface of the grating layer 120 not covered by the ridge waveguide structure 139. The material of the dielectric layer 136 may include SiO2 or Si3N4.

[0073] The N-type electrode layer 137 may be located on a side of the substrate 110 away from the first semiconductor layer 130. The P-type electrode layer 138 may be located on a side of the ridge waveguide structure 139 away from the grating layer 120 of the substrate 110. The materials of the N-type electrode layer 137 and the P-type electrode layer 138 are metal materials. At this time, the substrate 110 needs to conduct the current to conduct the two electrode layers, so the impedance of the substrate 110 can be reduced by heavy doping to achieve better ohmic contact. The present application does not specifically limit the P-type impurity ions and the N-type impurity ions. For example, the P-type impurity ions may include but are not limited to any one or more of zinc (Zinc, Zn), carbon (Carbon, C), or magnesium (Magnesium, Mg) ions, etc., and the N-type impurity ions may include but are not limited to one or more of silicon (Silicon, Si), sulfur (Sulphur, S) ions, and tellurium (Tellurium, Te) ions.

[0074] Based on the same inventive concept, in one embodiment, please refer to Figure 4 , a method for preparing a laser 100 is provided, comprising the following steps:

[0075] Step S100: providing a substrate 110 .

[0076] Step S300: forming a grating layer 120 on one side of the substrate 110, the grating layer 120 comprising a plurality of first refractive portions 121 and second refractive portions 122 which are alternately arranged and have different refractive indices, the grating layer 120 having a first grating region 123 and a second grating region 124, the second grating region 124 being asymmetrically arranged on both sides of the first grating region 123, a period formed by the first refractive portions 121 and the second refractive portions 122 in the first grating region 123 being a first period, a period formed by the first refractive portions 121 and the second refractive portions 122 in the second grating region 124 being a second period, and the first period is not equal to the second period.

[0077] In step S100, the substrate 110 may have electrical conductivity so as to conduct current for other film layers of the laser 100. For example, the material of the substrate 110 may include InP or the like.

[0078] In step S300, specifically, the first refractive portion 121 may have a low refractive index, and the second refractive portion 122 may have a high refractive index. The doping ion type of the first refractive portion 121 and the second refractive portion 122 is the same, for example, the doping type of the first refractive portion 121 and the second refractive portion 122 may both be P-type. Specifically, the material of the first refractive portion 121 may include InP, etc., and the material of the second refractive portion 122 may include P-InGaAsP, etc.

[0079] The first grating area 123 is located in the second grating area 124, and the second grating area 124 is asymmetrically disposed on both sides of the first grating area 123. At this time, a plurality of first refractive portions 121 and second refractive portions 122 are alternately disposed and have different refractive indices in the first grating area 123 and the second grating area 124.

[0080] The period of the first grating region 123 is different from the period of the second grating region 124. For example, in the first direction, the first grating region 123 has a first length, the first grating region 123 has a first period, and the first period and the first length satisfy:

[0081] P=Lp / Λ-Lp / Λ0=0.5+n, (n≥1);

[0082] P=Lp / Λ-Lp / Λ0=-0.5-n, (n≥1).

[0083] Wherein, P is the target phase of the grating layer 120, Lp is the first length, Λ is the first period, Λ0 is the second period of the second grating region 124, and n is 0 and a positive integer.

[0084] As an example, the P value may be set to 1.5, 2.5, 3.5, etc. In this embodiment, the target P value may be obtained by adjusting the first length, or adjusting the first period and the second period.

[0085] In this embodiment, firstly, the second grating region 124 is asymmetrically arranged on both sides of the first grating region 123, so that the propagation characteristics and phase distribution of the longitudinal mode in the grating layer are different. This difference causes the longitudinal mode that can propagate in the grating to change in optical characteristics such as reflection and transmission. At this time, a longitudinal mode that can be stably transmitted is generated at the center of the two equivalent longitudinal modes in the prior art, and has a very strong feedback effect, thereby reducing its lasing threshold; while the two longitudinal modes in the prior art are difficult to lasing due to the weakening of the feedback effect. Therefore, this embodiment enhances the single-mode yield of the laser 100. Secondly, in this embodiment, a plurality of first refractive portions 121 and second refractive portions 122 that are alternately arranged and have different refractive indices are also arranged in the first grating region 123, thereby dispersing the light intensity in the first grating region 123, so that no peaks appear in the first grating region 123, thereby reducing the possibility of spatial hole burning in the first grating region 123. Finally, the present embodiment can flexibly adjust the first length, the first period and the second period, so that the target phase P value of the grating layer 120 can be set to 1.5, 2.5, 3.5, ..., which makes the difference between the grating period of the first grating area 123 and the second grating area 124 larger, thereby reducing the difficulty of distinguishing different grating period patterns when preparing the grating preparation equipment, and on the basis of the above, the P value range is set to 1.5±0.1, 2.5±0.1, 3.5±0.1, etc., so that the allowable error at the junction of the first grating area 123 and the second grating area 124 becomes larger, thereby reducing the requirements for grating accuracy in forming the first grating area 123 and the second grating area 124, thereby reducing the difficulty of preparation.

[0086] Specifically, Fig. 9 , step S300 includes:

[0087] Step S310 : forming a grating material layer 1200 on one side of the substrate 110 .

[0088] Step S320 : patterning the grating material layer 1200 to form a plurality of grooves 200 , and forming first refractive portions 121 on both sides of the grooves 200 .

[0089] Step S330 : filling the groove 200 to form the second refractive portion 122 .

[0090] In step S310 to step S330, a patterned mask layer may be formed on a side of the grating material layer 1200 away from the substrate 110, and then the grating material layer 1200 may be etched based on the patterned mask layer to form a plurality of grooves 200. For example, the etching may be dry etching or wet etching. The dry etching may include at least any one of reactive ion etching, inductively coupled plasma etching or high concentration plasma etching. Afterwards, the second refractive portion 122 is formed by filling the grooves 200.

[0091] In a possible example, in step S320, the process may be performed in steps. For example, at this time, the second refractive portion 122 located in the second grating region 124 may be formed first, and the grating material layer 1200 located in the first grating region 123 may be retained. Afterwards, the grating material layer 1200 located in the first grating region 123 may be aligned and etched to form the second refractive portion 122 located in the first grating region 123. It is understood that the length of the second refractive portion 122 in the first grating region 123 may be different from the length of the second refractive portion 122 in the second grating region 124, and a more accurate length of the first refractive portion 121 may be obtained by etching in steps (secondary etching). Moreover, during the secondary etching alignment, the P value is set to 1.5, 2.5, 3.5, etc., which increases the difference in grating period between the first grating area 123 and the second grating area 124, thereby reducing the difficulty of distinguishing different grating period patterns when the grating preparation equipment is prepared. On the basis of the above, the P value range is set to 1.5±0.1, 2.5±0.1, 3.5±0.1, etc., so that the allowable error at the junction of the first grating area 123 and the second grating area 124 becomes larger, thereby reducing the requirements for grating accuracy in forming the first grating area 123 and the second grating area 124, thereby reducing the difficulty of preparation.

[0092] In another possible example, see Figure 5 , after forming the grating material layer 1200, a third semiconductor material layer 1330 may be formed. Then, a photoresist layer may be formed on a side of the third semiconductor material layer 1330 away from the grating material layer 1200, and an electron beam exposure may be used to form a patterned photoresist layer. Figure 6 , the third semiconductor material layer 1330 and the grating material layer 1200 are sequentially etched using a patterned photoresist layer to form a groove 200 extending from the third semiconductor material layer 1330 to the grating material layer 1200. Alternatively, the third semiconductor material layer 1330 may be etched first to form a third semiconductor intermediate layer 1331, and the third semiconductor intermediate layer 1331 is used as a mask layer to etch the grating material layer 1200. Then, please refer to Figure 7 When the trench 200 is filled, the portion between the adjacent first refraction portions 121 forms the second refraction portion 122, and the portion in the third semiconductor intermediate layer 1331 and the third semiconductor intermediate layer 1331 form the third semiconductor layer 133. At this time, the material of the third semiconductor layer 133 is consistent with the material of the second refraction portion 122. Alternatively, when the trench 200 is filled, epitaxial growth can also be performed to form the fourth semiconductor layer 134, etc.

[0093] In this embodiment, the groove 200 and the first refractive portion 121 are formed by patterning the grating material layer 1200 , thereby facilitating the preparation of the second refractive portion 122 and improving the preparation efficiency.

[0094] Also, see Fig.10 Before step S300, the following steps may also be included:

[0095] Step S200 : forming a first semiconductor layer 130 on one side of the substrate 110 .

[0096] Step S210 : forming an active layer 131 on a side of the first semiconductor layer 130 away from the substrate 110 .

[0097] Step S220 : forming a second semiconductor layer 132 on a side of the active layer 131 away from the first semiconductor layer 130 .

[0098] And, after step S300, please refer to Fig.11 ,include:

[0099] Step S400 : forming a ridge waveguide structure on a side of the grating layer 120 away from the second semiconductor layer 132 , wherein the ridge waveguide structure includes a third semiconductor layer 133 away from the grating layer 120 , a fourth semiconductor layer 134 , and an electrode contact layer 135 .

[0100] Step S410 : forming a dielectric layer 136 on the sidewalls of the ridge waveguide structure 139 and the surface of the grating layer 120 not covered by the ridge waveguide structure 139 , wherein the dielectric layer 136 at least partially exposes the electrode contact layer 135 .

[0101] Step S420 : forming a P-type electrode layer 138 on the side of the electrode contact layer 135 exposed by the dielectric layer 136 .

[0102] Step S430 : thinning the substrate 110 , and forming an N-type electrode layer 137 on a side of the substrate 110 away from the active layer 131 .

[0103] In step S200, refer to Figure 5 The first semiconductor layer 130 can be used as a growth buffer layer, and the first semiconductor layer 130 can be made of the same material as the substrate 110. The doping concentration of the first semiconductor layer 130 can be lower than that of the substrate 110, thereby reducing the light loss caused by doping ions, and can also shield and block the defects generated during the initial growth of the first semiconductor layer 130, thereby improving the crystal growth quality of other layers of materials on the first semiconductor layer 130.

[0104] In step S210, refer to Figure 5The active layer 131 can be used to provide optical gain, convert electrical energy into light energy, and thus generate laser. The active layer 131 can be composed of a sandwich structure consisting of a lower confinement layer and an upper confinement layer with higher band gap energy and lower refractive index on both sides, and a multi-quantum well pair located in the middle with lower band gap energy and the highest refractive index. The materials of the multi-quantum well layer and the upper confinement layer and the lower confinement layer located on opposite sides of the quantum well layer can all be undoped AlGaInAs or InGaAsP.

[0105] In step S220, refer to Figure 5 The second semiconductor layer 132 can be used as a waveguide layer, mainly to regulate the coupling strength of the light field and the grating together with the grating layer 120. The type of doping ions in the second semiconductor layer 132 is opposite to the type of doping ions in the first semiconductor layer 130. For example, the first semiconductor layer 130 is doped with N-type doping ions, and the second semiconductor layer 132 is doped with P-type doping ions.

[0106] Further, see Figure 5 , the refractive index of the active layer 131 can be set to the maximum, and the energy band width can be set to the minimum. At this time, the light field intensity in the area where the active layer 131 is located can reach the maximum. After the forward bias voltage is applied to both sides of the active layer 131, electrons flow from the first semiconductor layer 130 on the N side to the second semiconductor layer 132 on the P side, and holes flow from the second semiconductor layer 132 on the P side to the first semiconductor layer 130 on the N side. In the multi-quantum well region, electrons and holes meet and generate photons through recombination, while the upper and lower confinement layers with higher band gap energy can respectively block and restrict the migration of holes and electrons to the non-multi-quantum well region. Therefore, the presence of the confinement layer can simultaneously confine photons and electrons in the light-emitting area of ​​the active layer 131, thereby improving the recombination efficiency of electrons and holes and obtaining high quantum efficiency.

[0107] In step S400, refer to Figure 8 The ridge waveguide structure includes a third semiconductor layer 133 , a fourth semiconductor layer 134 and an electrode contact layer 135 .

[0108] The third semiconductor layer 133 is used to protect the grating layer 120 from external pollution, scratches, etc. The fourth semiconductor layer 134 can be used as a waveguide layer, and the thickness of the fourth semiconductor layer 134 can be greater than or equal to 1.5 μm, thereby effectively avoiding interference and absorption of the light field by the electrode contact layer 135 with a higher doping concentration and the P-type electrode layer 138 on the surface.

[0109] The electrode contact layer 135 can be used as a P-type ohmic contact layer, and the electrode contact layer 135 plays a role in current conduction, thereby conducting the two electrode layers. The electrode contact layer 135 can achieve ohmic contact by heavy doping, so that the semiconductor material and the metal material can achieve good conduction.

[0110] The ridge waveguide structure 139 is not only a channel for injecting electrons, but also provides light field confinement in the Y direction. By adjusting the width of the ridge waveguide structure 139 in the Y direction, the transverse mode and far-field divergence angle of the laser 100 can be adjusted to achieve single transverse mode lasing. At this time, the ridge waveguide structure 139 can be located at least in the first grating area 123 on the substrate 110. Of course, the ridge waveguide structure 139 can also be located in the first grating area 123 and the second grating area 124.

[0111] When forming the ridge waveguide structure 139, the third semiconductor material layer 1330, the fourth semiconductor material layer and the electrode contact material layer can be formed in sequence, and then the electrode contact layer 135, the fourth semiconductor layer 134, and the third semiconductor layer 133 are etched in sequence by combining dry and wet etching. After etching, the third semiconductor layer 133, the fourth semiconductor layer 134, and the electrode contact layer 135 form a ridge waveguide structure.

[0112] In step S410, a dielectric material layer may be formed on the entire surface, and then the dielectric material layer located on the top surface of the ridge waveguide structure 139 is removed to expose at least a portion of the electrode contact layer 135, and the remaining dielectric material layer forms a dielectric layer 136. The dielectric layer 136 may provide better insulation for the sidewalls and the grating layer 120 exposed by the ridge waveguide structure 139.

[0113] In step S420, refer to Figure 8 , the P-type electrode layer 138 can serve as a front metal electrode.

[0114] In step S430, refer to Figure 8 The N-type electrode layer 137 can be used as a metal electrode on the back side. The P-type electrode layer 138 and the N-type electrode layer 137 are used to inject current.

[0115] It should be understood that although Figure 4 , Figures 9 to 11 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 4 , Figures 9 to 11 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0116] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that "this embodiment" or "one embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification may not necessarily refer to the same embodiment.

[0117] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features of the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The embodiments described above only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all fall within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the attached claims. The above description is only a preferred implementation method of the present disclosure, and does not limit the scope of the patent of the present disclosure. All equivalent structural transformations made by using the contents of the present disclosure specification and drawings under the inventive concept of the present disclosure, or direct / indirect application in other related technical fields are included in the scope of protection of the patent of the present disclosure.

Claims

1. A laser, characterized in that: include: substrate; A grating layer is located on one side of the substrate, and includes a plurality of first refractive parts and second refractive parts which are alternately arranged and have different refractive indices. The grating layer has a first grating region and a second grating region. The second grating region is asymmetrically arranged on both sides of the first grating region. A period formed by the first refractive parts and the second refractive parts in the first grating region is a first period. A period formed by the first refractive parts and the second refractive parts in the second grating region is a second period. The first period is not equal to the second period.

2. The laser according to claim 1, characterized in that In a first direction, the length of the first refractive portion located in the first grating area is different from the length of the first refractive portion located in the second grating area, and / or the length of the second refractive portion located in the first grating area is different from the length of the second refractive portion located in the second grating area, and the first direction is the arrangement direction of the first refractive portion and the second refractive portion.

3. The laser according to claim 2, characterized in that The length of the first refractive portion in the first grating region is greater than the length of the first refractive portion in the second grating region, and / or the length of the second refractive portion in the first grating region is greater than the length of the second refractive portion in the second grating region.

4. The laser according to claim 3, characterized in that In the first direction, the first grating region has a first length, and the first period and the first length satisfy: P=Lp / Λ-Lp / Λ0=0.5±n, wherein P is the target phase of the grating layer, Lp is the first length, Λ is the first period, Λ0 is the second period, and n is 0 or a positive integer.

5. The laser according to claim 4, characterized in that n is greater than or equal to 1.

6. The laser according to claim 4, characterized in that The second grating region has a second length, the sum of the first length and the second length is the length of the grating layer, and the ratio of the first length to the length of the grating layer is in the range of 0.1-0.

3.

7. The laser according to claim 1, characterized in that The first refractive portion and the second refractive portion have the same doping type.

8. The laser according to claim 1, characterized in that The refractive index of the first refractive portion is lower than the refractive index of the second refractive portion. The material of the first refractive portion includes InP, and the material of the second refractive portion includes P-InGaAsP.

9. A method for preparing a laser, characterized in that: include: providing a substrate; A grating layer is formed on one side of the substrate, the grating layer includes a plurality of first refractive parts and second refractive parts which are alternately arranged and have different refractive indices, the grating layer has a first grating region and a second grating region, the second grating region is asymmetrically arranged on both sides of the first grating region, a period formed by the first refractive parts and the second refractive parts in the first grating region is a first period, a period formed by the first refractive parts and the second refractive parts in the second grating region is a second period, and the first period is not equal to the second period.

10. The method for preparing a laser according to claim 9, characterized in that: The step of forming a grating layer on one side of the substrate comprises: forming a grating material layer on one side of the substrate; Patterning the grating material layer to form a plurality of grooves, with the first refractive parts formed on both sides of the grooves; The groove is filled to form the second refractive portion.

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