CN113572025B

CN113572025B - Passive section ridge waveguide structure, manufacturing method thereof and laser

Info

Publication number: CN113572025B
Application number: CN202111121270.4A
Authority: CN
Inventors: 朱尧; 周志强; 王丹; 王任凡
Original assignee: Wuhan Minxin Semiconductor Co ltd
Current assignee: Wuhan Minxin Semiconductor Co ltd
Priority date: 2021-09-24
Filing date: 2021-09-24
Publication date: 2021-12-28
Anticipated expiration: 2041-09-24
Also published as: CN113572025A

Abstract

The application provides a passive segment ridge waveguide structure, a manufacturing method thereof and a laser, wherein the passive segment ridge waveguide structure comprises a first waveguide, a second waveguide and an extension waveguide; the first waveguide comprises a light inlet end and a light outlet end, and the second waveguide is positioned on one side of the first waveguide close to the light outlet end, so that part of light beams entering from the light inlet end sequentially pass through the light outlet end and the second waveguide to be transmitted out of the passive section ridge waveguide structure; the expansion waveguide is arranged on the outer periphery side of the second waveguide, and the cross section of the first waveguide is gradually reduced along the direction towards the second waveguide, so that part of light beams entering from the light inlet end are transmitted to the outside of the passive section ridge waveguide structure through the second waveguide. The manufacturing method comprises the steps of manufacturing a mask, covering the mask on a base material, and etching a first waveguide, a second waveguide and at least one expansion waveguide on the base material through dry etching and wet etching.

Description

Passive section ridge waveguide structure, manufacturing method thereof and laser

Technical Field

The application belongs to the technical field of photoelectrons, and particularly relates to a passive section ridge waveguide structure, a manufacturing method thereof and a laser.

Background

The edge-emitting semiconductor laser has the advantages of small volume, light weight, high electro-optic conversion efficiency, stable performance, high reliability, long service life and the like, and is widely applied to the fields of optical fiber communication, optical sensing, laser radar and the like.

However, due to the characteristics of light emission from the end face of the ridge wave in the passive band in the prior art, the light-emitting aperture is small, and the structures in the vertical direction and the horizontal direction are not consistent, the light beam divergence angle is large, the difference between the light beam divergence angle and the aperture of the optical fiber is large, and the direct realization of high-efficiency light field coupling is difficult.

Disclosure of Invention

Therefore, an object of the present invention is to provide a passive ridge waveguide structure and a laser, which can reduce the divergence angle of output light beams and achieve high-efficiency optical field coupling. Meanwhile, the manufacturing method of the passive section ridge waveguide structure is used for manufacturing the passive section ridge waveguide structure which can reduce the divergence angle of output light beams and realize high-efficiency optical field coupling.

In order to solve the above problems, the present application provides a passive segment ridge waveguide structure, comprising a first waveguide, a second waveguide, and at least one extension waveguide; the first waveguide comprises a light inlet end and a light outlet end, and the second waveguide is positioned on one side of the first waveguide close to the light outlet end, so that part of light beams entering from the light inlet end sequentially pass through the light outlet end and the second waveguide to be transmitted to the outside of the passive section ridge waveguide structure; at least one expansion waveguide is arranged on the outer periphery side of the second waveguide, and the cross section of the first waveguide is gradually reduced along the direction towards the second waveguide, so that part of light beams entering from the light inlet end can propagate to the outside of the passive section ridge waveguide structure through the second waveguide.

Optionally, the second waveguide is connected to the light exit end, and the contact surfaces of the second waveguide and the light exit end coincide with each other, and the first waveguide and the second waveguide extend in the same direction.

Optionally, the number of the expansion waveguides is two, the two expansion waveguides are arranged in parallel, and the two expansion waveguides are symmetrically arranged on the outer periphery side of the second waveguide with respect to the second waveguide.

Optionally, the extension waveguide is arranged in parallel with the second waveguide.

Optionally, the first waveguide is a hexahedron, the outer wall between the light inlet end and the light outlet end is a first outer wall, a second outer wall, a third outer wall and a fourth outer wall, the first outer wall and the second outer wall are arranged oppositely, the first outer wall and the second outer wall are folded towards the center of the first waveguide along the direction of the second waveguide, so that part of light beams entering from the light inlet end are transmitted into the second waveguide, and the third outer wall and the fourth outer wall are arranged oppositely and in parallel.

Optionally, the first outer wall, the second outer wall, the third outer wall, and the fourth outer wall are all planar, the first waveguide and the second waveguide extend along a first direction, and a length of an entirety formed by the first waveguide and the second waveguide along the first direction is 15 to 60 μm.

Optionally, the length of the first waveguide along the first direction is 5 to 20 μm, the length of the second waveguide along the first direction is 10 to 40 μm, the extension waveguide extends along the first direction, and the length of the extension waveguide along the first direction is 10 to 40 μm.

Optionally, the first waveguide, the second waveguide, and the extension waveguide are located in a first plane, a projection length of the light entrance end in the first plane is 1.5 to 2.5 μm, a projection length of the light exit end in the first plane is 0.5 to 1.2 μm, a projection of the second waveguide and the extension waveguide in the first plane is a rectangle, and a width of the rectangle is 0.5 to 1.2 μm.

Optionally, the extension waveguide and the second waveguide are arranged apart from each other, and a gap of 0.5 to 2 μm is formed between the extension waveguide and the second waveguide.

In another aspect of the present application, a method for manufacturing a passive segment ridge waveguide structure is provided, including:

manufacturing a mask;

covering the mask on a substrate;

etching a first waveguide, a second waveguide and at least one extension waveguide on the base material through dry etching and wet etching, etching the second waveguide on one side of a light outlet end of the first waveguide, etching the first waveguide to have a gradually decreasing cross section along a direction towards the second waveguide, and etching at least one extension waveguide on the outer peripheral side of the second waveguide.

In another aspect of the present application, a laser is provided, which includes the above-mentioned passive section ridge waveguide structure, the laser includes a passive section and an active section, the passive section is connected with the active section, and the passive section ridge waveguide structure is a part of the passive section.

Optionally, the active segment includes an active segment ridge waveguide, the active segment ridge waveguide is connected to the light inlet end of the first waveguide, and the active segment ridge waveguide and the first waveguide extend along a first direction.

Optionally, the laser further includes an antireflection film and a reflective film, the antireflection film is covered on one end of the passive section far away from the active section, and the reflective film is covered on one end of the active section far away from the passive section.

Advantageous effects

The passive segment ridge waveguide structure and the laser provided by the embodiment of the invention can reduce the divergence angle of output light beams and realize high-efficiency light field coupling. Meanwhile, the manufacturing method of the passive section ridge waveguide structure is used for manufacturing the passive section ridge waveguide structure which can reduce the divergence angle of output light beams and realize high-efficiency optical field coupling.

Drawings

Fig. 1 is a schematic perspective view of a laser according to an embodiment of the present disclosure;

FIG. 2 is a cross-sectional view of a laser according to an embodiment of the present application;

FIG. 3 is a left side view of a laser according to an embodiment of the present application;

FIG. 4 is a right side view of a laser according to an embodiment of the present application;

FIG. 5 is a diagram of the transverse mode field distribution of the active section of a laser according to an embodiment of the present application;

FIG. 6 is a transverse mode field distribution diagram of the output facet of the passive section of a laser according to an embodiment of the present application;

FIG. 7 is an active segment end-facet mode field profile of a laser according to an embodiment of the present application;

fig. 8 is a horizontal far field distribution diagram of the output of the active section and the passive section of the laser according to the embodiment of the present application.

The reference numerals are represented as:

1. a substrate; 2. a buffer layer; 3. a grating layer; 4. a second confinement layer; 5. a lower waveguide layer; 6. a quantum well layer; 7. an upper waveguide layer; 8. a first confinement layer; 9. an etch stop layer; 10. an active segment ridge waveguide; 11. an ohmic contact layer; 12. an electrode; 13. a passive waveguide layer; 14. a first waveguide; 15. a second waveguide; 16. an extension waveguide; 17. an anti-reflection film; 18. a reflective film.

Detailed Description

Referring collectively to fig. 1-4, in accordance with an embodiment of the present application, a passive segment-ridge waveguide structure includes a first waveguide 14, a second waveguide 15, and at least one expansion waveguide 16; the first waveguide 14 comprises a light inlet end and a light outlet end, and the second waveguide 15 is positioned on one side of the first waveguide 14 close to the light outlet end, so that part of light beams entering from the light inlet end sequentially pass through the light outlet end and the second waveguide 15 to be transmitted out of the passive section ridge waveguide structure; at least one expansion waveguide 16 is arranged on the outer periphery of the second waveguide 15, the cross section of the first waveguide 14 decreases gradually along the direction towards the second waveguide 15, so that part of light beams entering from the light inlet end are transmitted to the outside of the passive section ridge waveguide structure through the second waveguide 15, the cross section of the first waveguide 14 decreases gradually along the direction towards the second waveguide 15 by arranging the first waveguide 14, and further, part of the light beams transmitted in the first waveguide 14 can be transmitted into the expansion waveguide 16 arranged along the outer periphery of the second waveguide 15 and transmitted to the outside of the passive section ridge waveguide structure through the expansion waveguide 16, so that the near field of the output light field of the passive section ridge waveguide structure can be effectively expanded, the far field divergence angle is obviously narrowed, the divergence angle is further reduced, the difference between the divergence angle and the light aperture is reduced, and the high-efficiency light field coupling can be realized.

Further, when light is transmitted in the waveguide, according to the coupled wave theory, light energy is transmitted at a place where the refractive index is high, when the light field is transmitted from the active section to the passive section, the light field is concentrated towards the center along with the decreasing of the cross section of the first waveguide 14, when the limit value is reached, the light field is transmitted into the expansion waveguide 16 through the outer peripheral wall of the first waveguide 14, and due to the existence of the expansion waveguide 16, after passing through the expansion waveguide 16, the light field is coupled in the direction perpendicular to the transmission direction, as can be seen from fig. 5 to 8, when the light reaches the output end face, the size of the light spot is effectively increased, the near-field light spot is expanded, and the far-field divergence angle is reduced.

Further, the second waveguide 15 is elongated, and the outer periphery of the second waveguide 15 is the outer periphery centered on the longitudinal direction of the second waveguide 15. The outer periphery of the second waveguide 15 is also understood to mean that the light beam propagates through the second waveguide 15, and the outer wall of the second waveguide 15 that surrounds the light propagation direction is the outer periphery.

The second waveguide 15 is connected with the light-emitting end, the contact surfaces of the second waveguide 15 are overlapped, and the first waveguide 14 and the second waveguide 15 extend in the same direction, so that light beams in the first waveguide 14 can be stably transmitted into the second waveguide 15.

Further, the first waveguide 14 and the second waveguide 15 extend along a straight line.

Further, the first waveguide 14 is disposed opposite to the second waveguide 15 in the extending direction.

The number of the expansion waveguides 16 is two, the two expansion waveguides 16 are arranged in parallel, the two expansion waveguides 16 are symmetrically arranged on the outer periphery side of the second waveguide 15 relative to the second waveguide 15, so that the light fields are coupled towards two opposite sides, when reaching the output end face, the size of the light spot in the direction of the two expansion waveguides 16 is effectively increased, the light spot in the near field is expanded, and the divergence angle of the far field in the direction of the two expansion waveguides 16 is reduced.

The extension waveguide 16 and the second waveguide 15 are arranged in parallel, so that the passive section light field is extended in two opposite directions, namely, the passive section light field is extended towards two sides, the light field is coupled towards two sides, the size of a light spot of the passive section end surface mode field is obviously increased relative to that of the active section end surface mode field, a light spot of a near field is extended, a far field divergence angle is reduced, and the difference between the far field divergence angle and the light aperture is further reduced.

Furthermore, two extension waveguides 16 are located on the same horizontal plane, that is, two extension waveguides 16 are horizontally arranged, so that the passive section light field is simultaneously extended towards two sides in the horizontal direction, the light field is coupled towards two sides in the horizontal direction, the light spot size of the passive section end surface mode field is obviously increased relative to that of the active section end surface mode field, the light spot of the near field is extended, the horizontal divergence angle of the far field is reduced, and the difference between the light spot size and the light aperture is further reduced.

The first waveguide 14 is a hexahedron, the outer wall between the light inlet end and the light outlet end is a first outer wall, a second outer wall, a third outer wall and a fourth outer wall, the first outer wall and the second outer wall are arranged oppositely, the first outer wall and the second outer wall are folded towards the center of the first waveguide 14 along the direction towards the second waveguide 15, so that part of light beams entering from the light inlet end are transmitted into the second waveguide 15, and the third outer wall and the fourth outer wall are arranged oppositely and parallelly to ensure that the light beams enter the expansion waveguide after passing through the first outer wall and the second outer wall. The third outer wall and the fourth outer wall are arranged oppositely and parallelly, so that the light beam is prevented from leaking to the side where the third outer wall is located and the side where the fourth outer wall is located.

Further, any horizontal section of the first waveguide 14 is an isosceles trapezoid.

Further, first outer wall and the vertical setting of second outer wall, and be the angle setting each other. The third outer wall and the fourth outer wall are horizontally arranged oppositely.

Further, the distance between the end of the first outer wall close to the second waveguide 15 and the end of the second outer wall close to the second waveguide 15 is smaller than the distance between the end of the first outer wall far from the second waveguide 15 and the end of the second outer wall far from the second waveguide 15.

Further, the first outer wall and the second outer wall are symmetrically arranged. The third outer wall and the fourth outer wall are symmetrically arranged.

The first outer wall, the second outer wall, the third outer wall and the fourth outer wall are all planes, the first waveguide 14 and the second waveguide 15 extend along the first direction, and the length of the whole formed by the first waveguide 14 and the second waveguide 15 along the first direction is 15-60 micrometers.

In one embodiment, the first waveguide 14 and the second waveguide 15 form an ensemble having a length of 60 μm in the first direction.

The length of the first waveguide 14 along the first direction is 5-20 μm, the length of the second waveguide 15 along the first direction is 10-40 μm, the extension waveguide 16 extends along the first direction, and the length of the extension waveguide 16 along the first direction is 10-40 μm.

Further, the length of the second waveguide 15 in the first direction is equal to the length of the extension waveguide 16 in the first direction.

In one embodiment, the first waveguide 14, the second waveguide 15, and the expansion waveguide 16 each have a length of 30 μm in the first direction.

The first waveguide 14, the second waveguide 15 and the extension waveguide 16 are located in a first plane, the length of the projection of the light inlet end in the first plane is 1.5-2.5 μm, the length of the projection of the light outlet end in the first plane is 0.5-1.2 μm, the projection of the second waveguide 15 and the extension waveguide 16 in the first plane is rectangular, and the width of the rectangle is 0.5-1.2 μm. Because the first outer wall, the second outer wall, the third outer wall and the fourth outer wall are all planes, the length range, the width range of the light inlet end and the width range of the light outlet end of the first waveguide 14 are determined, namely the gradual change angle of the first waveguide 14 is determined, and the stability of adjusting the gradual change light field is improved by the proper gradual change angle.

Further, the length of the projection of the light entrance end in the first plane is the width of the light entrance end. The length of the projection of the light-emitting end in the first plane is the width of the light-emitting end. The width of the rectangle is the width of the second waveguide 15 and the extension waveguide 16.

In one embodiment, the width of the light entrance end is 1.6 μm, the width of the light exit end is 1 μm, and the widths of the second waveguide 15 and the extension waveguide 16 are 1 μm.

The expansion waveguide 16 and the second waveguide 15 are arranged apart from each other, and a gap of 0.5-2 μm is arranged between the expansion waveguide 16 and the second waveguide 15, so that the light beam in the first waveguide 14 can accurately enter the expansion waveguide 16. The expansion size of the light field to two sides can be controlled by setting the gap distance, and the size of the mode field can be adjusted through different gaps. By setting the gap to 0.5 to 2 μm, it is ensured that the distance between the extension waveguide 16 and the second waveguide 15 is not excessively close or excessively far, and occurrence of multiple transverse modes due to excessively close is prevented, and loss of the extension effect due to excessively far is also prevented.

In one embodiment, a 1.2 μm gap is provided between the expansion waveguide 16 and the second waveguide 15.

In another aspect of the present embodiment, a method for manufacturing a passive segment ridge waveguide structure is provided, including:

manufacturing a mask;

covering the mask on the substrate;

the first waveguide 14, the second waveguide 15 and at least one extension waveguide 16 are etched on the base material through dry etching and wet etching, the second waveguide 15 is etched on one side of the light outlet end of the first waveguide 14, the first waveguide is etched to have a gradually decreasing cross section along the direction towards the second waveguide 15, and the at least one extension waveguide 16 is etched on the outer periphery side of the second waveguide 15.

By etching the first waveguide 14 and etching the first waveguide 14 to decrease the cross section along the direction toward the second waveguide 15, a part of light beams propagating in the first waveguide 14 can propagate into the expansion waveguide 16 arranged along the outer periphery of the second waveguide 15 and propagate to the outside of the passive section ridge waveguide structure through the expansion waveguide 16, a near-field light field of an output light field of the passive section ridge waveguide structure can be effectively expanded, the far-field divergence angle is obviously narrowed, the divergence angle is further reduced, the difference between the divergence angle and the light aperture is reduced, and high-efficiency light field coupling can be realized.

Further, the substrate is made of a material of a passive section ridge waveguide structure. When the passive section ridge waveguide structure is part of a laser, the passive section ridge waveguide structure is fabricated on the output of the laser.

Further, the first waveguide 14, the second waveguide 15, and the extension waveguide 16 may be simultaneously formed by etching.

Further, the mask is an SiN mask, firstly, an SiN film is deposited on the surface of the wafer through PECVD, after mask patterns are manufactured through photoetching, the SiN film is etched through RIE to manufacture SiN mask patterns, photoresist is removed, and manufacturing of the SiN mask patterns is completed.

In another aspect of this embodiment, a laser is provided, which includes the above-mentioned passive section ridge waveguide structure, the laser includes a passive section and an active section, the passive section is connected with the active section, and the passive section ridge waveguide structure is a part of the passive section.

The conventional laser has a large beam divergence angle due to a passive section ridge waveguide structure, has a large difference with the aperture of an optical fiber, is difficult to directly realize high-efficiency light field coupling, and usually needs a special lens for coupling during packaging, so that the packaging cost of an optical device and a module is greatly increased. In addition, in order to improve the far-field characteristics of the output beam of the semiconductor laser, the methods mainly adopted in the prior art include end face integrated spot size converters, thick waveguide structure, double-layer waveguide structure and the like, or a buried heterojunction structure is adopted to reduce the far-field divergence angle of the laser. However, the difficulty in the epitaxial process for manufacturing the laser is increased by manufacturing a thick waveguide, a double-layer waveguide or a buried heterojunction structure, so that the chip cost is increased and the yield is reduced. In the laser provided in this embodiment, the first waveguide 14 is disposed in the passive ridge waveguide structure, and the cross section of the first waveguide 14 decreases in the direction toward the second waveguide 15, so that a part of light beams propagating in the first waveguide 14 can propagate into the expansion waveguide 16 disposed along the outer circumferential side of the second waveguide 15, and propagate outside the passive ridge waveguide structure through the expansion waveguide 16, a near-field light field of an output light field of the laser can be effectively expanded, a far-field divergence angle is significantly narrowed, a direction divergence angle of the laser is reduced, a difference between the light beam aperture and the light beam aperture is reduced, high-efficiency light field coupling can be realized, costs generated during packaging are reduced, difficulty in optical alignment during packaging is reduced, coupling efficiency is improved, process manufacturing is simple, no complex epitaxial structure needs to be added, and a large tolerance is provided in an alignment process with a single-mode optical fiber, the manufacturing difficulty is reduced, and the yield is improved.

Furthermore, the passive section ridge waveguide structure is arranged in the passive section, so that no current is injected, no waveguide is narrowed, the chip resistance is increased, and a series of reliability problems caused by high carrier concentration are solved.

The active section comprises an active section ridge waveguide 10, the active section ridge waveguide 10 is connected with a light inlet end of a first waveguide 14, the active section ridge waveguide and the first waveguide 14 extend along a first direction, light gain is realized by current injected into the active section, the active section ridge waveguide 10 is connected with the light inlet end of the first waveguide 14, the active section ridge waveguide and the first waveguide 14 extend along the first direction, and light beams can be ensured to accurately enter the passive section.

Further, the length of the active segment along the first direction is 120-2000 μm, and specifically, in this embodiment, the length of the active segment along the first direction is 160 μm.

Further, the active segment ridge waveguide 10 is connected with the light inlet end of the first waveguide 14 by a butt-joint growing method.

The laser also comprises an antireflection film 17 and a reflecting film 18, wherein the antireflection film 17 is covered at one end of the passive section far away from the active section, and the reflecting film 18 is covered at one end of the active section far away from the passive section. The light emitted by the active section can be reflected into the passive section by arranging the reflecting film 18, and the light beam is prevented from leaking. By arranging the antireflection film 17, reflected light can be reduced, light transmittance can be increased, and stray light can be reduced.

Furthermore, the antireflection film 17 is connected with all the dielectric layers of the passive section, and the reflection film 18 is connected with all the dielectric layers of the active section.

Furthermore, an antireflection film 17 is plated at one end of the passive section far away from the active section, and a reflection film 18 is plated at one end of the active section far away from the passive section.

Further, the reflection film 18 is a high reflection film, and the reflectivity of the reflection film 18 is 85% -95%.

Further, the reflectivity of the antireflection film 17 is 0.1% -0.5%.

The active section further comprises a lower waveguide layer 5, a quantum well layer 6 and an upper waveguide layer 7 which are sequentially overlapped, the passive section comprises a passive waveguide layer 13, the end part of the whole formed by the lower waveguide layer 5, the quantum well layer 6 and the upper waveguide layer 7 is connected with the end part of the passive waveguide layer 13, and the lower waveguide layer 5, the quantum well layer 6, the upper waveguide layer 7 and the passive waveguide layer 13 extend along the first direction. The lower waveguide layer 5 and the upper waveguide layer 7 are capable of confining the optical field to the quantum well region.

Further, the quantum well layer 6 and the passive waveguide layer 13 are grown on the same layer in a butt-joint growth mode, and material refractive index matching is achieved.

Further, the quantum well layer 6 is a multiple quantum well layer 6, the lower waveguide layer 5 may also be referred to as a lower waveguide layer 5, and the upper waveguide layer 7 may also be referred to as an upper waveguide layer 7.

Further, the quantum well is a structure that provides gain.

The active section further comprises a first confinement layer 8 and an etch stop layer 9 which are stacked; the first section of the first confinement layer 8 and the first section of the etch stop layer 9 are located within the active section, the upper waveguide layer 7 is disposed on the first section of the first confinement layer 8, and the active section ridge waveguide 10 is disposed on the first section of the etch stop layer 9; the second section of the first limiting layer 8 and the second section of the corrosion stop layer 9 are positioned in the passive section, the first waveguide 14, the second waveguide 15 and the expansion waveguide 16 are arranged on the corrosion stop layer 9, and the arrangement positions are provided for the active section ridge waveguide 10 and the passive section ridge waveguide structure through the arrangement of the first limiting layer 8 and the corrosion stop layer 9. The first limiting layer 8 can be prevented from being damaged when the etching stop layer 9 is far away from the first limiting layer 8 and wet etching is carried out through the arrangement of the etching stop layer 9, and the optical field can be well regulated and controlled through the arrangement of the first limiting layer 8.

Further, the first confinement layer 8 and the etch stop layer 9 are disposed in the horizontal direction.

Further, the first confinement layer 8 is a P-type confinement layer.

The active section further comprises an ohmic contact layer 11 and an electrode 12 which are overlapped, the ohmic contact layer 11 is connected with the active section ridge waveguide 10, the electrode 12 is located on one side, away from the active section ridge waveguide 10, of the ohmic contact layer 11, and through the arrangement of the electrode 12, current can be injected into the active section, light gain is generated, and lasing is achieved. By providing the ohmic contact layer 11, an ohmic contact eliminating potential difference can be formed when the metal electrode is in contact with the semiconductor material.

Further, the ohmic contact layer 11 and the electrode 12 are disposed in a horizontal direction.

Further, the electrode 12 is a P-type electrode.

The active section further comprises a grating layer 3 and a second limiting layer 4 which are overlapped, the second limiting layer 4 is connected with the lower waveguide layer 5, the grating layer 3 is located on one side, away from the lower waveguide layer 5, of the second limiting layer 4, the optical field can be well regulated and controlled by arranging the second limiting layer 4, and the first limiting layer 8 and the second limiting layer 4 can limit the diffusion of the P-type or N-type doped vector quantum well region. The grating layer is a selective structure of laser wavelength.

Further, the second confinement layer 4 is an N-type confinement layer.

The active section still includes substrate 1 and the buffer layer 2 of looks superpose, and buffer layer 2 is located between substrate 1 and grating layer 3, and grating layer 3 sets up on buffer layer 2, through setting up buffer layer 2, can prevent that substrate 1 and grating layer 3 and upper structure lattice mismatch from leading to unable direct growth.

Further, a portion of the substrate 1 and a portion of the buffer layer 2 are located in the passive section, and another portion is located in the active section.

Further, the substrate 1, the buffer layer 2, the grating layer 3, the second confinement layer 4, the lower waveguide layer 5, the quantum well layer 6, the upper waveguide layer 7, the first confinement layer 8, the etch stop layer 9, the active section ridge waveguide 10, the ohmic contact layer 11, and the electrode 12 are sequentially stacked in a vertical direction.

The first section of the second confinement layer 4 is located in the active section, the second section of the second confinement layer 4 is located in the passive section, and the passive waveguide layer 13 is sandwiched between the second section of the second confinement layer 4 and the second section of the first confinement layer 8.

The grating layer 3, the ohmic contact layer 11, and the electrode 12 extend in a first direction; the grating layer 3, the ohmic contact layer 11, the electrode 12, the lower waveguide layer 5, the quantum well layer 6, the upper waveguide layer 7, and the active section ridge waveguide 10 have the same length along the first direction, that is, the lengths of the active sections in the first direction are the same at all positions.

Further, the substrate 1, the buffer layer 2, the grating layer 3, the second limiting layer 4, the lower waveguide layer 5, the quantum well layer 6, the upper waveguide layer 7, the first limiting layer 8, the corrosion stop layer 9, the active section ridge waveguide 10, the ohmic contact layer 11, and the electrode 12 form a dielectric layer, and the active section ridge waveguide 10 and the passive section ridge waveguide are located in the same layer of the dielectric layer.

Furthermore, when the laser works, only the current needs to be injected into the active section, so that the gain is provided. The passive section acts to expand the mode field and does not provide gain.

The fabrication material of the passive waveguide layer 13 includes InGaAsP; the quantum well layer 6 is made of a material including InGaAlAs or InGaAsP; the bandgap of the passive waveguide layer 13 is greater than the bandgap of the quantum well layer 6. The band gap of the passive waveguide layer is larger than that of the quantum well layer 6, so that the passive section waveguide layer can be prevented from absorbing the light amplified by the active region, and the intracavity light loss is caused.

The thicknesses and refractive indexes of the buffer layer 2, the grating layer 3, the second limiting layer 4, the lower waveguide layer 5, the quantum well layer 6, the upper waveguide layer 7, the first limiting layer 8, the passive waveguide layer 13, the corrosion stop layer 9 and the active section ridge waveguide 10 are shown in the following table:

TABLE 1 thickness and refractive index of each dielectric layer

Dielectric layer	Thickness nm	Refractive index
			Buffer layer	——	3.2
Grating layer	45	3.24
			A second confinement layer	35	3.2
First waveguide layer	30	3.45
			Quantum well layer	90	3.48
Second waveguide layer	30	3.45
			A first confinement layer	35	3.2
Passive waveguide layer	200	3.48
			Etch stop layer	100	3.2
Active segment ridge waveguide	2000	3.2

In another aspect of the present embodiment, a method for manufacturing a laser is provided, which is used for manufacturing the laser as described above.

The manufacturing method comprises the following steps:

sequentially epitaxially growing a buffer layer 2, a grating layer 3, a second limiting layer 4, a lower waveguide layer 5, a quantum well layer 6 and an upper waveguide layer 7 on the top surface of the substrate 1 along the normal direction of the top surface;

manufacturing a silicon dioxide mask, and covering the silicon dioxide mask on the upper waveguide layer 7 in the active section;

etching and removing the grating layer 3, the second limiting layer 4, the lower waveguide layer 5, the quantum well layer 6 and the upper waveguide layer 7 in the passive section;

epitaxially growing a passive waveguide layer 13 on the lower waveguide layer 5 in the passive section;

removing the silicon dioxide mask and epitaxially growing a first confinement layer 8 and an etch stop layer 9, an upper cladding layer and an ohmic contact layer 11 on the upper waveguide layer 7 and the passive waveguide layer 13;

a photoresist mask is manufactured through photoetching, the ohmic contact layer in the active section is covered, and the ohmic contact layer in the passive section is corroded by a wet method;

and manufacturing an SiN mask through photoetching, and etching an upper cladding ridge waveguide 10, a tapered graded waveguide 14, a narrow waveguide 15 and a mode expansion waveguide 16 at the output end of the laser through dry etching and wet etching to finish the manufacture of the laser.

Further, the upper waveguide layer 7 in the active section can be prevented from being etched and removed by using the silicon dioxide mask, only the grating layer 3, the second limiting layer 4, the lower waveguide layer 5, the quantum well layer 6 and the upper waveguide layer 7 in the passive section are etched and removed, a step structure is formed, a setting position is provided for the passive waveguide layer 13, and the passive waveguide layer 13 and the quantum well layer 6 can be oppositely arranged.

Further, the first waveguide 14, the second waveguide 15, and the extension waveguide 16 are formed on the etch stop layer 9 in the passive section, and the active section ridge waveguide 10 is formed on the etch stop layer 9 in the active section.

Further, the ohmic contact layer 11 in the active segment is prevented from being etched away by using a photoresist mask.

Furthermore, a silicon dioxide mask and a photoresist mask are manufactured through photoetching, so that the silicon dioxide mask and the photoresist mask are guaranteed to have good isolation effect.

Further, the grating layer 3, the second limiting layer 4, the lower waveguide layer 5, the quantum well layer 6 and the upper waveguide layer 7 in the passive section are removed through dry etching and wet etching, the etching depth is 1000-2000 nm, a step structure with a stable structure and an accurate position is formed, and a setting position is provided for the passive waveguide layer 13.

Further, the passive waveguide layer 13 is epitaxially grown on the lower waveguide layer 5 in the passive section by a vapor phase epitaxy growth technology MOCVD, so that the stability of the passive waveguide layer 13 is ensured.

Further, the ohmic contact layer 11 in the passive section is removed by wet etching, so that a good removal effect is ensured.

The passive segment ridge waveguide structure and the laser provided by the embodiment of the invention can reduce the divergence angle of output light beams and realize high-efficiency light field coupling. The embodiment of the invention provides a method for manufacturing a passive segment ridge waveguide structure, which can manufacture the passive segment ridge waveguide structure capable of reducing the divergence angle of output light beams and realizing high-efficiency optical field coupling.

It is readily understood by a person skilled in the art that the advantageous ways described above can be freely combined, superimposed without conflict.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present application, and these modifications and variations should also be considered as the protection scope of the present application.

Claims

1. A passive segment ridge waveguide structure comprising a first waveguide (14), a second waveguide (15) and at least one expansion waveguide (16); the first waveguide (14) comprises a light inlet end and a light outlet end, and the second waveguide (15) is positioned on one side of the first waveguide (14) close to the light outlet end, so that part of light beams entering from the light inlet end sequentially pass through the light outlet end and the second waveguide (15) to be transmitted out of the passive section ridge waveguide structure; at least one expansion waveguide (16) is arranged on the outer periphery side of the second waveguide (15), and the cross section of the first waveguide (14) is reduced along the direction towards the second waveguide (15) so that part of the light beam entering from the light inlet end propagates to the outside of the passive section ridge waveguide structure through the second waveguide (15).

2. The passive segment ridge waveguide structure of claim 1, wherein the second waveguide (15) meets the light exit end and the contact surfaces coincide, and the first waveguide (14) and the second waveguide (15) extend in the same direction.

3. The passive segment ridge waveguide structure according to claim 1, wherein the number of the extension waveguides (16) is two, two of the extension waveguides (16) are arranged in parallel, and two of the extension waveguides (16) are symmetrically arranged on the outer peripheral side of the second waveguide (15) with respect to the second waveguide (15).

4. The passive segment ridge waveguide structure of claim 1, wherein the extension waveguide (16) is disposed parallel to the second waveguide (15).

5. The passive segment ridge waveguide structure of claim 1, wherein the first waveguide (14) is a hexahedron, the outer walls between the light input end and the light output end are a first outer wall, a second outer wall, a third outer wall and a fourth outer wall, the first outer wall and the second outer wall are arranged oppositely, the first outer wall and the second outer wall are converged toward the center of the first waveguide (14) along the direction toward the second waveguide (15) so as to enable part of the light beam entering from the light input end to propagate into the second waveguide (15), and the third outer wall and the fourth outer wall are arranged oppositely and in parallel.

6. The passive segment ridge waveguide structure of claim 5, wherein the first outer wall, the second outer wall, the third outer wall and the fourth outer wall are all planar, the first waveguide (14) and the second waveguide (15) extend along a first direction, and the length of the whole formed by the first waveguide (14) and the second waveguide (15) along the first direction is 15-60 μm.

7. The passive segment ridge waveguide structure of claim 6, wherein the first waveguide (14) has a length along the first direction of 5-20 μm, the second waveguide (15) has a length along the first direction of 10-40 μm, the extension waveguide (16) extends along the first direction, and the extension waveguide (16) has a length along the first direction of 10-40 μm.

8. The passive segment ridge waveguide structure of claim 7, wherein the first waveguide (14), the second waveguide (15) and the extension waveguide (16) are located in a first plane, the length of the projection of the light inlet end in the first plane is 1.5-2.5 μm, the length of the projection of the light outlet end in the first plane is 0.5-1.2 μm, the projection of the second waveguide (15) and the extension waveguide (16) in the first plane is a rectangle, and the width of the rectangle is 0.5-1.2 μm.

9. The passive segment ridge waveguide structure of claim 1, characterized in that the extension waveguide (16) is arranged apart from the second waveguide (15), and a gap of 0.5-2 μm is arranged between the extension waveguide (16) and the second waveguide (15).

10. A method of fabricating a passive segment ridge waveguide structure, comprising:

manufacturing a mask;

covering the mask on a substrate;

and etching a first waveguide (14), a second waveguide (15) and at least one extension waveguide (16) on the base material by dry etching and wet etching, etching the second waveguide (15) at one side of the light outlet end of the first waveguide (14), etching the first waveguide to have a gradually decreasing cross section along the direction towards the second waveguide (15), and etching at least one extension waveguide (16) at the outer periphery side of the second waveguide (15).

11. A laser comprising a passive section ridge waveguide structure according to any of claims 1-9, the laser comprising a passive section and an active section, the passive section being contiguous with the active section, the passive section ridge waveguide structure being part of the passive section.

12. The laser of claim 11, wherein the active section comprises an active section ridge waveguide (10), the active section ridge waveguide (10) interfacing with the light entrance end of the first waveguide (14), the active section ridge waveguide and the first waveguide (14) extending in a first direction.

13. The laser device according to claim 11, further comprising an antireflection film (17) and a reflection film (18), wherein the antireflection film (17) is covered on one end of the passive section far away from the active section, and the reflection film (18) is covered on one end of the active section far away from the passive section.