CN217934573U

CN217934573U - Vertical cavity surface emitting laser

Info

Publication number: CN217934573U
Application number: CN202221815587.8U
Authority: CN
Inventors: 潘德烈
Original assignee: Shenzhen Demingli Electronics Co Ltd
Current assignee: Shenzhen Jiaminli Photoelectric Co ltd
Priority date: 2022-07-13
Filing date: 2022-07-13
Publication date: 2022-11-29
Anticipated expiration: 2032-07-13

Abstract

The application provides a vertical cavity surface emitting laser, relates to laser technical field, includes the substrate and stacks gradually bottom Bragg reflector, active layer, the oxidation restrictive coating that has first current window and the top Bragg reflector that has the second current window on the substrate, and the orthographic projection coincidence of first current window and second current window on the substrate. Thereby through the combined action of the current window in the oxidation restriction layer and the current window in the Bragg reflector in top, can improve the restriction effect of electric current on the one hand to make higher intracavity current density pour into the active layer, so that obtain higher inside quantum efficiency, increase intracavity reflection loss when on the other hand can reduce the resonant cavity area, from this, be convenient for more form the single mode, thereby make the light beam of outgoing can form ideal gaussian beam.

Description

Vertical cavity surface emitting laser

Technical Field

The application relates to the technical field of lasers, in particular to a vertical cavity surface emitting laser.

Background

A Vertical-Cavity Surface-Emitting Laser (VCSEL) is a Laser with a light-Emitting direction perpendicular to the Surface of a resonant Cavity, has the advantages of small threshold current, small divergence angle, circularly symmetric light spot, easy two-dimensional integration and the like, and is widely applied to the fields of optical interconnection, optical storage, optical communication and the like.

The current is usually limited by the oxidation limiting layer in the existing VCSEL device, so that the current can be injected into the active layer through the current window of the oxidation limiting layer in a concentrated mode, the light emitting quality is improved, but the light emitting form of the existing VCSEL device is basically multi-mode, and the problem of low quality still exists.

SUMMERY OF THE UTILITY MODEL

An object of the present application is to provide a vertical cavity surface emitting laser, which is not enough in the above prior art, so as to solve the problem of low light emitting quality of the existing VCSEL device.

In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

in one aspect of the embodiments of the present application, a vertical cavity surface emitting laser is provided, including a substrate, and a bottom bragg mirror, an active layer, an oxide confinement layer having a first current window, and a top bragg mirror having a second current window, which are sequentially stacked on the substrate, and orthographic projections of the first current window and the second current window on the substrate are overlapped.

Optionally, each of the bottom bragg mirror and/or the top bragg mirror includes a plurality of first refractive index layers and a plurality of second refractive index layers alternately arranged, and a difference between refractive indexes of the first refractive index layers and the second refractive index layers is greater than 0.5114.

Optionally, the difference in refractive index between the first refractive index layer and the second refractive index layer is 0.5592.

Optionally, the bottom bragg mirror and the active layer form a stepped structure.

Optionally, a first electrode is further disposed on a side of the top bragg reflector facing away from the oxide confinement layer, and a second electrode is disposed on a mesa of the bottom bragg reflector close to the active layer.

Optionally, the first electrode is a P-type electrode and the second electrode is an N-type electrode.

Optionally, a contact layer is disposed between the first electrode and the top bragg mirror.

Optionally, the first electrode is a ring electrode.

Optionally, a first buffer layer is further disposed between the bottom bragg reflector and the active layer, and a second buffer layer is further disposed between the active layer and the oxidation limiting layer.

Optionally, the active layer is a multiple quantum well layer.

The beneficial effect of this application includes:

the application provides a vertical cavity surface emitting laser, which comprises a substrate, a bottom Bragg reflector, an active layer, an oxidation limiting layer with a first current window and a top Bragg reflector with a second current window, wherein the bottom Bragg reflector, the active layer, the oxidation limiting layer with the first current window and the top Bragg reflector with the second current window are sequentially stacked on the substrate, and orthographic projections of the first current window and the second current window on the substrate are overlapped. Thereby through the combined action of the current window in the oxidation restriction layer and the current window in the Bragg reflector in top, can improve the restriction effect of electric current on the one hand to make higher intracavity current density pour into the active layer, so that obtain higher inside quantum efficiency, increase intracavity reflection loss when on the other hand can reduce the resonant cavity area, from this, be convenient for more form the single mode, thereby make the light beam of outgoing can form ideal gaussian beam.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 is a schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present disclosure;

fig. 2 is a second schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present disclosure;

fig. 3 is a third schematic structural diagram of a vertical cavity surface emitting laser according to an embodiment of the present disclosure.

Icon: 110-a substrate; 120-bottom bragg mirror; 130-a first buffer layer; 140-an active layer; 150-a second buffer layer; 160-an oxidized confinement layer; 170-a third buffer layer; 180-top bragg mirror; 190-a contact layer; 210-a first electrode; 220 — second electrode.

Detailed Description

The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

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

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or "extending" onto "another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there are no intervening elements present. Also, it will be understood that when an element such as a layer, region or substrate is referred to as being "on" or "extending over" another element, it can be directly on or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly extending" onto another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

Related terms such as "below" or "at" \8230303080 ", 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 illustrated in the figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

An aspect of the embodiments of the present application provides a vertical cavity surface emitting laser, through set up the current window in the top bragg reflector, and make the area of the current window in the top bragg reflector and the oxidation restriction layer equal, thereby through the combined action of the current window in the oxidation restriction layer and the current window in the top bragg reflector, on the one hand can improve the restriction effect of electric current, thereby make higher intracavity current density inject the active layer, so that obtain higher inside quantum efficiency, on the other hand can reduce increase intracavity reflection loss when resonant cavity area, therefore, be convenient for form the mode more, thereby make the emergent light beam can form ideal gaussian beam. Embodiments of the present application will be described below with reference to the accompanying drawings.

Referring to fig. 1, a vertical cavity surface emitting laser is shown, which includes a substrate 110, and a bottom bragg mirror 120, an active layer 140, an oxide confinement layer 160, and a top bragg mirror 180 sequentially stacked on the substrate 110.

The oxide confinement layer 160 has a first current window, so that the oxide confinement layer 160 can confine a current distribution region, as shown in fig. 2, the current flowing through the oxide confinement layer 160 is confined in the first current window through the first current window, and thus, the current density in the cavity injected into the active layer 140 can be increased preliminarily.

The top bragg reflector 180 has a second current window, and thus the top bragg reflector 180 can also limit the distribution area of the current, as shown in fig. 2, the current can be limited in the second current window when flowing through the top bragg reflector 180 through the second current window, so that the intra-cavity current density injected into the active layer 140 can be further improved, thereby obtaining higher internal quantum efficiency and improving the performance of the vertical cavity surface emitting laser.

With reference to fig. 1, orthographic projections of the first current window and the second current window on the substrate 110 are overlapped, in other words, a window area of the first current window is equal to a window area of the second current window, and the first current window and the second current window are opposite to each other along a thickness direction of the substrate 110, so that, through a combined action of the first current window and the second current window, as shown in fig. 2, on one hand, a current confinement effect can be improved, so that a higher intra-cavity current density is injected into the active layer 140, so as to obtain a higher internal quantum efficiency, as shown in fig. 3, on the other hand, intra-cavity reflection loss can be increased while a resonant cavity area is reduced, so that a single-mode can be formed more conveniently, and an emitted light beam can form an ideal gaussian light beam.

The first current window and the second current window in the present application have the same shape, but the present application is not limited to a specific shape, for example, the first current window and the second current window may be circular holes, square holes, or other forms. As shown in fig. 1, when the first current window and the second current window are circular holes, the apertures D of the first current window and the second current window are equal.

As shown in fig. 1, the top bragg reflector 180 includes a plurality of first refractive index layers and a plurality of second refractive index layers alternately arranged, that is, the plurality of first refractive index layers and the plurality of second refractive index layers are stacked in an ABAB manner, and the refractive indexes of the first refractive index layers and the second refractive index layers are different. Similarly, the bottom bragg reflector 120 may also include a plurality of first refractive index layers and a plurality of second refractive index layers that are alternately disposed, that is, the plurality of first refractive index layers and the plurality of second refractive index layers are stacked in an ABAB manner, and the refractive indexes of the first refractive index layers and the second refractive index layers are different.

The way of making the orthographic projections of the first current window and the second current window coincide on the substrate 110 may be implemented by controlling the oxidation rate, and it should be understood that, in the preparation of the vertical cavity surface emitting laser, the first current window on the oxidation limiting layer 160 is implemented by lateral oxidation, and similarly, the second current window in the top bragg mirror 180 may also destroy the reflection capability of the oxidized region by lateral oxidation to form the second current window in the top bragg mirror 180. Thus, the oxidation rates of the oxidized confinement layer 160 and the top bragg mirror 180 may be controlled such that the orthographic projections of the first current window and the second current window on the substrate 110 coincide.

For example: the oxidation rate of the top bragg mirror 180 may be controlled by varying the aluminum composition content of the top bragg mirror 180 (in view of the prior art)The current window is not usually disposed in the top bragg reflector 180, and therefore, the oxidation rate of the top bragg reflector 180 can be increased by increasing the content of the aluminum component of the top bragg reflector 180, so that the oxidation rates of the oxidation limiting layer 160 and the top bragg reflector 180 are kept consistent), and thus, by adjusting, so that the oxidation rate of the top bragg reflector 180 and the oxidation rate of the oxidation limiting layer 160 are kept consistent, the orthographic projections of the first current window and the second current window on the substrate 110 can be coincided. Specifically, the method comprises the following steps: the first and second refractive index layers in the top bragg mirror 180 are each AlGaAs layers having different aluminum component contents, for example: al (Al) _(0.98) Ga _(0.02) As/Al _(0.1) Ga _(0.9) As。

Further, by changing the aluminum component content of the first refractive index layer and the second refractive index layer, the refractive index difference of the first refractive index layer and the second refractive index layer can also be changed, and the refractive index difference can be increased by increasing the aluminum component, for example. Therefore, while the oxidation rate of the top bragg reflector 180 is consistent with the oxidation rate of the oxidized confinement layer 160 in the manner described above, the refractive index difference between the first refractive index layer and the second refractive index layer may be increased, so that the number of pairs included in the top bragg reflector 180 may be reduced while the reflectivity of the entire top bragg reflector 180 is not reduced (greater than 99%), and as shown in fig. 1, the thickness H of the corresponding top bragg reflector 180 may also be reduced as the number of pairs is reduced. The thickness H of the top bragg reflector 180 is reduced, and the equivalent series resistance of the top bragg reflector 180 can be correspondingly reduced, thereby reducing the voltage and the heat generation amount.

For example, in one embodiment, the difference between the refractive indices of the first refractive index layer and the second refractive index layer is greater than 0.5114 (the conventional refractive index difference is typically 0.5114), so that the logarithm included in the top bragg mirror 180 can be reduced while the reflectivity of the entire top bragg mirror 180 is not reduced (greater than 99%), and as shown in fig. 1, the thickness H of the corresponding top bragg mirror 180 is reduced as the logarithm is reduced. At the top Bragg reflector 180 thickThe equivalent series resistance of the top bragg reflector 180 can be correspondingly reduced while the degree H is reduced, the voltage is reduced, and the heat generation amount is reduced. Specifically, the method comprises the following steps: when Al is present _(0.9) Ga _(0.1) As/Al _(0.1) Ga _(0.9) As is adjusted to Al _(0.98) Ga _(0.02) As/Al _(0.1) Ga _(0.9) As, the difference in refractive index between the first refractive index layer and the second refractive index layer is 0.5592.

In one embodiment, as shown in fig. 1, after the epitaxial structure is formed on the substrate 110, the bottom bragg mirror 120 and the active layer 140 may be formed into a step structure by mesa etching, thereby facilitating the lateral oxidation.

In one embodiment, as shown in fig. 1, a first electrode 210 is further disposed on the side of the top bragg mirror 180 away from the oxide confinement layer 160, and a second electrode 220 is disposed on the mesa of the bottom bragg mirror 120 near the active layer 140, thereby connecting the vcsel into the circuit through the first electrode 210 and the second electrode 220.

In one embodiment, as shown in fig. 1, the first electrode 210 is a P-type electrode and the second electrode 220 is an N-type electrode.

In one embodiment, as shown in fig. 1, a contact layer 190 is disposed between the first electrode 210 and the top bragg reflector 180 for better current injection.

In one embodiment, the first electrode 210 is a ring electrode.

In one embodiment, the active layer 140 is a multiple quantum well layer so as to enable a device having a lower threshold, higher quantum efficiency, excellent temperature characteristics, and an extremely narrow line width.

In one embodiment, as shown in fig. 1, a first buffer layer 130 is further disposed between the bottom bragg mirror 120 and the active layer 140, a second buffer layer 150 is further disposed between the active layer 140 and the oxide confinement layer 160, and a third buffer layer 170 is disposed between the oxide confinement layer 160 and the top bragg mirror 180, thereby contributing to an improvement in device performance.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A vertical cavity surface emitting laser is characterized by comprising a substrate, and a bottom Bragg reflector, an active layer, an oxidation limiting layer with a first current window and a top Bragg reflector with a second current window which are sequentially stacked on the substrate, wherein orthographic projections of the first current window and the second current window on the substrate are superposed.

2. A vertical cavity surface emitting laser according to claim 1, wherein said bottom Bragg mirror and/or said top Bragg mirror each include a plurality of first refractive index layers and a plurality of second refractive index layers alternately arranged, the difference in refractive index between said first refractive index layers and said second refractive index layers being greater than 0.5114.

3. A vertical cavity surface emitting laser according to claim 2, wherein the difference in refractive index between said first refractive index layer and said second refractive index layer is 0.5592.

4. A vertical cavity surface emitting laser according to claim 1, wherein said bottom Bragg reflector and said active layer form a stepped structure.

5. A vertical cavity surface emitting laser according to claim 4, wherein a first electrode is further provided on a side of said top Bragg mirror facing away from said oxide confinement layer, and a second electrode is provided on a mesa of said bottom Bragg mirror adjacent to said active layer.

6. A vertical Cavity surface emitting laser according to claim 5 wherein said first electrode is a P-type electrode and said second electrode is an N-type electrode.

7. A vertical cavity surface emitting laser according to claim 5, wherein a contact layer is provided between said first electrode and said top Bragg reflector.

8. A vertical cavity surface emitting laser according to claim 5, wherein said first electrode is a ring electrode.

9. A vertical cavity surface emitting laser according to claim 1, wherein a first buffer layer is further provided between said bottom Bragg reflector and said active layer, and a second buffer layer is further provided between said active layer and said oxide confinement layer.

10. A vertical cavity surface emitting laser according to claim 1, wherein said active layer is a multiple quantum well layer.