CN113964648B - surface emitting semiconductor laser - Google Patents

Abstract

The present invention provides a surface emitting semiconductor laser including: a substrate; a lower distributed feedback mirror located on the substrate; a first isolation layer and a first electrode are arranged on one side of the top surface of the lower distributed feedback reflector, and an active layer, an upper distributed feedback reflector, a second isolation layer and a second electrode are arranged on the other side of the top surface of the lower distributed feedback reflector; the first isolation layer is positioned between the first electrode and the lower distributed feedback reflecting mirror, and the first electrode is intersected with two side surfaces of the first isolation layer; the active layer is positioned between the upper distributed feedback reflector and the lower distributed feedback reflector; the top surface of the upper distributed feedback reflecting mirror comprises a low top surface and a high top surface, the second electrode is arranged on the low top surface, the second isolation layer is arranged between the low top surface and the second electrode, and the second electrode is intersected with two side surfaces of the second isolation layer; and a third isolation layer is arranged around the side surface of the high top surface of the upper distributed feedback reflector, and forms a light outlet around the high top surface of the upper distributed feedback reflector.

Description

surface emitting semiconductor laser

Technical field

The present invention relates to the field of semiconductors, and in particular to a surface-emitting semiconductor laser.

Background technique

In the existing technology, the current of surface-emitting semiconductor lasers flows vertically. In order to improve the conductivity, the distributed feedback mirror needs to be doped, but this will increase the loss of light during the feedback process. On the other hand, the surface-emitting semiconductor laser has a large light exit hole, which causes the mode of the laser light to be multiple transverse modes. When the light output by multiple transverse modes is transmitted in the optical fiber, its inter-mode dispersion is large, and the corresponding transmission distance is reduced. This results in the communication distance of surface-emitting lasers in data centers being limited to 200m. At present, surface-emitting semiconductor lasers mainly achieve single lateral mode by reducing the light exit hole. However, there are two problems in reducing the light exit hole: first, the lateral limitation of current is achieved by lateral oxidation. If the reduction is The light exit hole means that the lateral oxidation will be further intensified and the gain area will be reduced, thus increasing the current threshold that allows the surface-emitting semiconductor laser to laser; secondly, the yield of the single transverse mode of the laser can be achieved through the lateral oxidation process Very low.

In the process of realizing the concept of the present disclosure, the inventor found that there are at least the following problems in the related technology: the distributed feedback mirror needs to be doped, which increases the loss of light in the feedback process; the lasing light emitted by the surface-emitting semiconductor laser is too much Transverse mode, the transmission distance is short; the surface-emitting semiconductor laser realizes the single transverse mode by reducing the light exit hole, and the gain area will be reduced, so that the current threshold that the surface-emitting semiconductor laser can lasing is increased; the laser is realized through the lateral oxidation process The yield of the single transverse mode is very low.

Contents of the invention

To overcome at least one aspect of the above problems, the present disclosure provides a surface-emitting semiconductor laser, including:

substrate;

a lower distributed feedback mirror located on the substrate;

A first isolation layer and a first electrode are provided on one side of the top surface of the lower distributed feedback mirror, and an active layer, an upper distributed feedback mirror, a second isolation layer and a second electrode are provided on the other side;

The first isolation layer is located between the first electrode and the lower distributed feedback mirror, and the first electrode intersects two side surfaces of the first isolation layer;

The active layer is located between the upper distributed feedback mirror and the lower distributed feedback mirror;

The top surface of the upper distributed feedback reflector includes a low top surface and a high top surface. The second electrode is disposed on the low top surface. The second isolation layer is disposed between the low top surface and the second electrode. The second electrode and the second The two sides of the isolation layer intersect;

A third isolation layer is provided around the side where the first electrode and the second electrode are close to each other and the side of the high top surface of the upper distributed feedback reflector. The third isolation layer forms a light outlet around the high top surface of the upper distributed feedback reflector.

According to an embodiment of the present disclosure, the light outlet hole is perpendicular to the top surfaces of the first electrode and the second electrode;

The first electrode and the second electrode are on opposite sides relative to the light outlet;

The top surface of the first electrode is lower than the top surface of the second electrode.

According to an embodiment of the present disclosure, the top surface of the lower distributed feedback mirror includes a low top surface and a high top surface, the active layer is disposed on the high top surface, and the first electrode is disposed on the low top surface.

According to an embodiment of the present disclosure, a first mesa and a second mesa are further included;

The first electrode is completely or partially covered on the first mesa;

The second electrode completely or partially covers the second mesa.

According to an embodiment of the present disclosure, the upper surface and side surfaces of the first isolation layer, and the transversely extending surface of the contact portion of the first electrode and the lower distributed feedback reflector constitute the first mesa;

The upper surface and side surfaces of the second isolation layer, and the transversely extending surface of the contact portion of the second electrode and the upper distributed feedback reflector form the second mesa.

According to an embodiment of the present disclosure, the lower distributed feedback reflector is an N-type distributed feedback reflector, the first mesa is an N-type mesa, and the first electrode includes an N-surface electrode;

The upper distributed feedback reflector is a P-type distributed feedback reflector, the second mesa is a P-type mesa, and the second electrode includes a P-surface electrode.

According to an embodiment of the present disclosure, the lower distributed feedback reflector is a P-type distributed feedback reflector, the first mesa is a P-type mesa, and the first electrode includes a P-surface electrode;

The upper distributed feedback reflector is an N-type distributed feedback reflector, the second mesa is an N-type mesa, and the second electrode includes an N-surface electrode.

According to an embodiment of the present disclosure, the first electrode and the second electrode are in close contact with the third isolation layer.

According to embodiments of the present disclosure, the cross-sectional shape of the light outlet includes a circle, an ellipse, a square or a rectangle.

According to an embodiment of the present disclosure, the first electrode and the second electrode surround the light hole in a semicircular ring shape.

Based on the above technical solutions, it can be seen that the present disclosure has at least the following beneficial effects:

The present disclosure provides a surface-emitting semiconductor laser, including: a substrate; a lower distributed feedback mirror located on the substrate; a first isolation layer and a first electrode are provided on one side of the top surface of the lower distributed feedback mirror, and on the other side An active layer, an upper distributed feedback mirror, a second isolation layer and a second electrode are provided; the first isolation layer is located between the first electrode and the lower distributed feedback mirror, and the first electrode intersects two sides of the first isolation layer ; The active layer is located between the upper distributed feedback reflector and the lower distributed feedback reflector; the top surface of the upper distributed feedback reflector includes a low top surface and a high top surface, the second electrode is set on the low top surface, and the second isolation The layer is disposed between the low top surface and the second electrode, the second electrode intersects two sides of the second isolation layer; the side where the first electrode and the second electrode are close to each other, and the high top surface of the upper distributed feedback mirror A third isolation layer is arranged around the side of the upper distributed feedback reflector, and the third isolation layer forms a light outlet around the high top surface of the upper distributed feedback reflector. Through this arrangement, the electrical limitation is independent of the optical limitation; the current of the present disclosure can flow in the horizontal direction, no doping is required in the upper and lower distributed feedback mirrors, and the loss of light during the feedback process is low; a suitable light outlet hole is set The small size allows the surface-emitting semiconductor laser to achieve a single transverse mode, which does not increase the current threshold of the surface-emitting semiconductor laser and increases the light transmission distance; it does not require the use of side oxidation processes, and the yield is high.

Description of the drawings

For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic cross-sectional structural diagram of a surface-emitting semiconductor laser according to an embodiment of the present disclosure;

FIG. 2 is a schematic three-dimensional structural diagram of a surface-emitting semiconductor laser according to an embodiment of the present disclosure.

[Explanation of reference symbols]

1-Substrate

2-Down type distributed feedback mirror

3-First isolation layer

4-First electrode

5-Active layer

6-Upper distributed feedback mirror

7-Second isolation layer

8-Second electrode

9-Third isolation layer

10-Light hole

11-First countertop

12-Second countertop

Detailed ways

In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the description The embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. The terms "comprising," "comprising," and the like, as used herein, indicate the presence of stated features, steps, operations, and/or components but do not exclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted to have meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

The present invention will be described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the schematic diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which shall not limit the protection of the present invention. range. In addition, the three-dimensional dimensions of length, width and depth should be included in actual production.

The ordinal numbers used in this disclosure, such as "first", "second" and other words, are used to modify the components and parts claimed for protection (such as the first electrode, the first isolation layer, etc.), and they do not themselves include or represent the components. , parts have any previous ordinal numbers, nor does it represent the order of manufacturing methods between a certain part and another part. The use of these ordinal numbers is only used to make one part or part with a certain name and another with the same name Components and parts can be clearly distinguished.

In the context of this disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present between them. element.

FIG. 1 is a schematic cross-sectional structural diagram of a surface-emitting semiconductor laser according to an embodiment of the present disclosure; FIG. 2 is a schematic three-dimensional structural diagram of a surface-emitting semiconductor laser according to an embodiment of the present disclosure. In the prior art, electrodes are generally located on the upper and lower surfaces of the light outlet 10, and the active layer 5 is located below the light outlet 10. Current flows in the vertical direction, and only a small amount of current can flow to the bottom of the light outlet 10, but the light outlet The active layer 5 below 10 is the place where light is emitted, just like the filament in a light bulb. If the current flowing through the filament is very small, the light-emitting efficiency will be very low. In order to ensure that more current can flow through the active layer 5 below the light outlet hole 10, the side-emitting semiconductor laser needs to be oxidized on the side. Side oxidation is to create a current bottleneck above the active layer 5, and the surrounding area is blocked by an isolation layer formed by oxide. Current can only flow downward from the bottleneck in the middle, just like a beer bottle. Current can only flow from the bottleneck. Then it reaches the active layer 5 below the light exit hole 10. In addition, to achieve a single lateral mode, at least the lateral size of the optical cavity must be ensured to be 2um. It is difficult to achieve such high precision in the current lateral oxidation process. As shown in Figures 1 and 2, the present disclosure provides a surface-emitting semiconductor laser, including:

Substrate 1; a lower distributed feedback mirror located on the substrate 1; a first isolation layer 3 and a first electrode 4 are provided on one side of the top surface of the lower distributed feedback mirror, and an active layer 5 and an upper distributed feedback mirror are provided on the other side. Reflector 6, second isolation layer 7 and second electrode 8; the first isolation layer 3 is located between the first electrode 4 and the lower distributed feedback reflector, and the first electrode 4 intersects the two sides of the first isolation layer 3; The active layer 5 is located between the upper distributed feedback mirror 6 and the lower distributed feedback mirror; the top surface of the upper distributed feedback mirror 6 includes a low top surface and a high top surface, and the second electrode 8 is disposed on the low top surface. The second isolation layer 7 is disposed between the low top surface and the second electrode 8, the second electrode 8 intersects the two sides of the second isolation layer 7; the sides of the first electrode 4 and the second electrode 8 that are close to each other, and A third isolation layer 9 is provided around the side of the high top surface of the upper distributed feedback reflector 6 , and the third isolation layer 9 forms a light outlet 10 around the high top surface of the upper distributed feedback reflector 6 .

The upper distributed feedback mirror 6 includes a laterally extending portion in contact with the second isolation layer 7 and the second electrode 8 , and a portion in contact with the third isolation layer 9 , and generally has a shape such as “″”.

The current flows horizontally between the first electrode 4 and the second electrode 8. The current brings gain through the active layer 5 and generates spontaneously radiated photons. In theory, spontaneously radiated photons will appear in all directions, but due to this The distributed feedback mirror of the embodiment only exists in the up and down directions, so photons in the up and down directions can be fed back. When the gain in this direction is equal to the loss, the surface-emitting laser starts lasing at the light exit hole 10 . As shown by the arrows in Figure 1, the light field resonates in the vertical direction inside the laser. The first isolation layer 3, the second isolation layer 7 and the third isolation layer 9 are used to limit the electric field, and the direction of light emission is top light.

In addition, the light outlet hole 10 is perpendicular to the top surfaces of the first electrode 4 and the second electrode 8; the first electrode 4 and the second electrode 8 are on opposite sides relative to the light outlet hole 10; the top surface of the first electrode 4 is lower than the second electrode. 8 top surface.

In the surface-emitting semiconductor laser provided by this embodiment, the light-emitting hole 10 is located at the top of the surface-emitting semiconductor laser, the electrodes are located on the left and right sides of the light-emitting hole 10, and the active layer 5 is located under the light-emitting hole 10. Current can flow in the horizontal direction through In the active layer 5, the current can flow to the bottom of the light outlet hole 10, so there is no need to dope the upper distributed feedback mirror 6 or the lower distributed feedback mirror 2, which reduces the loss of light in the feedback process; in this embodiment The distributed feedback mirror only exists in the up and down direction, which can bring optical feedback in the vertical direction and achieve lateral restriction, so there is no need to use a side oxidation process; by setting the first isolation layer 3, the second isolation layer 7 and the third isolation layer Layer 9 can limit the flow of current; etching the light outlet 10 to an appropriate size will not increase the current threshold of the surface-emitting semiconductor laser, and a single transverse mode surface-emitting semiconductor laser can be obtained with a longer transmission distance. .

As an optional embodiment, the top surface of the lower distributed feedback mirror includes a low top surface and a high top surface, the active layer 5 is disposed on the high top surface, and the first electrode 4 is disposed on the low top surface.

In addition, the surface-emitting semiconductor laser of this embodiment also includes a first mesa 11 and a second mesa 12; the first electrode 4 can be completely or partially covered on the first mesa 11; the second electrode 8 can be completely or partially covered on the second mesa. Countertop 12. FIG. 2 is a schematic diagram of the first electrode 4 and the second electrode 8 partially covering the first mesa 11 and the second mesa 12 respectively.

When the first electrode 4 completely covers the first mesa 11, the contact part between the first electrode 4, the first isolation layer 3 and the lower distributed feedback reflector is the first mesa 11; when the second electrode level completely covers the second mesa On 12 , the contact portion between the second electrode 8 and the second isolation layer 7 and the upper distributed feedback reflector 6 is the second mesa 12 .

When the first electrode 4 partially covers the first mesa 11, the contact portion of the first electrode 4 with the first isolation layer 3 and the lower distributed feedback reflector extends laterally to form the first mesa 11; when the second electrode partially covers the first mesa 11 On the second mesa 12 , the contact portion of the second electrode 8 with the second isolation layer 7 and the upper distributed feedback mirror 6 extends laterally to form the second mesa 12 , and the first mesa 11 includes the contact between the first electrode 4 and the first isolation layer 3 A portion of the transversely extending mesa and a transversely extending mesa at the contact portion of the first electrode 4 and the lower distributed feedback reflector; the second mesa 12 includes a transversely extending mesa at the contact portion between the first electrode and the second isolation layer 7 and the second electrode 8 The contact portion with the upper distributed feedback mirror 6 is a mesa extending laterally.

As shown in FIGS. 1 and 2 , the extension lengths of the first mesa 11 and the second mesa 12 may be equal to the width of the substrate 1 . The first mesa 11 and the second mesa 12 generally present a shape such as a chair. The first mesa The shapes and sizes of 11 and the second mesa 12 can also adopt different solutions according to needs.

In the surface-emitting semiconductor laser of this embodiment, the current flows horizontally between the first mesa 11 and the second mesa 12. The conductivity is very high. There is no need to dope the upper and lower distributed feedback mirrors, which reduces the light feedback process. The loss in the medium improves the gain effect.

As an optional embodiment, the lower distributed feedback mirror is an N-type distributed feedback mirror, the first mesa 11 is an N-type mesa, and the first electrode 4 includes an N-surface electrode; the upper distributed feedback mirror 6 is a P-type distributed feedback mirror. Reflector, the second mesa 12 is a P-type mesa, and the second electrode 8 includes a P-surface electrode.

As an optional embodiment, the lower distributed feedback mirror is a P-type distributed feedback mirror, the first mesa 11 is a P-type mesa, and the first electrode 4 includes a P-surface electrode; the upper distributed feedback mirror 6 is an N-type distributed feedback mirror. Reflecting mirror, the second mesa 12 is an N-shaped mesa, and the second electrode 8 includes an N-surface electrode.

In the surface-emitting semiconductor laser of this embodiment, the light field resonates in the vertical direction inside the laser, and the current flows from the P-surface mesa to the N-type mesa in the horizontal direction. Through the preparation of the mesa and electrodes, the electric field is generated in all directions. limit.

In order to achieve a better current injection effect, the first electrode 4 is in close contact with the first mesa 11; the second electrode 8 is in close contact with the second mesa 12. The first electrode 4 and the second electrode 8 are as close as possible to the light outlet 10, and then by setting the first isolation layer 3, the second isolation layer 7 and the third isolation layer 9, the first electrode 4 and the second electrode 8 are in close contact with each other. The third isolation layer 9 allows current to be injected and flowed out near the light outlet 10 .

In addition, the cross-sectional shape of the light outlet 10 includes a circle, an ellipse, a square or a rectangle. Taking a circle as an example, as shown in FIG. 2 , the first electrode 4 and the second electrode 8 surround the light outlet 10 in a semicircular ring shape, so that current can be injected and flowed out close to the light outlet 10 .

The surface-emitting semiconductor laser provided by the present disclosure does not need to dope the upper and lower distributed feedback mirrors, which reduces the loss of light in the feedback process; it does not need to use a side oxidation process, which reduces the process difficulty and process steps; it can limit the current in Flow in different directions; single transverse mode surface-emitting semiconductor lasers can also be obtained, with longer transmission distances.

It should be noted that Figures 1 and 2 are only examples to which embodiments of the present disclosure can be applied to help those skilled in the art understand the technical content of the present disclosure, but do not mean that the present disclosure is limited to only one structure. For example, the shapes and sizes of the first mesa and the second mesa can be different according to needs. The first electrode can completely or partially cover the first mesa; the second electrode can fully or partially cover the second mesa, etc.

In the above embodiments, each embodiment is described with its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

The above-mentioned specific embodiments further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (9)

1. A surface-emitting semiconductor laser, comprising:

a substrate;

a lower distributed feedback mirror on the substrate;

a first isolation layer and a first electrode are arranged on one side of the top surface of the lower distributed feedback reflector, and an active layer, an upper distributed feedback reflector, a second isolation layer and a second electrode are arranged on the other side of the top surface of the lower distributed feedback reflector;

the upper surface and the side surface of the first isolation layer and the surface of the contact part of the first electrode and the lower distributed feedback reflector, which extends transversely, form a first table top;

the active layer is positioned between the upper distributed feedback mirror and the lower distributed feedback mirror;

the upper surface and the side surface of the second isolation layer and the surface of the contact part of the second electrode and the upper distributed feedback reflector, which extends transversely, form a second table top;

the top surface of the upper distributed feedback reflector comprises a low top surface and a high top surface, and the second electrode is arranged on the low top surface;

and a third isolation layer is arranged around the side surface of the high top surface of the upper distributed feedback reflector, and a light outlet hole is formed around the high top surface of the upper distributed feedback reflector.

2. The surface-emitting semiconductor laser according to claim 1, wherein the light-emitting hole is perpendicular to top surfaces of the first electrode and the second electrode;

the first electrode and the second electrode are positioned at opposite sides relative to the light emergent hole;

the top surface of the first electrode is lower than the top surface of the second electrode.

3. The surface emitting semiconductor laser of claim 1, wherein the lower distributed feedback mirror top surface comprises a low top surface and a high top surface, the active layer is disposed on the high top surface of the lower distributed feedback mirror, and the first electrode is disposed on the low top surface of the lower distributed feedback mirror.

4. The surface-emitting semiconductor laser according to claim 1, wherein:

the first electrode is completely or partially covered on the first table top;

the second electrode is entirely or partially covered on the second mesa.

5. The surface emitting semiconductor laser of claim 1, wherein the lower distributed feedback mirror is an N-type distributed feedback mirror, the first mesa is an N-type mesa, and the first electrode comprises an N-plane electrode;

the upper distributed feedback reflector is a P-type distributed feedback reflector, the second table top is a P-type table top, and the second electrode comprises a P-face electrode.

6. The surface emitting semiconductor laser of claim 1, wherein the lower distributed feedback mirror is a P-type distributed feedback mirror, the first mesa is a P-type mesa, and the first electrode comprises a P-face electrode;

the upper distributed feedback reflector is an N-type distributed feedback reflector, the second table top is an N-type table top, and the second electrode comprises an N-face electrode.

7. The surface emitting semiconductor laser of claim 1, wherein the first electrode and the second electrode are in close proximity to the third isolation layer.

8. The surface-emitting semiconductor laser according to claim 1, wherein a cross-sectional shape of the light-emitting hole includes a circle, an ellipse, a square, or a rectangle.

9. The surface-emitting semiconductor laser according to claim 1, wherein the first electrode and the second electrode surround the light-emitting hole in a semicircular shape.