A vertical cavity surface emitting laser and a method for manufacturing the same

Abstract

A vertical cavity surface emitting laser and a preparation method thereof, relating to the field of semiconductor technology, comprising a substrate, and an N-type Bragg reflector layer, a quantum well layer and a P-type Bragg reflector layer stacked in sequence on the substrate, the P-type Bragg reflector layer comprising a composite oxide layer and a sub-Bragg reflector layer with a current limiting hole stacked in sequence, the composite oxide layer comprising at least one mixed oxide layer, the mixed oxide layer comprising at least one group of first AlGaAs layers and second AlGaAs layers arranged alternately, the sub-Bragg reflector layer comprising at least one group of third AlGaAs layers and fourth AlGaAs layers arranged alternately, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer, the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer and the Al content in the second AlGaAs layer increase in sequence. The vertical cavity surface emitting laser and the preparation method thereof can solve the problem in the prior art that the length of the resonance cavity increases with the increase in the number of oxide layers.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a vertical cavity surface emitting laser and a preparation method thereof. Background Art

[0002] Vertical-Cavity Surface-Emitting Laser (VCSEL), also known as vertical resonant cavity surface-emitting laser, emits laser perpendicular to the top surface, which is different from edge-emitting laser, which is generally manufactured by cutting independent chips and emits laser from the edge.

[0003] The vertical cavity surface emitting laser in the prior art usually includes an N-type Bragg reflector, a quantum well, an oxide layer and a P-type Bragg reflector which are sequentially stacked on a substrate. When the oxide layer is multi-layered, the distance between the N-type Bragg reflector and the P-type Bragg reflector (i.e., the length of the resonance cavity) will increase accordingly, affecting the mode distance between the laser longitudinal modes, as well as the optical confinement factor and the threshold condition. At the same time, it is also easy to form a multi-modal laser output spectrum. Summary of the invention

[0004] The object of the present invention is to provide a vertical cavity surface emitting laser and a preparation method thereof, which can solve the problem in the prior art that the length of the resonance cavity increases with the increase in the number of oxide layers.

[0005] The embodiment of the present invention is achieved as follows:

[0006] According to one aspect of an embodiment of the present invention, a vertical cavity surface emitting laser is provided, comprising a substrate, and an N-type Bragg reflector layer, a quantum well layer and a P-type Bragg reflector layer stacked in sequence on the substrate, the P-type Bragg reflector layer comprising a composite oxide layer and a sub-Bragg reflector layer having a current limiting hole stacked in sequence, the composite oxide layer comprising at least one mixed oxide layer, the mixed oxide layer comprising at least one group of first AlGaAs layers and second AlGaAs layers alternately arranged, the sub-Bragg reflector layer comprising at least one group of third AlGaAs layers and fourth AlGaAs layers alternately arranged, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer, and the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer and the Al content in the second AlGaAs layer increase in sequence.

[0007] As an practicable manner, the hybrid oxide layer includes a plurality of groups of first AlGaAs layers and second AlGaAs layers alternately arranged, each group of the second AlGaAs layers is provided with sub-current limiting holes, the sub-current limiting holes of the plurality of groups of the second AlGaAs layers correspond to each other along the stacking direction to form the current limiting holes, and the apertures of the sub-current limiting holes of the plurality of groups of the second AlGaAs layers are equal.

[0008] As an practicable manner, the composite oxide layer includes a plurality of mixed oxide layers, each of the mixed oxide layers is provided with a sub-current limiting hole, the sub-current limiting holes of the plurality of mixed oxide layers correspond to each other along the stacking direction to form the current limiting hole, and the apertures of the sub-current limiting holes of the plurality of mixed oxide layers gradually decrease along the direction from the P-type Bragg reflector layer to the quantum well layer.

[0009] As an implementable manner, the number of the fourth AlGaAs layers is greater than the number of the second AlGaAs layers.

[0010] As an implementable manner, a first buffer layer is disposed between the N-type Bragg reflector layer and the quantum well layer, and a second buffer layer is disposed between the quantum well layer and the P-type Bragg reflector layer.

[0011] As an practicable manner, a contact layer is provided on a side of the sub-Bragg reflector layer facing away from the composite oxide layer, and the N-type Bragg reflector layer and the quantum well layer form a step structure.

[0012] As an implementable manner, a first electrode is disposed on a side of the contact layer facing away from the sub-Bragg reflector layer, and a second electrode is disposed on a table surface of the N-type Bragg reflector layer close to the quantum well layer.

[0013] As an implementable manner, the first electrode is a ring-shaped electrode, and the current limiting hole and the light window formed by the ring-shaped electrode correspond to each other in a stacking direction.

[0014] As an implementable manner, the first electrode is a P-type electrode, and the second electrode is an N-type electrode.

[0015] According to another aspect of an embodiment of the present invention, a method for preparing a vertical cavity surface emitting laser is provided, comprising: sequentially forming an N-type Bragg reflector layer and a quantum well layer on a substrate; forming a composite oxide layer on the quantum well layer, wherein the composite oxide layer comprises at least one mixed oxide layer, and the mixed oxide layer comprises at least one group of alternately arranged first AlGaAs layers and second AlGaAs layers; forming a sub-Bragg reflector layer on the composite oxide layer, wherein the sub-Bragg reflector layer comprises at least one group of alternately arranged third AlGaAs layers and fourth AlGaAs layers, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer, and the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer, and the Al content in the second AlGaAs layer increase sequentially; and laterally oxidizing the composite oxide layer to form a current limiting hole in the composite oxide layer.

[0016] The beneficial effects of the embodiments of the present invention include:

[0017] The vertical cavity surface emitting laser comprises a substrate, and an N-type Bragg reflector layer, a quantum well layer and a P-type Bragg reflector layer which are sequentially stacked on the substrate. The P-type Bragg reflector layer comprises a composite oxide layer and a sub-Bragg reflector layer which are sequentially stacked and have a current limiting hole. The composite oxide layer comprises at least one mixed oxide layer, which comprises at least one group of first AlGaAs layers and second AlGaAs layers which are alternately arranged. The sub-Bragg reflector layer comprises at least one group of third AlGaAs layers and fourth AlGaAs layers which are alternately arranged. The content of Al in the first AlGaAs layer is equal to the content of Al in the third AlGaAs layer, and the content of Al in the first AlGaAs layer, the content of Al in the fourth AlGaAs layer and the content of Al in the second AlGaAs layer increase sequentially. At least one group of the fourth AlGaAs layer on the side away from the quantum well layer in the original P-type Bragg reflector layer remains unchanged, so that at least one group of the fourth AlGaAs layer cooperates with the corresponding third AlGaAs layer to form a sub-Bragg reflector layer. At the same time, at least one group of the fourth AlGaAs layer on the side close to the quantum well layer in the original P-type Bragg reflector layer is replaced with a second AlGaAs layer, so that at least one group of the second AlGaAs layer cooperates with the corresponding first AlGaAs layer to form a mixed oxide layer, that is, the Al content in at least one group of the high Al layer on the side close to the quantum well layer in the original P-type Bragg reflector layer is increased. Compared with the original fourth AlGaAs layer, the replaced second AlGaAs layer is more easily oxidized in lateral oxidation to form a current limiting hole, so as to pass the current limiting hole. The hole making guides and limits the flow of current, so that the current can be confined in the current limiting hole when flowing through the composite oxide layer, and a higher intracavity current density can be injected into the quantum well layer, thereby obtaining a higher internal quantum efficiency, and then realizing single-mode output, that is, the composite oxide layer has the function of realizing single-mode output of the traditional oxide layer, and no matter how many mixed oxide layers the composite oxide layer includes, each mixed oxide layer includes several groups of first AlGaAs layers and second AlGaAs layers, it will not affect the length of the resonance cavity. In addition, the length of the resonance cavity can be further reduced by removing the traditional oxide layer originally arranged between the quantum well and the P-type Bragg reflector, thereby avoiding affecting the mode distance between the laser longitudinal modes, as well as the optical confinement factor and the threshold condition, and ensuring single-mode output. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 One of the structural schematic diagrams of the vertical cavity surface emitting laser provided in an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the structure of a composite oxide layer provided in the first embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the structure of a composite oxide layer provided in a second embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the structure of a composite oxide layer provided in a third embodiment of the present invention;

[0023] Figure 5 A schematic diagram of the structure of a composite oxide layer provided in a fourth embodiment of the present invention;

[0024] Figure 6 A schematic structural diagram of a sub-Bragg reflector layer provided in an embodiment of the present invention;

[0025] Figure 7 A second structural schematic diagram of a vertical cavity surface emitting laser provided in an embodiment of the present invention;

[0026] Figure 8 A schematic flow chart of a method for preparing a vertical cavity surface emitting laser provided in an embodiment of the present invention.

[0027] Icon: 100-vertical cavity surface emitting laser; 10-substrate; 20-N-type Bragg reflector layer; 30-first buffer layer; 40-quantum well layer; 50-second buffer layer; 60-P-type Bragg reflector layer; 61-composite oxide layer; 611, 612-mixed oxide layer; 611a, 612a-first AlGaAs layer; 611b, 612b-second AlGaAs layer; 613-current limiting hole; 613a, 613b-sub-current limiting hole; 62-sub-Bragg reflector layer; 621-third AlGaAs layer; 622-fourth AlGaAs layer; 70-contact layer; 80-first electrode; 81-optical window; 90-second electrode. DETAILED DESCRIPTION

[0028] The embodiments set forth below represent information necessary to enable those skilled in the art to practice the embodiments, and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the applications of these concepts not specifically proposed herein. It should be understood that these concepts and applications are within the scope of the present disclosure and the appended claims.

[0029] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] It should be understood that when an element (such as a layer, region or substrate) is referred to as "on another element" or "extending onto another element", it can be directly on another element or directly extended onto another element, or there can also be an intervening element. On the contrary, when an element is referred to as "directly on another element" or "directly extending onto another element", there is no intervening element. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as "on another element" or "extending onto another element", it can be directly on another element or directly extended onto another element, or there can also be an intervening element. On the contrary, when an element is referred to as "directly on another element" or "extending directly onto another element", there is no intervening element. It should also be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to another element, or there can be an intervening element. On the contrary, when an element is referred to as "directly connected" or "directly coupled" to another element, there is no intervening element.

[0031] Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe the relationship of one element, layer or region to another element, layer or region as shown in the figures.

[0032] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the features, integers, steps, operations, elements, and / or parts, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups of the above.

[0033] Unless otherwise defined, all terms (including 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. It should also be understood that the terms used herein should be interpreted as having the same meaning as they do in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless clearly defined in this article.

[0034] Please refer to Figures 1 to 7 The present application provides a vertical cavity surface emitting laser 100, comprising a substrate 10, and an N-type Bragg reflector layer 20, a quantum well layer 40 and a P-type Bragg reflector layer 60 stacked in sequence on the substrate 10, the P-type Bragg reflector layer 60 comprising a composite oxide layer 61 and a sub-Bragg reflector layer 62 stacked in sequence with a current limiting hole 613, the composite oxide layer 61 comprising at least one hybrid oxide layer, the hybrid oxide layer comprising at least one group of first AlGaAs layers and second AlGaAs layers alternately arranged, the sub-Bragg reflector layer 62 comprising at least one group of third AlGaAs layers 621 and fourth AlGaAs layers 622 alternately arranged, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer 621, the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer 622 and the Al content in the second AlGaAs layer increase in sequence.

[0035] It should be noted that if Figure 1 and Figure 7 As shown, the vertical cavity surface emitting laser 100 includes a substrate 10, on which an N-type Bragg reflector layer 20, a quantum well layer 40 and a P-type Bragg reflector layer 60 are sequentially stacked, wherein the P-type Bragg reflector layer 60 includes a composite oxide layer 61 having a current limiting hole 613 and a sub-Bragg reflector layer 62 which are sequentially stacked. Figures 2 to 5 As shown, the composite oxide layer 61 includes at least one mixed oxide layer, and the mixed oxide layer includes at least one set of first AlGaAs layers and second AlGaAs layers alternately arranged, such as Figure 6As shown, the sub-Bragg reflector layer 62 includes at least one group of alternately arranged third AlGaAs layers 621 and fourth AlGaAs layers 622, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer 621, the first AlGaAs layer and the third AlGaAs layer 621 are only distinguished by names for the convenience of description and do not have substantial differences, the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer 622 and the Al content in the second AlGaAs layer increase successively, so that the second AlGaAs layer is more easily oxidized than the first AlGaAs layer and the fourth AlGaAs layer 622.

[0036] The original P-type Bragg reflector layer 60 includes at least two groups of third AlGaAs layers 621 and fourth AlGaAs layers 622 that are alternately arranged. In the present application, at least one group of fourth AlGaAs layers 622 on the side away from the quantum well layer 40 in the original P-type Bragg reflector layer 60 is kept unchanged, so that at least one group of fourth AlGaAs layers 622 cooperate with the corresponding third AlGaAs layers 621 to form a sub-Bragg reflector layer 62. At the same time, at least one group of fourth AlGaAs layers 622 on the side close to the quantum well layer 40 in the original P-type Bragg reflector layer 60 is replaced with a second AlGaAs layer, so that at least one group of second AlGaAs layers cooperate with the corresponding first AlGaAs layer to form a mixed oxide layer, that is, the Al content in at least one group of high Al layers on the side close to the quantum well layer 40 in the original P-type Bragg reflector layer 60 is increased, and the replaced second AlGaAs layer is compared with the original fourth AlGaAs layer. The GaAs layer 622 is more easily oxidized in the lateral oxidation to form a current limiting hole 613, so as to guide and limit the flow of current through the current limiting hole 613, so that the current can be confined in the current limiting hole 613 when flowing through the composite oxide layer 61, so that a higher intracavity current density can be injected into the quantum well layer 40, thereby obtaining a higher internal quantum efficiency, and then realizing single-mode output, that is, the composite oxide layer 61 has the function of realizing single-mode output of the traditional oxide layer, and no matter how many mixed oxide layers the composite oxide layer 61 includes, each mixed oxide layer includes several groups of first AlGaAs layers and second AlGaAs layers, it will not affect the length of the resonance cavity. In addition, the length of the resonance cavity can be further reduced by removing the traditional oxide layer originally arranged between the quantum well and the P-type Bragg reflector, thereby avoiding affecting the mode distance between the laser longitudinal modes, as well as the optical confinement factor and the threshold condition, and ensuring single-mode output.

[0037] Regarding the actual values ​​of the Al content in the first AlGaAs layer, the second AlGaAs layer, the third AlGaAs layer 621 and the fourth AlGaAs layer 622, those skilled in the art should be able to make reasonable selections and designs according to actual conditions, and no specific restrictions are made here. For example, the Al content in the first AlGaAs layer and the Al content in the third AlGaAs layer 621 are both 10%, the Al content in the second AlGaAs layer is 98%, and the Al content in the fourth AlGaAs layer 622 is 90%, so that the refractive index Δn of each group of the first AlGaAs layer and the second AlGaAs layer arranged alternately is 0.5592, and the refractive index Δn of each group of the third AlGaAs layer 621 and the fourth AlGaAs layer 622 arranged alternately is 0.5114, so that the refractive index of the hybrid oxide layer (i.e., the composite oxide layer 61) meets the actual requirements of the refractive index of the sub-Bragg reflector layer 62 (i.e., the original P-type Bragg reflector layer 60).

[0038] like Figure 2 As shown, the hybrid oxide layer 611 includes a set of first AlGaAs layers 611a and second AlGaAs layers 611b arranged alternately. In order to further enhance the guiding and limiting effect of the current limiting hole 613 of the composite oxide layer 61 on the current flow direction, as shown in FIG. Figure 3 , Figure 5 and Figure 7 As shown, as an implementable manner, the hybrid oxide layer 611 includes a plurality of groups (for example, m1 groups) of first AlGaAs layers 611a and second AlGaAs layers 611b that are alternately arranged, each group of second AlGaAs layers 611b is provided with a sub-current limiting hole 613a, and the sub-current limiting holes 613a of the plurality of groups of second AlGaAs layers 611b correspond to each other along the stacking direction to form the current limiting hole 613. Since the Al content in each group of second AlGaAs layers 611b is the same, the oxidation rate of each group of second AlGaAs layers 611b is the same, so that the apertures of the sub-current limiting holes 613a of the plurality of groups of second AlGaAs layers 611b are equal.

[0039] like Figure 2 As shown, the composite oxide layer 61 includes a mixed oxide layer 611. In order to further enhance the guiding and limiting effect of the current limiting hole 613 of the composite oxide layer 61 on the current flow direction, as shown in FIG. Figure 4 , Figure 5 and Figure 7As shown, as an implementable method, the composite oxide layer 61 includes multiple mixed oxide layers, each mixed oxide layer is provided with a sub-current limiting hole, the sub-current limiting holes of the multiple mixed oxide layers correspond to each other along the stacking direction to form a current limiting hole 613, and the apertures of the sub-current limiting holes of the multiple mixed oxide layers gradually decrease along the direction from the P-type Bragg reflector layer 60 to the quantum well layer 40.

[0040] For example, Figure 4 , Figure 5 and Figure 7 As shown, the composite oxide layer 61 includes two mixed oxide layers, namely, a mixed oxide layer 611 and a mixed oxide layer 612. The mixed oxide layer 611 is provided with a sub-current limiting hole 613a, and the mixed oxide layer 612 is provided with a sub-current limiting hole 613b. The sub-current limiting holes of the two mixed oxide layers correspond to each other along the stacking direction to form a current limiting hole 613. The sub-current limiting holes of each mixed oxide layer can guide and limit the flow direction of the current. The apertures of the sub-current limiting holes of the two mixed oxide layers gradually decrease along the direction from the P-type Bragg reflector layer 60 to the quantum well layer 40, that is, the aperture of the sub-current limiting hole 613b of the mixed oxide layer 612 is larger than the aperture of the sub-current limiting hole 613a of the mixed oxide layer 611, so as to gradually guide the flow direction of the current, thereby further shortening the current path when the current flows through the composite oxide layer 61, thereby making the reaction speed and working efficiency of the device better.

[0041] The aperture of the sub-current limiting hole 613b of the hybrid oxide layer 612 is larger than the aperture of the sub-current limiting hole 613a of the hybrid oxide layer 611, which can be obtained by utilizing the fact that the AlGaAs material with a lower Al content is oxidized at a slower rate under the same oxidation conditions, that is, it is only necessary to make the Al content in the second AlGaAs layer 612b of the hybrid oxide layer 612 smaller than the Al content in the second AlGaAs layer 611b of the hybrid oxide layer 611. For example, the Al content in the first AlGaAs layer 611a of the hybrid oxide layer 611 and the Al content in the first AlGaAs layer 612a of the hybrid oxide layer 612 are both 10%, the Al content in the second AlGaAs layer 611b of the hybrid oxide layer 611 is 98%, and the Al content in the second AlGaAs layer 612b of the hybrid oxide layer 612 is 96%.

[0042] It is worth noting that the Al content in the second AlGaAs layer of the hybrid oxide layer close to the sub-Bragg reflector layer 62 in the composite oxide layer 61 should not be too close to the Al content in the fourth AlGaAs layer 622 of the sub-Bragg reflector layer 62, so as to avoid erroneous oxidation of the fourth AlGaAs layer 622 of the sub-Bragg reflector layer 62 when the control accuracy is low during lateral oxidation.

[0043] As an practicable manner, under the premise that the number of groups of the third AlGaAs layer 621 and the fourth AlGaAs layer 622 included in the original P-type Bragg reflector layer 60 remains unchanged, the number of the fourth AlGaAs layer 622 (for example, n groups) is greater than the number of the second AlGaAs layer, so as to ensure that the P-type Bragg reflector layer 60 composed of the composite oxide layer 61 and the sub-Bragg reflector layer 62 meets the design requirements of the original P-type Bragg reflector layer 60. Figure 3 and Figure 6 As shown, when the composite oxide layer 61 includes a mixed oxide layer 611, n is greater than m1, as shown in FIG. Figure 5 and Figure 6 As shown, when the composite oxide layer 61 includes two mixed oxide layers (ie, the mixed oxide layer 611 and the mixed oxide layer 612), n is greater than the sum of m1 and m2.

[0044] like Figure 1 and Figure 7 As shown, as an implementable manner, a first buffer layer 30 is arranged between the N-type Bragg reflector layer 20 and the quantum well layer 40, and a second buffer layer 50 is arranged between the quantum well layer 40 and the P-type Bragg reflector layer 60, so as to improve the device performance through the first buffer layer 30 and the second buffer layer 50.

[0045] like Figure 7 As shown, as an implementable manner, a contact layer 70 is provided on the side of the sub-Bragg reflector layer 62 facing away from the composite oxide layer 61, so that when the device is turned on, current is injected through the contact layer 70, and the N-type Bragg reflector layer 20 and the quantum well layer 40 form a step structure, so as to realize lateral oxidation of the device through the step structure.

[0046] like Figure 7 As shown, as an implementable manner, a first electrode 80 is disposed on one side of the contact layer 70 facing away from the ion Bragg reflector layer 62, and a second electrode 90 is disposed on the table surface of the N-type Bragg reflector layer 20 close to the quantum well layer 40, so as to realize electrical connection of the device through the first electrode 80 and the second electrode 90. Figure 7 As shown, as an implementable manner, the first electrode 80 is a P-type electrode, and the second electrode 90 is an N-type electrode.

[0047] like Figure 7 As shown, as an implementable manner, the first electrode 80 is a ring electrode, the current limiting hole 613 corresponds to the light window 81 formed by the ring electrode in the stacking direction, and the aperture of the current limiting hole 613 should be greater than or equal to the aperture of the light window 81 formed by the ring electrode to avoid the oxidized area from affecting the light output of the quantum well layer 40. For example, Figure 7 As shown, when the composite oxide layer 61 includes two mixed oxide layers, the aperture D1 of the sub-current limiting hole 613b of the mixed oxide layer 612 facing away from the quantum well side is larger than the aperture of the light window 81, and the aperture D2 of the sub-current limiting hole 613a of the mixed oxide layer 611 close to the quantum well side is equal to the aperture of the light window 81.

[0048] Please refer to Figure 8 The present application also provides a method for preparing a vertical cavity surface emitting laser 100, comprising:

[0049] S110, sequentially forming an N-type Bragg reflector layer 20 and a quantum well layer 40 on a substrate 10;

[0050] S210, forming a composite oxide layer 61 on the quantum well layer 40, wherein the composite oxide layer 61 includes at least one mixed oxide layer, and the mixed oxide layer includes at least one group of first AlGaAs layers and second AlGaAs layers that are alternately arranged;

[0051] S310, forming a sub-Bragg reflector layer 62 on the composite oxide layer 61, wherein the sub-Bragg reflector layer 62 includes at least one group of third AlGaAs layers 621 and fourth AlGaAs layers 622 that are alternately arranged, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer 621, and the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer 622, and the Al content in the second AlGaAs layer increase in sequence;

[0052] S410 , performing lateral oxidation on the composite oxide layer 61 to form a current limiting hole 613 in the composite oxide layer 61 .

[0053] It should be noted that at least one of the fourth AlGaAs layers 622 of the original P-type Bragg reflector layer 60 near the quantum well layer 40 is replaced with a second AlGaAs layer, so that at least one of the second AlGaAs layers cooperates with the corresponding first AlGaAs layer to form a hybrid oxide layer, that is, the Al content in at least one of the high Al layers of the original P-type Bragg reflector layer 60 near the quantum well layer 40 is increased. Compared with the original fourth AlGaAs layer 622, the replaced second AlGaAs layer is more easily oxidized in the lateral oxidation to form a current limiting hole 613, so as to guide and limit the flow direction of the current through the current limiting hole 613, so that the current can flow through the composite oxide layer 6 1 is confined in the current limiting hole 613, so that a higher intracavity current density can be injected into the quantum well layer 40, thereby obtaining a higher internal quantum efficiency, and further realizing single-mode output, that is, the composite oxide layer 61 has the function of realizing single-mode output of the traditional oxide layer, and no matter how many mixed oxide layers the composite oxide layer 61 includes, each mixed oxide layer includes several groups of first AlGaAs layers and second AlGaAs layers, it will not affect the length of the resonance cavity. In addition, by removing the traditional oxide layer originally arranged between the quantum well and the P-type Bragg reflector, the length of the resonance cavity can be further reduced, thereby avoiding affecting the mode distance between the laser longitudinal modes, as well as the optical confinement factor and the threshold condition, and ensuring single-mode output.

[0054] The above description is only an optional embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0055] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A vertical cavity surface emitting laser, characterized in that: The invention comprises a substrate, and an N-type Bragg reflector layer, a quantum well layer and a P-type Bragg reflector layer which are sequentially stacked on the substrate, wherein the P-type Bragg reflector layer comprises a composite oxide layer and a sub-Bragg reflector layer which are sequentially stacked and have a current limiting hole, the composite oxide layer comprises at least one mixed oxide layer, the mixed oxide layer comprises at least one group of first AlGaAs layers and second AlGaAs layers which are alternately arranged, the sub-Bragg reflector layer comprises at least one group of third AlGaAs layers and fourth AlGaAs layers which are alternately arranged, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer, and the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer and the Al content in the second AlGaAs layer increase sequentially.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: The hybrid oxide layer includes multiple groups of alternately arranged first AlGaAs layers and second AlGaAs layers, each group of the second AlGaAs layers is provided with sub-current limiting holes, the sub-current limiting holes of the multiple groups of the second AlGaAs layers correspond to each other along the stacking direction to form the current limiting holes, and the apertures of the sub-current limiting holes of the multiple groups of the second AlGaAs layers are equal.

3. The vertical cavity surface emitting laser according to claim 1, characterized in that: The composite oxide layer includes a plurality of mixed oxide layers, each of which is provided with a sub-current limiting hole, and the sub-current limiting holes of the plurality of mixed oxide layers correspond to each other along the stacking direction to form the current limiting hole, and the apertures of the sub-current limiting holes of the plurality of mixed oxide layers gradually decrease along the direction from the P-type Bragg reflector layer to the quantum well layer.

4. The vertical cavity surface emitting laser according to claim 1, characterized in that: The number of the fourth AlGaAs layers is greater than the number of the second AlGaAs layers.

5. The vertical cavity surface emitting laser according to claim 1, characterized in that: A first buffer layer is disposed between the N-type Bragg reflector layer and the quantum well layer, and a second buffer layer is disposed between the quantum well layer and the P-type Bragg reflector layer.

6. The vertical cavity surface emitting laser according to claim 1, characterized in that: A contact layer is provided on a side of the sub-Bragg reflector layer away from the composite oxide layer, and the N-type Bragg reflector layer and the quantum well layer form a step structure.

7. The vertical cavity surface emitting laser according to claim 6, characterized in that: A first electrode is disposed on a side of the contact layer facing away from the sub-Bragg reflector layer, and a second electrode is disposed on a table surface of the N-type Bragg reflector layer close to the quantum well layer.

8. The vertical cavity surface emitting laser according to claim 7, characterized in that: The first electrode is a ring-shaped electrode, and the current limiting hole corresponds to a light window formed by the ring-shaped electrode in a stacking direction.

9. The vertical cavity surface emitting laser according to claim 7, characterized in that: The first electrode is a P-type electrode, and the second electrode is an N-type electrode.

10. A method for preparing a vertical cavity surface emitting laser, characterized in that: include: An N-type Bragg reflector layer and a quantum well layer are sequentially formed on a substrate; forming a composite oxide layer on the quantum well layer, wherein the composite oxide layer comprises at least one mixed oxide layer, and the mixed oxide layer comprises at least one group of first AlGaAs layers and second AlGaAs layers alternately arranged; forming a sub-Bragg reflector layer on the composite oxide layer, wherein the sub-Bragg reflector layer comprises at least one group of third AlGaAs layers and fourth AlGaAs layers which are alternately arranged, the Al content in the first AlGaAs layer is equal to the Al content in the third AlGaAs layer, and the Al content in the first AlGaAs layer, the Al content in the fourth AlGaAs layer, and the Al content in the second AlGaAs layer increase in sequence; The composite oxide layer is laterally oxidized to form a current limiting hole in the composite oxide layer.

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