CN114825031B - Semiconductor laser and preparation method thereof - Google Patents
Semiconductor laser and preparation method thereof Download PDFInfo
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- CN114825031B CN114825031B CN202210720757.2A CN202210720757A CN114825031B CN 114825031 B CN114825031 B CN 114825031B CN 202210720757 A CN202210720757 A CN 202210720757A CN 114825031 B CN114825031 B CN 114825031B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/024—Arrangements for thermal management
- H01S5/02461—Structure or details of the laser chip to manipulate the heat flow, e.g. passive layers in the chip with a low heat conductivity
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
- H01S5/2202—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure by making a groove in the upper laser structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/24—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a grooved structure, e.g. V-grooved, crescent active layer in groove, VSIS laser
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Abstract
The invention relates to the technical field of semiconductors, and provides a semiconductor laser and a preparation method thereof, wherein an isolation groove is arranged on an epitaxial layer at a position corresponding to an extension waveguide structure, so that the isolation groove extends to a ridge waveguide structure below; the isolation grooves are arranged between the adjacent ridge waveguide structures, so that the expansion effect of reducing current to the cavity surface is achieved, the heating and accelerated degradation caused by the absorption of the carrier on the cavity surface are reduced, and the COMD reliability is improved; meanwhile, the laser structure increases high-order mode loss through the expansion waveguide structure, so that a fundamental mode is more stable, and the single-mode output stability of the laser is improved.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a semiconductor laser and a preparation method thereof.
Background
The semiconductor high-power laser has wide application in the fields of industrial manufacturing, laser radar, sensing, communication, aerospace and the like. Because of the advantage of easy extension of the cavity length of the edge-emitting laser, the edge-emitting laser is more suitable for manufacturing high-power lasers, and the existing semiconductor high-power lasers generally adopt an edge-emitting structure, namely, the light-emitting surface is the end surface of the waveguide and is parallel to the direction of the epitaxial layer.
The cavity surface of the edge-emitting laser is generally a cleavage surface of a semiconductor crystal, and because the cleavage surface of the crystal is very flat and smooth and is a good light-reflecting surface, two parallel cleavage end surfaces of a chip naturally form the cavity surface of the resonant cavity of the edge-emitting laser. However, with the further increase of the laser power, despite the protection of the facet coating, the cavity facet burn-out (COMD) of the laser is still a difficult problem, which limits the reliability of the semiconductor high-power laser and also limits the further increase of the laser power.
Disclosure of Invention
The invention aims to provide a semiconductor laser and a preparation method thereof, which aim to solve the problem that the cavity surface of the existing semiconductor laser is burnt.
In a first aspect, an embodiment of the present invention provides a semiconductor laser, including: the epitaxial layer is formed on the substrate; the epitaxial layer comprises a first semiconductor cladding layer, a first semiconductor waveguide layer, a quantum well layer, a second semiconductor waveguide layer, a second semiconductor cladding layer and an ohmic contact layer which are sequentially stacked; the second semiconductor cladding layer or the stacked second semiconductor cladding layer and second semiconductor waveguide layer comprises a plurality of ridge waveguide structures which extend along the first direction and are arranged discontinuously, and extension waveguide structures which connect the adjacent ridge waveguide structures, wherein the size of the extension waveguide structures along the second direction is larger than that of the ridge waveguide structures along the second direction; wherein the first direction is a cavity length direction of the semiconductor laser, and the second direction is a cavity width direction of the semiconductor laser; the epitaxial layer comprises at least one isolation groove, the orthographic projection of the isolation groove on the substrate is overlapped with the orthographic projection of the extended waveguide structure on the substrate, and the isolation groove cuts off the ohmic contact layer and extends to the second semiconductor cladding layer or the second semiconductor waveguide layer;
the conductive function layer is positioned on one side, far away from the substrate, of the ohmic contact layer and covers the isolation groove.
Optionally, a dimension of the isolation trench in the second direction is greater than a dimension of the ridge waveguide structure in the second direction and is less than or equal to a dimension of the extension waveguide structure in the second direction.
Optionally, a dimension of the isolation trench along the first direction is greater than 5 microns and less than 20% of a cavity length of the semiconductor laser; the cavity length is the distance between the light emitting cavity surface and the reflecting cavity surface of the semiconductor laser.
Optionally, the epitaxial layer further includes two ridge waveguide trenches, and both of the ridge waveguide trenches extend along the first direction and are symmetrically disposed on both sides of the ridge waveguide structure; the bottom of the ridge waveguide groove extends into the second semiconductor cladding layer or the second semiconductor waveguide layer; the ridge waveguide groove penetrates through the first direction or is separated by the extension waveguide structure, and the plane where the groove bottom of the isolation groove is located is higher than the plane where the groove bottom of the ridge waveguide groove is located.
Optionally, the ridge waveguide trench extends to an edge of the semiconductor laser along the second direction; and side waveguide structures are arranged at the bottoms of the ridge waveguide grooves and distributed on two sides of the expansion waveguide structure along the second direction.
Optionally, the distance between the side waveguide structure and the expansion waveguide structure on the corresponding side is 0-10 micrometers.
Optionally, when the size of the isolation slot in the second direction is smaller than the size of the expansion waveguide in the second direction, the isolation slot includes two first slot walls that are oppositely disposed in the second direction, and the two first slot walls are an inclined surface structure that gradually expands upward from the slot bottom of the isolation slot.
Optionally, the isolation groove includes two second groove walls oppositely arranged along the first direction, and the two second groove walls are symmetrically arranged and are both in a stepped structure; the width between different steps of the two second groove walls is increased in sequence from the upward direction of the groove bottom of the isolation groove.
Optionally, the number of the extended waveguide structures is one, and the extended waveguide structures are disposed close to the reflecting cavity surface; the expansion waveguide structure separates two ridge waveguide structures arranged at intervals.
Optionally, the number of the extended waveguide structures is two, one of the extended waveguide structures is disposed near the light exit cavity surface, and the other of the extended waveguide structures is disposed near the reflection cavity surface; the two expansion waveguide structures are separated into three ridge waveguide structures which are arranged at intervals.
In a second aspect, an embodiment of the present invention provides a method for manufacturing a semiconductor laser, which is used to manufacture the semiconductor laser according to the first aspect, and includes:
providing a substrate;
preparing an epitaxial layer on one side of the substrate;
patterning the epitaxial layer to form a ridge waveguide structure and an extension waveguide structure;
forming the isolation groove in the region where the expansion waveguide structure is located;
and forming a conductive function layer covering the isolation groove on the epitaxial layer.
The embodiment of the invention at least has the following technical effects:
according to the semiconductor laser provided by the embodiment of the invention, the isolation groove is arranged at the position of the epitaxial layer corresponding to the extension waveguide structure, so that the isolation groove extends to the ridge waveguide structure below, the isolation groove is not directly processed on the ridge waveguide structure but processed on the extension waveguide connected with the ridge waveguide structure, and the width of the extension waveguide structure is greater than that of the ridge waveguide structure, so that the processing difficulty of the isolation groove is reduced; the isolation grooves are arranged between the adjacent ridge waveguide structures, so that the expansion effect of reducing current to the cavity surface is achieved, the heating and accelerated degradation caused by the absorption of the carrier on the cavity surface are reduced, and the COMD reliability is improved; the laser structure increases high-order mode loss, so that a fundamental mode is more stable, and the power of the laser is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic cross-sectional view of a semiconductor laser along a second direction according to an embodiment of the present invention;
fig. 2 is a schematic projection diagram of an epitaxial layer of a semiconductor laser device provided by an embodiment of the present invention on a substrate;
fig. 3 is a schematic projection diagram of an epitaxial layer of another semiconductor laser device provided by an embodiment of the present invention on a substrate;
fig. 4 is a schematic projection diagram of an epitaxial layer of another semiconductor laser device provided by an embodiment of the present invention on a substrate;
fig. 5 is a schematic projection diagram of an epitaxial layer of another semiconductor laser device provided by an embodiment of the present invention on a substrate;
fig. 6 is a schematic projection diagram of an epitaxial layer of a semiconductor laser device on a substrate according to another embodiment of the present invention;
fig. 7 is a schematic cross-sectional view of an isolation trench of a semiconductor laser according to an embodiment of the present invention along a first direction;
fig. 8 is a schematic diagram illustrating a distribution relationship between a ridge waveguide structure and an isolation trench of a semiconductor laser according to an embodiment of the present invention;
fig. 9 is a schematic diagram illustrating a distribution relationship between a ridge waveguide structure and an isolation trench of another semiconductor laser according to an embodiment of the present invention;
fig. 10 is a schematic diagram illustrating a distribution relationship between a ridge waveguide structure and an isolation trench of another semiconductor laser according to an embodiment of the present invention;
fig. 11 is a schematic diagram illustrating a distribution relationship between a ridge waveguide structure and an isolation trench of another semiconductor laser according to an embodiment of the present invention;
fig. 12 is a schematic structural diagram of a method for fabricating a semiconductor laser according to an embodiment of the present invention;
fig. 13 is a schematic structural diagram corresponding to step S100 in the method for manufacturing a semiconductor laser according to the embodiment of the present invention.
Icon: 100-a substrate; 101-a reflective facet; 102-a light exit facet;
200-an epitaxial layer; 200 a-an expanded waveguide region; 200 b-waveguide region; 200 c-an isolation trench; 201-a second slot wall; 210 — a first semiconductor cladding; 220 — first semiconductor waveguide layer; 230-a quantum well layer; 240-a second semiconductor waveguide layer; 250-a second semiconductor cladding layer; 250 a-a ridge waveguide structure; 250 b-ridge waveguide trenches; 250 c-an extended waveguide structure; a 250 d-side waveguide structure; 260-ohmic contact layer;
300-a conductive functional layer; 310-a dielectric layer; 320-metal layer.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.
As shown in fig. 1 and 2, an embodiment of the present invention provides a semiconductor laser including: a substrate 100, and an epitaxial layer 200 and a conductive functional layer 300 which are sequentially stacked on the substrate 100.
Specifically, epitaxial layer 200 includes at least one expansion waveguide region 200a and a plurality of waveguide regions 200b separated by expansion waveguide region 200 a. For convenience of description, in the present embodiment, a region of the epitaxial layer 200 corresponding to the extension waveguide structure 250c is defined as an extension waveguide region 200a, a region of the epitaxial layer 200 corresponding to the ridge waveguide structure 250a is positioned as a waveguide region 200b, and adjacent waveguide regions 200b are separated by the extension waveguide region 200a, so that the plurality of waveguide regions 200b are intermittently distributed along the first direction. The first direction is a cavity length direction of the semiconductor laser, i.e., a direction parallel to the light exit cavity surface 102 (AR cavity surface) and pointing to the reflection cavity surface 101 (HR cavity surface).
The epitaxial layer 200 in this embodiment is formed on the substrate 100, and the epitaxial layer 200 is mainly used for confinement and transmission of an optical mode, and specifically includes a first semiconductor cladding layer 210, a first semiconductor waveguide layer 220, a quantum well layer 230, a second semiconductor waveguide layer 240, a second semiconductor cladding layer 250, and an ohmic contact layer 260, which are sequentially stacked on the substrate 100.
Optionally, the first semiconductor cladding layer 210 is an N-type cladding layer, and the first semiconductor waveguide layer 220 is an N-type waveguide layer; the second semiconductor waveguide layer 240 is a P-type waveguide layer and the second semiconductor cladding layer 250 is a P-type cladding layer.
Further, the second semiconductor cladding layer 250 includes a plurality of ridge waveguide structures 250a extending along the first direction and arranged intermittently, and an extension waveguide structure 250c connecting adjacent ridge waveguide structures 250a, and the second semiconductor waveguide layer 240 is a complete film structure; alternatively, the stacked second semiconductor waveguide layer 250 and the second semiconductor waveguide layer 240 include a plurality of ridge waveguide structures 250a extending along the first direction and disposed discontinuously, and an extension waveguide structure 250c connecting adjacent ridge waveguide structures 250a, i.e., the ridge waveguide structure 250a includes at least a portion of the stacked second semiconductor waveguide layer 240 and the second semiconductor waveguide layer 250. The dimension of the extension waveguide structure 250c in the second direction (i.e., the width of the extension waveguide structure 250 c) is greater than the dimension of the ridge waveguide structure 250a in the second direction (i.e., the width of the ridge waveguide structure 250 a); wherein the second direction is a cavity width direction of the semiconductor laser (i.e., a direction parallel to the AR cavity surface or the HR cavity surface).
The epitaxial layer 200 includes at least one isolation trench 200c, an orthographic projection of the isolation trench 200c on the substrate overlaps with an orthographic projection of the extended waveguide structure 250c on the substrate, that is, the isolation trench 200c is specifically disposed in an extended waveguide region where the extended waveguide structure 250c is located, and the isolation trench 200c separates the ohmic contact layer and extends to the second semiconductor cladding 250; alternatively, when the ridge waveguide structure 250a and the extension waveguide structure 250c belong to the second semiconductor cladding layer 250 and the second semiconductor waveguide layer 240 which are arranged in a stack, the isolation trench 200c may extend to the second semiconductor cladding layer 250 and also to the second semiconductor waveguide layer 240.
Further, the conductive function layer 300 is located on a side of the ohmic contact layer 260 away from the substrate 100, the conductive function layer 300 covers the isolation groove 200c, and the conductive function layer 300 facilitates electrical connection of the ohmic contact layer 260 with an external voltage applying device.
Optionally, the conductive function layer 300 includes a dielectric layer 310 and a metal layer 320, which are sequentially disposed, and the dielectric layer 310 covers the ohmic contact layer 260. The dielectric layer 310 is mainly used for electrical isolation, and a partial region of the dielectric layer is etched to selectively perform electrical injection.
The epitaxial layer 200 in this embodiment includes at least one isolation trench 200c, and the isolation trench 200c is located in the extended waveguide region 200a, so that each isolation trench 200c is correspondingly located in the extended waveguide region 200 a. Meanwhile, since the position of the isolation trench 200c is removed from the ohmic contact layer 260, that is, the trench bottom of the isolation trench 200c extends downward to the upper surface of the extended waveguide structure 250c (the upper surface of the extended waveguide structure 250c corresponds to the surface of the second semiconductor cladding layer 250 on the side of the extended waveguide region 200a and away from the substrate 100), such an isolation trench 200c serves as an electrical isolation between the adjacent waveguide regions 200 b.
It should be noted that, besides the isolation groove 200c isolating the conductive functional layer 300, a plane of a groove bottom of the isolation groove 200c may be lower than a plane of an upper surface of the extended waveguide structure 250c (that is, the groove bottom of the isolation groove extends to the inside of the extended waveguide structure 250 c), so that the isolation effect may be further improved. The extension waveguide structure 250c may include a single layer of the second semiconductor cladding layer 250, or may be a stacked structure of the second semiconductor cladding layer 250 and the second semiconductor waveguide layer 240.
In the semiconductor laser provided by the embodiment, the isolation groove is arranged at the position of the epitaxial layer corresponding to the extension waveguide structure, so that the isolation groove extends to the ridge waveguide structure below, because the isolation groove is not directly processed on the ridge waveguide structure but processed on the extension waveguide connected with the ridge waveguide structure, and the width of the extension waveguide structure is greater than that of the ridge waveguide structure, the processing difficulty of the isolation groove is reduced; the isolation grooves are arranged between the adjacent ridge waveguide structures, so that the expansion effect of reducing current to the cavity surface is achieved, the heating and accelerated degradation caused by the absorption of the carrier on the cavity surface are reduced, and the COMD reliability is improved; meanwhile, the laser structure increases high-order mode loss through the expansion waveguide structure, so that a fundamental mode is more stable, and the power of the laser is improved.
In some embodiments, with continued reference to fig. 2, the dimension of the isolation trench 200c in the second direction is greater than the dimension of the ridge waveguide structure 250a in the second direction (corresponding to the width of the ridge waveguide structure 250 a), which facilitates the implementation of the etching process.
Further, the size of the isolation trench 200c in the second direction is smaller than or equal to the size of the extension waveguide structure 250c in the second direction, that is, the size of the isolation trench 200c in the second direction does not exceed the size of the extension waveguide structure 250c in the second direction, so that the influence of secondary etching on the region outside the extension waveguide structure 250c on the stability of the fundamental mode can be avoided.
In this embodiment, since the isolation trench 200c is formed in the extension waveguide region 200a and is not limited by the width of the ridge waveguide structure 250a of the waveguide region 200b, the width of the isolation trench 200c can be made larger than that of the ridge waveguide structure 250a, which reduces the difficulty in the etching process, and can further reduce the local current density in the end region of the laser, thereby improving the performance of the laser and limiting the isolation trench 200c in the region where the extension waveguide structure 250c is located.
In some embodiments, with continuing reference to fig. 2, the present embodiment controls the dimension of the isolation trench 200c along the first direction within a certain range by considering the transmission efficiency of light and the electrical isolation effect.
Optionally, the dimension of the isolation trench 200c in the first direction is greater than 5 microns and less than 20% of the cavity length of the semiconductor laser. The cavity length is the distance between the light-emitting cavity surface and the reflecting cavity surface along the first direction.
Alternatively, the size of the isolation trench 200c in the first direction is generally 20 to 100 micrometers.
In this embodiment, the size of the isolation groove 200c along the first direction is limited within a certain range, so that transmission efficiency and electrical isolation effect can be considered, the size of the isolation groove 200c along the first direction is too small to affect the electrical isolation effect, and the size of the isolation groove 200c along the first direction is too large to increase loss to affect the optical transmission efficiency.
In some embodiments, with continued reference to fig. 1 and 2, epitaxial layer 200 further comprises: two ridge waveguide grooves 250b, the two ridge waveguide grooves 250b each extend in the first direction and are symmetrically disposed on both sides of the ridge waveguide structure 250 a. The ridge waveguide trench 250b may be prepared on the second semiconductor cladding layer 250 by an etching process, thereby forming a ridge waveguide structure 250a sandwiched between the ridge waveguide trenches 250 b.
Specifically, the groove bottom of the ridge waveguide groove 250b extends into the second semiconductor cladding layer 250 or into the second semiconductor waveguide layer 240, which corresponds to removing a portion of the second semiconductor cladding layer 250 or removing a portion of both the second semiconductor cladding layer 250 and the second semiconductor waveguide layer 240.
Further, the ridge waveguide groove 250b is through or separated by the extended waveguide structure 250c along the first direction, and the plane where the groove bottom of the isolation groove is located is higher than the plane where the groove bottom of the ridge waveguide groove is located, so that the influence on the fundamental mode is avoided.
Further, the size of the isolation groove 200c in the second direction is smaller than the sum of the sizes of the ridge waveguide and the two ridge waveguide trenches 250b in the second direction.
In an alternative embodiment, the ridge waveguide trench 250b has the same dimension along the first direction as the ridge waveguide structure 250a at the corresponding position, i.e., the ridge waveguide trench 250b does not overlap the extension waveguide region 200 a.
In an alternative embodiment, the ridge waveguide trench 250b extends to the edge of the semiconductor laser in the second direction, as shown in fig. 3.
Alternatively, as shown in fig. 4, when the ridge waveguide trench 250b is formed, the side waveguide structure 250d may be left unetched, and the side waveguide structure 250d protrudes from the bottom of the ridge waveguide trench 250 b. The side waveguide structures are distributed on two sides of the extended waveguide structure 250c along the second direction, and a preset distance is reserved between the side waveguide structures and the extended waveguide structure, so that high-order mode divergence is further increased, high-order mode loss is reduced, a basic mode is not affected, and the basic mode is more stable.
Optionally, the distance between the side waveguide structure and the corresponding side extension waveguide structure 250c is 0-10 micrometers, and a too large distance may affect high-order mode loss. It should be noted that, when the distance between the side waveguide structure and the corresponding side extension waveguide structure 250c is 0, the side waveguide structure and the extension waveguide structure 250c are integrated, which is equivalent to increasing the size of the extension waveguide structure 250c along the second direction.
In an alternative embodiment, with continued reference to fig. 2, when the dimension of the isolation trench 200c in the second direction is smaller than the dimension of the extended waveguide structure 250c in the second direction, the isolation trench includes two first trench walls (not shown in the figure) oppositely disposed in the second direction, and the two first trench walls are slope structures gradually expanding upwards from the trench bottom of the isolation trench, so as to reduce the disturbance to the optical field and the loss to the optical mode on the basis of ensuring good electrical isolation.
In an alternative embodiment, as shown in fig. 5, when the dimension of the isolation trench 200c in the second direction is equal to the dimension of the extended waveguide structure 250c in the second direction, the isolation trench 200c is communicated with the ridge waveguide trench 250b, and the plane of the bottom of the isolation trench 200c is generally higher than the plane of the bottom of the ridge waveguide trench 250b, so as to avoid affecting the fundamental mode.
In an alternative embodiment, as shown in fig. 6, when the dimension of the isolation trench 200c in the second direction is larger than the dimension of the extension waveguide structure 250c in the second direction, the isolation trench 200c penetrates the ridge waveguide trench 250b and extends to a partial region of the ridge waveguide trench 250b, and the isolation trench 200c extending to a region where the ridge waveguide trench 250b is located further etches the ridge waveguide trench 250 b.
It should be noted that, the plane where the isolation trench 200c is located at the bottom of the extended waveguide region 200a is generally higher than the plane where the bottom of the ridge waveguide trench 250b is located, so as to avoid affecting the fundamental mode, and meanwhile, the isolation trench 200c partially extends to the region where the ridge waveguide trench 250b is located, so as to further improve the COMD.
In an alternative embodiment, referring to fig. 7, the isolation trench 200c includes two second trench walls 201 disposed opposite to each other along the first direction, and the two second trench walls 201 are symmetrically disposed and both have a stepped structure, wherein one second trench wall 201 is close to the ridge waveguide structure 250a at the end of the reflecting cavity surface 101, and the other second trench wall 201 is close to the ridge waveguide structure 250a of the light exit cavity surface 102.
Specifically, each second groove wall 201 is similar to a staircase in structure, such that the width between different steps of the two second groove walls 201 increases in sequence from the upward direction of the groove bottom of the isolation groove 200c, i.e., the distance between the positions of the two second groove walls 201 at the groove bottom is the smallest.
In this embodiment, the second groove wall 201 of the isolation groove 200c is configured to be a stepped structure, so that the loss of the fundamental mode light can be reduced, and the light emitting efficiency can be improved.
In an alternative embodiment, with continued reference to fig. 2 and 8, the number of extended waveguide regions 200a in this embodiment is one, the extended waveguide region 200a is disposed adjacent to the reflective facet 101 (HR facet) and between two waveguide regions 200b, one of the waveguide regions 200b is adjacent to the AR facet, the other waveguide region 200b is adjacent to the HR facet, and the area of the waveguide region 200b adjacent to the HR facet is smaller.
Specifically, since the extension waveguide region 200a is provided with one extension waveguide structure 250c, it is equivalent to providing only one extension waveguide structure 250 c. The extended waveguide structure 250c is disposed near the reflecting facet 101 (HR facet) and separates two ridge waveguide structures 250a, and the extended waveguide structure 250c connects the ridge waveguide structures 250a on both sides into an integral structure.
Alternatively, as shown in fig. 9 and 10, the number of the extended waveguide region 200a and the corresponding extended waveguide structure 250c in the present embodiment is one, and the extended waveguide region 200a is disposed near the reflective cavity surface 101 (HR cavity surface). The portion of the extended waveguide structure 250c extending out of the ridge waveguide structure 250a shown in fig. 9 is a trapezoidal structure, and the portion of the extended waveguide structure 250c extending out of the ridge waveguide structure 250a shown in fig. 10 is a semicircular structure, both of which contribute to the stabilization of the fundamental mode.
Further, on the basis of fig. 10, the junction between the extension waveguide structure 250c and the ridge waveguide structure 250a may be connected in a smooth transition manner, which is more favorable for improving the stability of the fundamental mode.
In another alternative embodiment, as shown in fig. 11, there are two extended waveguide regions 200a in the present embodiment, and two extended waveguide regions 200a separate three extended waveguide regions 200b along the first direction, wherein one extended waveguide region 200a is close to the AR cavity surface and the other extended waveguide region 200a is close to the HR cavity surface.
Specifically, since one extension waveguide structure 250c is provided for each waveguide region 200a, it is equivalent to providing two extension waveguide structures 250 c. The two extension waveguide structures 250c separate the three ridge waveguide structures 250a, and each extension waveguide structure 250c connects the ridge waveguide structures 250a on adjacent sides. Since the two isolation grooves 200c are respectively disposed between the adjacent ridge waveguide structures 250a, the adjacent ridge waveguide structures 250a are isolated, and the dimension of the two isolation grooves 200c in the second direction exceeds the width of the extension waveguide structure 250c in the second direction, which is beneficial to further improving the COMD.
Optionally, when there are three waveguide regions 200a and three corresponding ridge waveguide structures 250a, the width of the ridge waveguide structure disposed near the light exit cavity surface is equal to the width of the ridge waveguide structure disposed near the reflection cavity surface, so that optical mode loss can be avoided, and the transmission effect of laser light can be ensured.
Alternatively, the widths of the two ends of the ridge waveguide structure in the middle waveguide region may be set to be the same or different (for example, the widths of the two ends are gradually changed or designed to be equal), as long as the widths of the ridge waveguide structures close to the AR cavity surface and the HR cavity surface are ensured to be equal.
In the embodiment, a waveguide structure design of gradual change and/or multiple sections is adopted to design the waveguide from the ridge waveguide structure to the cavity surface, so that more stable and higher coupling efficiency is realized, and good electrical isolation between the waveguide region and the expansion waveguide region is ensured.
Based on the same inventive concept, as shown in fig. 12, an embodiment of the present invention provides a method for manufacturing a semiconductor laser, which is used for manufacturing the semiconductor laser in the foregoing embodiment, and includes the following steps:
s100, providing a substrate.
S200, preparing an epitaxial layer on one side of the substrate.
Specifically, the epitaxial layer covers the surface of the entire substrate, the epitaxial layer specifically includes a first semiconductor cladding layer, a first semiconductor waveguide layer, a quantum well layer, a second semiconductor waveguide layer, a second semiconductor cladding layer, and an ohmic contact layer, which are sequentially stacked on the substrate, positions of an extended waveguide region and a waveguide region of the epitaxial layer are shown in fig. 13, only a relative position relationship between the extended waveguide region and the waveguide region is illustrated in fig. 13, and specific dimensions may be adjusted according to actual laser design requirements.
And S300, patterning the epitaxial layer to form a ridge waveguide structure and an extension waveguide structure.
Specifically, the ridge waveguide structure and the extension waveguide structure may be obtained by etching the second semiconductor cladding layer and the ohmic contact layer, or may be obtained by etching the ohmic contact layer, the second semiconductor cladding layer, and a part of the second semiconductor waveguide layer.
And S400, forming an isolation groove exposing the second semiconductor cladding layer or the second semiconductor waveguide layer in the region where the extended waveguide structure is located.
And S500, forming a conductive function layer covering the isolation groove on the epitaxial layer.
Specifically, the conductive function layer is formed on the ohmic contact layer, electrically connected by contacting with the ohmic contact layer, and covers the opening region of the isolation trench.
In the method for manufacturing the semiconductor laser device provided by this embodiment, the isolation groove is manufactured at the position corresponding to the extension waveguide region through the conductive functional layer 300, and the isolation groove is arranged at the position corresponding to the extension waveguide structure of the epitaxial layer, so that the isolation groove extends to the ridge waveguide structure below; the isolation grooves are arranged between the adjacent ridge waveguide structures, so that the local current density in the end part area of the laser is reduced, the degradation caused and accelerated by local heating of the laser is reduced, and the COMD reliability is improved; meanwhile, the laser structure increases high-order mode loss through the expansion waveguide structure, so that a fundamental mode is more stable, and the power of the laser is improved.
Those skilled in the art will appreciate that the various operations, methods, steps, measures, arrangements of steps in the flow, which have been discussed in the present application, may be alternated, modified, combined, or eliminated. Further, various operations, methods, steps in the flows, which have been discussed in the present application, may be interchanged, modified, rearranged, decomposed, combined, or eliminated. Further, steps, measures, schemes in the various operations, methods, procedures disclosed in the prior art and the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in a specific situation by those skilled in the art.
In the description herein, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and may be performed in other orders unless explicitly stated herein. Moreover, at least a portion of the steps in the flow chart of the figure may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A semiconductor laser, comprising:
a substrate;
an epitaxial layer formed on the substrate; the epitaxial layer comprises a first semiconductor cladding, a first semiconductor waveguide layer, a quantum well layer, a second semiconductor waveguide layer, a second semiconductor cladding and an ohmic contact layer which are sequentially stacked; the second semiconductor cladding layer or the stacked second semiconductor cladding layer and second semiconductor waveguide layer comprises a plurality of ridge waveguide structures which extend along the first direction and are arranged discontinuously, and extension waveguide structures which connect the adjacent ridge waveguide structures, wherein the size of the extension waveguide structures along the second direction is larger than that of the ridge waveguide structures along the second direction; wherein the first direction is a cavity length direction of the semiconductor laser, and the second direction is a cavity width direction of the semiconductor laser;
the epitaxial layer comprises at least one isolation groove, the orthographic projection of the isolation groove on the substrate is overlapped with the orthographic projection of the extension waveguide structure on the substrate, and the isolation groove is used for isolating the ohmic contact layer and extending to the second semiconductor cladding layer or the second semiconductor waveguide layer;
and the conductive functional layer is positioned on one side of the ohmic contact layer, which is far away from the substrate, and covers the isolation groove.
2. The semiconductor laser of claim 1, wherein a dimension of the isolation trench in the second direction is greater than a dimension of the ridge waveguide structure in the second direction; and/or the dimension of the isolation groove along the second direction is smaller than or equal to the dimension of the expansion waveguide structure along the second direction.
3. The semiconductor laser of claim 1, wherein the isolation trench has a dimension along the first direction that is greater than 5 microns and less than 20% of a cavity length of the semiconductor laser; wherein the cavity length is a distance between a light exit cavity surface and a reflective cavity surface of the semiconductor laser.
4. The semiconductor laser of claim 2, wherein the epitaxial layer further comprises two ridge waveguide trenches, both of the ridge waveguide trenches extending in the first direction and symmetrically disposed on both sides of the ridge waveguide structure;
the bottom of the ridge waveguide groove extends into the second semiconductor cladding layer or into the second semiconductor waveguide layer;
the ridge waveguide groove penetrates through or is separated by the extension waveguide structure along the first direction, and the plane where the groove bottom of the isolation groove is located is higher than the plane where the groove bottom of the ridge waveguide groove is located.
5. The semiconductor laser of claim 4, wherein the ridge waveguide trench extends to an edge of the semiconductor laser along the second direction;
and side waveguide structures are arranged at the bottoms of the ridge waveguide grooves and distributed on two sides of the expansion waveguide structure along the second direction.
6. The semiconductor laser of claim 5, wherein the spacing between the side waveguide structure and the extended waveguide structure on the corresponding side is 0-10 microns.
7. The semiconductor laser according to claim 2, wherein when the dimension of the isolation trench in the second direction is smaller than the dimension of the extended waveguide structure in the second direction, the isolation trench includes two first trench walls oppositely arranged in the second direction, and the two first trench walls are slope structures gradually expanding upward from the trench bottom of the isolation trench.
8. The semiconductor laser according to any one of claims 1 to 7, wherein the isolation trench includes two second trench walls oppositely arranged along a first direction, and the two second trench walls are symmetrically arranged and have a stepped structure;
the width between the different steps of the two second groove walls is sequentially increased from the upward direction of the groove bottom of the isolation groove.
9. A semiconductor laser as claimed in claim 3 wherein the number of the extended waveguide structure is one, the extended waveguide structure being disposed proximate the reflective facets; the expansion waveguide structure is divided into two ridge waveguide structures which are arranged at intervals;
or the number of the expansion waveguide structures is two, wherein one of the expansion waveguide structures is arranged close to the light emergent cavity surface, and the other expansion waveguide structure is arranged close to the reflecting cavity surface; the two expansion waveguide structures are separated into three ridge waveguide structures which are arranged at intervals.
10. A method of fabricating a semiconductor laser device, for fabricating the semiconductor laser device as claimed in any one of claims 1 to 9, comprising:
providing a substrate;
preparing an epitaxial layer on one side of the substrate;
patterning the epitaxial layer to form a ridge waveguide structure and an extension waveguide structure;
forming the isolation groove in the region where the extension waveguide structure is located;
and forming a conductive function layer covering the isolation groove on the epitaxial layer.
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| CN202210720757.2A CN114825031B (en) | 2022-06-24 | 2022-06-24 | Semiconductor laser and preparation method thereof |
| PCT/CN2022/122615 WO2023245908A1 (en) | 2022-06-24 | 2022-09-29 | Semiconductor laser and preparation method therefor |
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| CN202210720757.2A CN114825031B (en) | 2022-06-24 | 2022-06-24 | Semiconductor laser and preparation method thereof |
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| JPH04159784A (en) * | 1990-10-23 | 1992-06-02 | Sumitomo Electric Ind Ltd | Semiconductor light emitting element and manufacture thereof |
| US5311539A (en) * | 1992-11-25 | 1994-05-10 | International Business Machines Corporation | Roughened sidewall ridge for high power fundamental mode semiconductor ridge waveguide laser operation |
| US6327288B1 (en) * | 1999-03-05 | 2001-12-04 | Lumileds Lighting, U.S., Llc | Buried heterostructure for lasers and light emitting diodes |
| KR100495220B1 (en) * | 2003-06-25 | 2005-06-14 | 삼성전기주식회사 | Semiconductor Laser Diode Comprising Higher Order Mode Absorb Control Layers |
| CN102324696B (en) * | 2011-09-15 | 2012-11-07 | 中国科学院长春光学精密机械与物理研究所 | Bragg refractive waveguide edge transmitting semiconductor laser with low horizontal divergence angle |
| CN106451075A (en) * | 2016-10-31 | 2017-02-22 | 苏州长光华芯光电技术有限公司 | Semiconductor laser chip and preparation method thereof |
| CN206542066U (en) * | 2017-02-28 | 2017-10-03 | 武汉光迅科技股份有限公司 | A kind of edge emitting high speed semiconductor laser chip |
| CN211265970U (en) * | 2020-03-25 | 2020-08-14 | 度亘激光技术（苏州）有限公司 | Waveguide structure of semiconductor laser |
| CN114552384A (en) * | 2020-11-27 | 2022-05-27 | 山东华光光电子股份有限公司 | Semiconductor laser device for realizing fundamental mode lasing by changing local lateral refractive index and preparation method thereof |
| CN113594854A (en) * | 2021-07-05 | 2021-11-02 | 威科赛乐微电子股份有限公司 | Edge-emitting semiconductor laser |
| CN114498299B (en) * | 2022-01-21 | 2023-01-31 | 度亘激光技术（苏州）有限公司 | Semiconductor device and preparation method thereof |
| CN114825031B (en) * | 2022-06-24 | 2022-09-23 | 度亘激光技术（苏州）有限公司 | Semiconductor laser and preparation method thereof |
| CN217469101U (en) * | 2022-06-24 | 2022-09-20 | 度亘激光技术（苏州）有限公司 | Ridge waveguide structure and laser |
| CN114825045B (en) * | 2022-06-24 | 2022-09-23 | 度亘激光技术（苏州）有限公司 | Anti-reflection laser and preparation method thereof |
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