Horizontal cavity vertical emission laser

Abstract

The utility model relates to the technical field of lasers, and provides a horizontal cavity vertical emitting laser which comprises an epitaxial structure, the epitaxial structure comprises a ridge waveguide area, the top of the epitaxial structure is recessed downwards to form a light reflection area, the light reflection area is located on one side of the ridge waveguide area, and the ridge waveguide area is located on the other side of the light reflection area. The ridge waveguide area is provided with a ridge waveguide and a light emitting end, the light reflecting area is provided with a reflecting surface capable of reflecting laser emitted by the light emitting end into vertical laser, and the light emitting end and the reflecting surface are both located in the recess. According to the utility model, the reflecting surface is arranged on the epitaxial structure, so that laser emitted by the light emitting end can be reflected into vertical laser, and compared with the traditional on-chip and off-chip schemes, the vertical light emitting device has the advantages of low cost, high vertical light emitting efficiency and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of lasers, and specifically relates to a horizontal cavity vertical emission laser. Background Art

[0002] For the infrared band laser light source of 3D structured light, the current mainstream technical solution is to use VCSEL (Vertical-Cavity Surface-Emitting Laser). The biggest problem with this solution is that the working wavelength of the VCSEL used for face recognition is 940nm, and the laser in the near-infrared spectral region band of 750nm to 1400nm is likely to cause eye safety problems. The 940nm wavelength laser will focus on the retina of the human eye and will not trigger the protective blink reflex. This limits the intensity of the laser light source of 3D structured light, affecting the accuracy of face recognition and the anti-environmental light ability based on the structured light solution. And the epitaxial growth of the 1550nm wavelength VCSEL chip, which is safer for the human eye, is difficult and there is no possibility of realization for the time being, which greatly limits the face recognition ability of 3D structured light.

[0003] On the other hand, as a horizontal cavity resonant laser, the DFB (Distributed Feedback Laser) based on the indium phosphide material system has been widely used in the field of optical communication. Its working wavelength covers 1200nm to 1700nm and can work in the wavelength range safe for the human eye. The existing vertical emission solutions based on DFB lasers are divided into on-chip solutions and off-chip solutions. The off-chip solution mainly realizes the vertical deflection of the horizontal beam by rotating the angle or introducing optical components in the package, with a complex structure and high cost; the on-chip solution mainly introduces a high-order grating to realize the vertical deflection of the horizontal beam. The vertical component of the high-order grating structure can be used to realize the vertical deflection of the horizontal beam, but the coupling efficiency of the grating vertical component is low. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a horizontal cavity vertical emission laser, which can at least solve some defects in the prior art.

[0005] To achieve the above object, the embodiments of the present utility model provide the following technical solutions: A horizontal cavity vertical emission laser, comprising an epitaxial structure, the epitaxial structure includes a ridge waveguide region, a light reflection region is recessed downward from the top of the epitaxial structure, the light reflection region is located on one side of the ridge waveguide region, the ridge waveguide region has a ridge waveguide and a light emission end, the light reflection region has a reflection surface that can reflect the laser emitted from the light emission end into a vertical laser, both the light emission end and the reflection surface are located in the recess, the epitaxial structure includes an active layer, the laser is emitted from the active layer, the epitaxial structure further includes an indium phosphide transition layer, a grating layer, a grating buried layer, an etch stop layer, a P-type indium phosphide waveguide layer and an indium gallium arsenide contact layer sequentially stacked on the active layer, the active layer is disposed on a substrate, a step structure is formed at the recess, the step structure is located at the bottom end of the reflection surface, the lowest step of the step structure is set at 90 degrees to the light emission end, and the higher step does not block the horizontal laser.

[0006] Further, the light emission end is vertically arranged, and the reflection surface is inclined at 45 degrees.

[0007] Further, the ridge waveguide is formed on the P-type indium phosphide waveguide layer and the indium gallium arsenide contact layer.

[0008] Further, a P electrode is provided on the ridge waveguide.

[0009] Further, a grating is provided on the grating layer.

[0010] Further, the bottom of the recess sinks into the substrate.

[0011] Further, the reflection surface is a metal layer.

[0012] Further, the wavelength band of the laser emitted by the light emission end is between 1500 and 1700 nm.

[0013] Compared with the prior art, the beneficial effects of the present utility model are:

[0014] 1. A reflection surface is provided on the epitaxial structure, which can reflect the laser emitted from the light emission end into a vertical laser. Compared with the traditional on-chip and off-chip solutions, it has the advantages of low cost and high vertical light output efficiency.

[0015] 2. Compared with the infrared light emitter in the VCSEL solution of the structured light in 3D face recognition, it has a long wavelength working band of 1500 nm to 1700 nm. On the premise of eye safety, it can improve the output optical power, enhance the anti-interference ability of face recognition, be insensitive to ambient light, and have higher recognition accuracy. Description of the Drawings

[0016] Figure 1The front view of an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0017] Figure 2 The perspective view of an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0018] Figure 3 The top view of a ridge waveguide continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0019] Figure 4 The perspective view of a ridge waveguide continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0020] Figure 5 The front view of a parallelepiped continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0021] Figure 6 The perspective view of a parallelepiped continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0022] Figure 7 The front view of a vertical light emitting end (light emitting cavity surface) continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0023] Figure 8 The perspective view of a vertical light emitting end (light emitting cavity surface) continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0024] Figure 9 The front view of a passivation layer and an antireflection film continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0025] Figure 10 The perspective view of a passivation layer and an antireflection film continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0026] Figure 11 The front view of a P electrode and a metal layer continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention; ]

[0027] Figure 12 The perspective view of a P electrode and a metal layer continuously shown on an epitaxial structure of a horizontal cavity vertical emission laser provided by an embodiment of the present invention;

[0028] Figure 13Schematic diagram of laser reflection of a horizontally-cavity vertical-emission laser provided by an embodiment of the present invention;

[0029] In the attached drawings: 1 - substrate; 2 - active layer; 3 - indium phosphide transition layer; 4 - grating layer; 5 - grating buried layer; 6 - etch stop layer; 7 - P-type indium phosphide waveguide layer and indium gallium arsenide contact layer; 8 - passivation layer and antireflection film; 9 - P electrode; 10 - metal layer; 11 - N electrode; 12 - high-reflection coating layer; 13 - N substrate; 14 - laser. Detailed implementation manners

[0030] 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 described embodiments are only a part rather than all of the embodiments of the present invention.Any other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention shall fall within the protection scope of the present invention.

[0031] Please refer to Figures 1 to 12 , an embodiment of the present invention provides a preparation method of a horizontally-cavity vertical-emission laser, including the following steps: S1, fabricating an epitaxial structure; S2, fabricating a ridge waveguide on the epitaxial structure; S3, growing a mask layer to protect the area where the ridge waveguide is located; S4, etching the area other than the ridge waveguide on the epitaxial structure to fabricate an inclined surface with a 45-degree inclination angle and expose the light-emitting end of the epitaxial structure, where the light-emitting end faces the inclined surface; S5, fabricating a reflecting surface on the inclined surface, and the horizontally emitted laser from the light-emitting end is incident on the reflecting surface, and the reflecting surface reflects the horizontally emitted laser into a vertically emitted laser and emits it outside the epitaxial structure. Fabricating a reflecting surface on the epitaxial structure can reflect the laser emitted from the light-emitting end into a vertically emitted laser, which has advantages such as low cost and high vertical light-emitting efficiency compared with traditional on-chip and off-chip solutions. As Figure 13 shown, the horizontally emitted laser can be reflected by the reflecting surface and then emitted as a vertically emitted laser. Preferably, the etching is performed by using an IBE (ion beam etching) method to etch the epitaxial structure to form the inclined surface.

[0032] As an optimized solution of the embodiment of the present invention, please refer to Figures 1 to 12 , during etching, first etch downward on the epitaxial structure to form a notch of a parallelepiped, and the epitaxial structure forms parallel inclined surfaces and a light-emitting end at the notch, and then etch the light-emitting end into a vertical light-emitting cavity surface. In this embodiment, the etching is performed by using an IBE etching method, and the etching can be performed by means of tilting and rotating the sample stage to form a notch resembling a parallelepiped, where both the light-emitting end and the inclined surface are inclined at 45 degrees. Preferably, the etching depth is between 10 and 50 μm, that is, the height of the parallelepiped is between 10 and 50 μm.

[0033] As an optimized solution of the embodiment of the present utility model, please refer to Figures 1 to 12 . The specific method for fabricating the reflective surface is as follows: A passivation layer and an antireflection film 8 are grown on the inclined surface, and then a metal layer 10 is fabricated on the passivation layer and the antireflection film 8, and the metal layer 10 serves as the reflective surface. In this embodiment, the metal layer 10 can be a thin Au metal layer.

[0034] As an optimized solution of the embodiment of the present utility model, please refer to Figures 1 to 12 . A P electrode 9 is fabricated on the ridge waveguide, and there is a gap between the reflective surface and the P electrode 9. In this embodiment, the reflective surface is not connected to the P electrode 9.

[0035] As an optimized solution of the embodiment of the present utility model, please refer to Figures 1 to 12 . The epitaxial structure includes an active layer 2, an indium phosphide transition layer, a grating layer 4, a grating buried layer 5, an etch stop layer 6, a P-type indium phosphide waveguide layer, and an indium gallium arsenide contact layer 7 grown in sequence on a substrate 1. Preferably, the P-type indium phosphide waveguide layer and the indium gallium arsenide contact layer are etched to form a ridge waveguide. In step S4, the etching is performed to the substrate 1 layer.

[0036] The following are the specific implementation manners:

[0037] (1) Using MOCVD (metalorganic chemical vapor deposition), an active layer 2, an indium phosphide transition layer 3, and a grating layer 4 are grown in sequence on an indium phosphide substrate 1. The grating is fabricated using EBL technology and etching technology, and then the grating buried layer 5, the etch stop layer 6, the P-type indium phosphide waveguide, and the indium gallium arsenide contact layer 7 are continuously buried and grown using MOCVD, as shown in Figure 1 、 Figure 2 ;

[0038] (2) Using photolithography technology and etching technology, the P-type indium phosphide waveguide and the indium gallium arsenide contact layer 7 are etched into a ridge waveguide using a phosphoric acid-based etching solution, as shown in Figure 3 、 Figure 4 ;

[0039] (3) Then, a mask layer is grown using PECVD (plasma enhanced chemical vapor deposition). Using photolithography and etching processes, the mask layer in the ridge waveguide region is retained, and then the region outside the mask layer in the ridge waveguide region is etched to the indium phosphide substrate 1 using IBE etching technology. The IBE etching technology can tilt and rotate the sample stage so that the Ar+ ion beam generated by IBE forms a certain angle with the wafer surface. In this embodiment, the optimal angle is 45° obliquely and the etching depth is 10 - 50 μm. Then, the mask layer is removed, as shown in Figure 5 、 Figure 6 ;

[0040] (4) Use PECVD to grow the mask layer again. By using photolithography and etching processes, retain the mask layer in the ridge waveguide region and the mirror region. Then, use etching technology to etch the IBE etching slope near the ridge waveguide into the indium phosphide substrate 1. The etching depth should be greater than the IBE etching depth of S3 to form a groove-shaped etching region. Keep the light-emitting cavity surface perpendicular, and then remove the mask layer, as Figure 7 、 Figure 8 shown;

[0041] (5) Then use PECVD to grow the passivation layer and the anti-reflection film 8 in the light-emitting direction. By using photolithography and etching processes, open the P electrode contact, as Figure 9 、 Figure 10 shown;

[0042] (6) Fabricate the P electrode pad 9 on the ridge waveguide. Then, fabricate a thin Au metal layer 10 on the reflection slope as the reflecting surface of the mirror to reflect the laser 14 emitted by the laser in the vertical direction. Note that the Au metal thin layer 10 and the P electrode pad 9 cannot be connected, as Figure 11 、 Figure 12 shown;

[0043] (7) Then thin the wafer, fabricate the N electrode 11, alloy, then separate the bars, fabricate the high-reflection coating layer 12 using a dielectric film coating equipment, and separate the individual devices to complete the fabrication of the laser. Finally, perform chip packaging by attaching the laser to the N-type substrate 13, as Figure 13 Schematic diagram of the reflecting surface effect.

[0044] An embodiment of the present invention provides a horizontal cavity vertical emission laser fabricated by the above method. Specifically, please refer to Figure 12 , the horizontal cavity vertical emission laser includes an epitaxial structure. The epitaxial structure includes a ridge waveguide region, and a light reflection region is formed by a depression downward from the top of the epitaxial structure. The light reflection region is located on one side of the ridge waveguide region. The ridge waveguide region has a ridge waveguide and a light emission end. The light reflection region has a reflecting surface that can reflect the laser emitted by the light emission end into a vertical laser. Both the light emission end and the reflecting surface are located in the depression. In this embodiment, the epitaxial structure can be divided into a ridge waveguide region and a light reflection region. A ridge waveguide is provided in the ridge waveguide region and a P electrode 9 is provided on the ridge waveguide. A light emission end or a light-emitting cavity surface, and a reflecting surface are formed in the light reflection region. A notch is formed by a depression downward in the light reflection region, and the notch is obtained by the above-described etching method. The structure of the present horizontal cavity vertical emission laser does not limit the preparation process, and other methods except etching can be used in the present horizontal cavity vertical emission laser. This embodiment does not make any limitations in this regard.

[0045] As an optimized solution of the embodiment of the present invention, please refer to Figure 12, the light emitting end is vertically arranged, and the reflecting surface is inclined at 45 degrees. In this embodiment, the light emitting end, or the light emitting cavity surface, is vertically arranged to facilitate the active layer 2 to emit horizontal laser light, and then the vertically inclined laser light can be obtained by reflecting from the 45-degree inclined reflecting surface. Of course, in this embodiment, the direction of the laser light emitted from the light emitting end may not be limited, and we can correspondingly design the inclination angle of the reflecting surface to obtain vertical laser light as well.

[0046] As an optimized solution of the embodiment of the present utility model, please refer to Figure 12 , the epitaxial structure includes an active layer 2, and the laser light is emitted from the active layer 2. In this embodiment, since the laser light is emitted from the active layer 2, this surface of the active layer 2 is the light emitting cavity surface.

[0047] As an optimized solution of the embodiment of the present utility model, please refer to Figure 12 , the epitaxial structure further includes an indium phosphide transition layer 3, a grating layer 4, a grating buried layer 5, an etch stop layer 6, a P-type indium phosphide waveguide layer, and an indium gallium arsenide contact layer 7 which are sequentially stacked on the active layer 2, and the active layer 2 is disposed on the substrate 1. Preferably, a ridge waveguide is formed on the P-type indium phosphide waveguide layer and the indium gallium arsenide contact layer 7. A P electrode 9 is provided on the ridge waveguide. A grating is provided on the grating layer 4. The bottom of the depression sinks into the substrate 1. As shown in Figure 12 , it can be seen that the depth of the downward depression reaches the substrate 1, and then a step structure can be formed at the depression by the above-mentioned etching process. This step structure is located at the bottom end of the reflecting surface. The lowest step of this step structure is arranged at 90 degrees with the light emitting end, and the higher step cannot block the horizontal laser light, and the horizontal laser light needs to be incident on the reflecting surface. Preferably, the wavelength band of the laser light emitted by the light emitting end is between 1500 and 1700 nm, which can improve the output optical power on the premise of eye safety, enhance the anti-interference ability of face recognition, be insensitive to ambient light, and have higher recognition accuracy.

[0048] Although the embodiments of the present utility model have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A horizontal cavity vertical emission laser, comprising an epitaxial structure, characterized in that, The epitaxial structure includes a ridge waveguide region, and a light reflection region is formed by being recessed downward from the top of the epitaxial structure. The light reflection region is located on one side of the ridge waveguide region. The ridge waveguide region has a ridge waveguide and a light emission end. The light reflection region has a reflection surface that can reflect the laser emitted from the light emission end into a vertical laser. Both the light emission end and the reflection surface are located in the recess. The epitaxial structure includes an active layer, and the laser is emitted from the active layer. The epitaxial structure further includes an indium phosphide transition layer, a grating layer, a grating buried layer, an etch stop layer, a P-type indium phosphide waveguide layer, and an indium gallium arsenide contact layer that are sequentially stacked on the active layer. The active layer is disposed on a substrate, and a step structure is formed at the recess. The step structure is located at the bottom end of the reflection surface. The lowest step of the step structure is disposed at a 90-degree angle to the light emission end, and the higher step does not block the horizontal laser.

2. The horizontal cavity vertical emission laser according to claim 1, characterized in that: The light emission end is vertically disposed, and the reflection surface is inclined at 45 degrees.

3. The horizontal cavity vertical emission laser according to claim 1, wherein: The ridge waveguide is formed on the P-type indium phosphide waveguide layer and the indium gallium arsenide contact layer.

4. The horizontal cavity vertical emission laser according to claim 1, characterized in that: A P electrode is disposed on the ridge waveguide.

5. The horizontal cavity vertical emission laser according to claim 1, characterized in that: A grating is disposed on the grating layer.

6. The horizontal cavity vertical emission laser according to claim 1, wherein: The bottom of the recess sinks into the substrate.

7. The horizontal cavity vertical emission laser according to claim 1, wherein: The reflection surface is a metal layer.

8. The horizontal cavity vertical emission laser according to claim 1, wherein: The wavelength band of the laser emitted by the light emission end is between 1500 and 1700 nm.

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