CN117424072A - Semiconductor laser with on-chip filter structure and preparation method thereof - Google Patents

Semiconductor laser with on-chip filter structure and preparation method thereof Download PDF

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Publication number
CN117424072A
CN117424072A CN202311595285.3A CN202311595285A CN117424072A CN 117424072 A CN117424072 A CN 117424072A CN 202311595285 A CN202311595285 A CN 202311595285A CN 117424072 A CN117424072 A CN 117424072A
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layer
semiconductor laser
tooth
type
ridge
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Chinese (zh)
Inventor
石建美
牛智川
杨成奥
徐应强
张宇
倪海桥
陈益航
王天放
余红光
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Institute of Semiconductors of CAS
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Institute of Semiconductors of CAS
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Priority to CN202311595285.3A priority Critical patent/CN117424072A/en
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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
    • H01S5/2004—Confining in the direction perpendicular to the layer structure
    • 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
    • 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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  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

The invention provides a semiconductor laser with an on-chip filter structure, comprising: the semiconductor laser comprises an N-face electrode, an N-type substrate, a buffer layer, an N-type limiting layer, a lower waveguide layer, an active region, an upper waveguide layer and a P-type limiting layer which are sequentially stacked from bottom to top, wherein the middle part of the P-type limiting layer is in a boss shape, step structures are arranged on two sides of the P-type limiting layer, a cover layer covers the upper surface of the boss shape, insulating layers cover the upper surface and the side surfaces of the step structures, the exposed areas of the cover layer and the insulating layers are covered with a P-face electrode layer, and a ridge bar of the semiconductor laser is formed by the middle protruding area of the P-type limiting layer and the cover layer; the groove structure is formed in the ridge and comprises a plurality of tooth-shaped grooves and a plurality of strip-shaped grooves, and the tooth-shaped grooves and the strip-shaped grooves are all arranged along the light emitting direction of the semiconductor laser. The invention can realize high power output and effectively improve the lateral far field characteristic.

Description

Semiconductor laser with on-chip filter structure and preparation method thereof
Technical Field
The invention relates to the technical field of semiconductor lasers, in particular to a semiconductor laser with an on-chip filter structure and a preparation method thereof.
Background
The semiconductor laser has the advantages of high efficiency, compactness, low cost, long service life, wide wavelength range, easy integration and the like, and is an ideal light source in various fields such as pumping, laser surgery, optical fiber communication, laser radar and the like. In recent years, to meet market demands, how to further increase the brightness of semiconductor lasers, i.e., increase output power and reduce beam divergence, has become a research and development hot spot.
The common high-power ridge semiconductor laser has a large number of lateral modes, has typical multi-lobe and large-divergence lateral far field, and the quality of a light beam is further deteriorated due to the increase of working current, so that the coupling difficulty is increased during application, and the subsequent complex optical design is required. The common methods of angle cavity, external cavity, phase control structure, etc. have certain bottlenecks and limitations in terms of design, process and power.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a semiconductor laser having an on-chip filtering structure and a method for fabricating the same, which can achieve high power output and effectively improve lateral far field characteristics.
One aspect of the present invention provides a semiconductor laser having an on-chip filter structure, comprising: the semiconductor laser comprises an N-face electrode, an N-type substrate, a buffer layer, an N-type limiting layer, a lower waveguide layer, an active region, an upper waveguide layer and a P-type limiting layer which are sequentially stacked from bottom to top, wherein the middle part of the P-type limiting layer is in a boss shape, step structures are arranged on two sides of the P-type limiting layer, a cover layer covers the upper surface of the boss shape, insulating layers cover the upper surface and the side surfaces of the step structures, the exposed areas of the cover layer and the insulating layers are covered with a P-face electrode layer, and a ridge bar of the semiconductor laser is formed by the middle protruding area of the P-type limiting layer and the cover layer; the groove structure is formed in the ridge and comprises a plurality of tooth-shaped grooves and a plurality of strip-shaped grooves, and the tooth-shaped grooves and the strip-shaped grooves are all arranged along the light emitting direction of the semiconductor laser.
In some exemplary embodiments of the present invention, the tooth-like grooves are opened vertically downward from the contact surface of the cap layer and the P-side electrode layer, with the lowest position opened between the contact surface of the P-type confinement layer and the cap layer and the contact surface of the P-type confinement layer and the upper waveguide layer, with a depth of 1 to 3 μm.
In some exemplary embodiments of the present invention, the tooth-shaped grooves 121 are disposed on a side of the ridge near the front facet of the semiconductor laser, on a side of the ridge near the back facet of the semiconductor laser, and/or on both sides of the upper surface of the ridge, and are symmetrical with respect to a lateral center line and/or a longitudinal center line of the light exit facet of the semiconductor laser.
In some exemplary embodiments of the present invention, the tooth-like grooves are arranged periodically along the light emitting direction of the semiconductor laser; wherein, each cycle has fixed clearance, contains the independent tooth form slot of a plurality of same cross sectional shapes in each cycle, and cross sectional shape includes triangle-shaped, semi-circular, half ellipse. In some exemplary embodiments of the present invention, the plurality of stripe-shaped trenches are opened vertically downward from the contact surface of the cap layer and the P-side electrode layer, and the opened lowest position is between the contact surface of the P-type confinement layer and the cap layer and the contact surface of the P-type confinement layer and the upper waveguide layer, and the opened depth is 1-3 μm.
In some exemplary embodiments of the present invention, the stripe grooves are arranged in a straight line, and are formed on two side edges of the upper surface of the ridge along the light emitting direction of the semiconductor laser, and are symmetrical with respect to the transverse center line and/or the longitudinal center line of the light emitting cavity surface of the semiconductor laser, and the plurality of stripe grooves are provided with a space on one side of the tooth bottoms of the plurality of tooth grooves, and the minimum space is zero.
In some exemplary embodiments of the present invention, a span value between both sides of the groove at any one of the tooth-shaped grooves is set to 0.5 to 10 μm; the span value between the two sides of any one of the strip-shaped grooves is set to be 0.5-10 mu m.
In some exemplary embodiments of the present invention, the ratio of etched portions to unetched portions of the plurality of tooth-like grooves ranges from 2:8 to 8:2.
In some exemplary embodiments of the invention, the material of the P-side electrode comprises Ti, pt, au; the material of the cover layer is P-type heavily doped GaSb; the insulating layer is made of SiO 2 Or Si (or) 3 N 4 The method comprises the steps of carrying out a first treatment on the surface of the The material of the P-type limiting layer is P-type doped Al 0.5 GaAsSb; the active region comprises n quantum wells and n-1 barrier layers, wherein n is a positive integer, and the material of the quantum wells is In 0.18 The material of the barrier layer is Al 0.25 GaAsSb; the upper waveguide layer and the lower waveguide layer are made of the same material and are undoped Al 0.25 GaAsSb; the material of the N-type limiting layer is N-type doped Al 0.5 GaAsSb; the buffer layer is made of N-type doped GaSb; the N-type substrate is made of GaSb; and the material of the N-side electrode includes Ni, auGe, au.
Another aspect of the present invention provides a method for fabricating a semiconductor laser having an on-chip filtering structure, including: step S1, growing an epitaxial structure, and sequentially growing a buffer layer, an N-type limiting layer, a lower waveguide layer, an active region, an upper waveguide layer, a P-type limiting layer and a cover layer on an N-type substrate; step S2, etching off the cover layer and part of the P-type limiting layer on two sides of the mesa of the semiconductor laser to form ridge strips; step S3, respectively etching a toothed groove and a strip-shaped groove in the groove structure in the ridge; step S4, an insulating layer is grown on the upper surface and the outer side surface of the step structure of the P-type limiting layer; and S5, forming a P-surface electrode on the ridge and the insulating layer, and forming an N-surface electrode on the back surface of the N-type substrate after thinning and polishing.
The semiconductor laser with the on-chip filter structure and the preparation method thereof provided by the embodiment of the invention have the following beneficial effects:
(1) The etching proportion can be flexibly adjusted, the tooth-shaped groove positions are adjusted by combining different ridge widths, and the edge groove positions are adjusted according to the carrier density distribution peak value positions, so that accurate regulation and control are performed.
(2) Multiple scattering and reflection occur at the groove in the transmission process of the light field in the high-order mode, and the energy of the fundamental mode is hardly influenced by the toothed structure, so that the near-field beam waist is contracted, the mode gain regulation and control are realized, the lasing threshold of the high-order mode is increased, and the lateral divergence is reduced.
(3) The tooth-shaped grooves can also effectively improve lateral carrier accumulation and lateral current diffusion, realize double inhibition with the strip-shaped grooves, relieve the problem of high-order mode extra gain caused by lateral carrier accumulation at the edge of the ridge, improve injection efficiency, reduce threshold current and realize high-brightness output.
(4) The structure can reduce the thermal gradient in the slow axis direction and reduce the filiform effect. The single transverse mode output under a wider output aperture can be realized by applying the single transverse mode output in the narrow ridge waveguide, the working current range of the single transverse mode output is increased, and the device power is improved.
(5) As a whole, the groove structure formed by the toothed grooves and the strip grooves has wide application range, can be applied to narrow ridge strips and wide ridge strips, and can be combined with a DFB structure, a per structure and the like to be monolithically integrated into a single device, so that a high-mode purity high-power device is realized.
(6) The groove structure has low requirements on lithography precision and can be formed by synchronous lithography with a large-size pattern.
Drawings
Fig. 1 schematically shows an effect diagram of a semiconductor laser with an on-chip filtering structure according to an embodiment of the present invention;
fig. 2 schematically illustrates a cross-sectional view of a semiconductor laser having an on-chip filtering structure in accordance with an embodiment of the present invention;
fig. 3 schematically illustrates a top view of a semiconductor laser having an on-chip filtering structure in accordance with an embodiment of the present invention;
fig. 4 schematically illustrates a partial view of a semiconductor laser having an on-chip filtering structure in accordance with an embodiment of the present invention;
FIG. 5A schematically illustrates the lateral far field of a semiconductor laser without an on-chip filtering structure;
fig. 5B schematically illustrates a lateral far field of a semiconductor laser with an on-chip filtering structure in accordance with an embodiment of the present invention;
fig. 6 schematically illustrates a process flow of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Fig. 1 schematically illustrates an effect diagram of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention, fig. 2 schematically illustrates a cross-sectional view of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention, and fig. 3 schematically illustrates a top view of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention.
As shown in fig. 1, an effect diagram of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention is schematically shown, fig. 2 is an A-A plane cross-sectional view of the semiconductor laser shown in fig. 1, and fig. 3 is a top view of the semiconductor laser shown in fig. 1. Referring to fig. 1 to 3, in the present embodiment, a semiconductor laser having an on-chip filtering structure includes: the semiconductor laser comprises an N-face electrode 11, an N-type substrate 10, a buffer layer 9, an N-type limiting layer 8, a lower waveguide layer 7, an active region 6, an upper waveguide layer 5 and a P-type limiting layer 4 which are sequentially stacked from bottom to top, wherein the middle part of the P-type limiting layer is in a boss shape, step structures are arranged on two sides of the P-type limiting layer, a cover layer 2 covers the upper surface of the boss shape, insulating layers 3 cover the upper surface and the side faces of the step structures, the exposed areas of the cover layer 2 and the insulating layers 3 are covered with P-face electrode layers 1, the protruding areas of the middle part of the P-type limiting layer 4 and the cover layer 2 form ridge bars of the semiconductor laser, and groove structures 12 are formed in the ridge bars. However, it should be appreciated by those skilled in the art that the trench structure 12 shown in any one of FIGS. 1-3 is merely exemplary and does not limit the location and shape of the trench structure 12. The composition, location, shape and function of trench structure 12 will be further described with reference to the following figures.
Referring now to fig. 3, in the illustrated example, the trench structure 12 includes a plurality of tooth-shaped trenches 121 and a plurality of stripe-shaped trenches 122, and the plurality of tooth-shaped trenches 121 and the plurality of stripe-shaped trenches 122 are all arranged along the light emitting direction of the semiconductor laser, as shown in fig. 3. Specifically, the arrangement direction of the plurality of tooth-shaped grooves 121 refers to the connection line direction between the center points of the interconnecting teeth in fig. 3, and the arrangement direction of the plurality of bar-shaped grooves 122 is the straight line direction of a continuous segment of bar-shaped grooves 122. The light-emitting direction is the direction in which light exits the semiconductor laser. The plurality of tooth-shaped grooves 121 and the plurality of strip-shaped grooves 122 are all arranged along the light emitting direction of the semiconductor laser, and the reflection and scattering surfaces of high-order mode transmission are increased, so that the high-order mode transmission has stronger filtering capability, and low-divergence output is realized on the premise of not affecting the output power of the original ridge waveguide.
In some examples, the tooth-like grooves 121 are disposed on a side of the ridge near the front facet of the semiconductor laser, on a side of the ridge near the back facet of the semiconductor laser, and/or on both sides of the upper surface of the ridge, and are symmetrical about a lateral centerline and/or a longitudinal centerline of the light exit facet of the semiconductor laser. This arrangement is to ensure that the tooth grooves 121 are symmetrically and uniformly arranged on the ridge stripe, and to better control the filtering.
In some examples, the tooth-like grooves 121 are arranged periodically along the light emitting direction of the semiconductor laser, with a fixed gap between each period, and each period contains a plurality of independent tooth-like grooves with the same cross-sectional shape, including but not limited to triangle, semicircle, and semi-ellipse. In the example shown in fig. 3, the toothed grooves 121 have 16 independent toothed grooves, each 4 independent toothed grooves are one period, each two periods are aligned in a row, and are respectively disposed on both sides of the ridge. It should be noted that 16 independent tooth-shaped grooves are only an example, and the number and the periodic arrangement of the tooth-shaped grooves 121 are not limited.
Referring to fig. 3, in the present embodiment, the stripe-shaped grooves 122 are disposed in a straight line, are formed on the two side edges of the upper surface of the ridge along the light emitting direction of the semiconductor laser, and are symmetrical with respect to the transverse center line and/or the longitudinal center line of the light emitting cavity surface of the semiconductor laser, and the arrangement purpose is the same as that of the tooth-shaped grooves 121, so that the description is omitted.
In some examples, a plurality of toothed grooves are etched, multiple scattering and reflection occur at the grooves in the transmission process of the light field of the higher-order mode, and the energy of the fundamental mode is hardly affected by the toothed structure, so that the near-field beam waist is contracted, the mode gain regulation is realized, the lasing threshold of the higher-order mode is increased, and the lateral divergence is reduced. The tooth-shaped grooves can also effectively improve lateral carrier accumulation and lateral current diffusion, realize double inhibition with the strip-shaped grooves, relieve the problem of high-order mode extra gain caused by lateral carrier accumulation at the edge of the ridge, improve injection efficiency, reduce threshold current and realize high-brightness output.
In some examples, the plurality of strip-shaped grooves 122 are spaced from the tooth bottom side of the plurality of tooth-shaped grooves 121, and the minimum spacing is zero. A minimum pitch of zero means that the tooth bottom of the tooth-like groove 121 coincides with the stripe-like groove 122, and also means that the stripe-like groove 122 cannot pass through the middle of the tooth-like groove 121.
With continued reference to fig. 3, in the present embodiment, L is the ridge width, D is the distance between the two side strip grooves 122, T is the width of the bottom of the independent tooth groove 121, and D is the distance between the top of the independent tooth groove 121 and the ridge edge. The distance D between the two side stripe grooves 122 is 9L/10 according to the lateral carrier distribution. The peak position of the first-order side mode is located at a distance L/4 from the ridge edge, the peak position of the second-order side mode is located at a distance L/6 from the ridge edge, and the peak positions of the third-order side mode are L/8 and 3L/8. Preferably, in order for the toothed groove 121 to better act on the first-order side mold, the distance d=l/4 between the tip of the individual toothed groove 121 and the ridge edge.
Fig. 4 schematically illustrates a partial view of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention, and fig. 4 is a partial view of the cross-sectional view illustrated in fig. 2.
As shown in fig. 4, a trench structure 12 within a ridge is shown. Fig. 4 is merely an example, and does not reflect a proportional relationship. In the present embodiment, d1 is the span between the two sides of any one of the tooth-shaped grooves 121, and d2 is the span between the two sides of any one of the strip-shaped grooves 122. In some examples, the d1, d2 settings are each in the range of 0.5-10 μm.
In some examples, the tooth-shaped grooves 121 are vertically and downwardly opened from the contact surface of the cap layer 2 and the P-side electrode layer 1, the lowest opened position is between the contact surface of the P-type confinement layer 4 and the cap layer 2 and the contact surface of the P-type confinement layer 4 and the upper waveguide layer 5, and the opening depth of the tooth-shaped grooves 121 is h1, and h1 is between 1 and 3 μm.
In some examples, the stripe trench 122 is opened vertically downward from the contact surface of the cap layer 2 and the P-side electrode layer 1, the lowest position of the opening is between the contact surface of the P-type confinement layer 4 and the cap layer 2 and the contact surface of the P-type confinement layer 4 and the upper waveguide layer 5, and the stripe trench 122 is opened to a depth h2, where h2 is between 1 and 3 μm.
Preferably, for the convenience of the process operation, generally, h1 and h2 may be set to the same value, but the present invention is not limited thereto.
In some examples, to ensure high loss in the higher order mode while reducing loss in the fundamental mode, the ratio of etched portions to unetched portions in the plurality of tooth-like trenches 121 ranges from 2:8 to 8:2.
With continued reference to fig. 2, in some examples, the material of the P-side electrode 1 includes Ti, pt, au; the material of the cover layer 2 is P-type heavily doped GaSb; the material of the insulating layer 3 comprises SiO 2 Or Si (or) 3 N 4 The method comprises the steps of carrying out a first treatment on the surface of the The material of the P-type limiting layer 4 is P-type doped Al 0.5 GaAsSb; the active region 6 comprises n quantum wells and n-1 barrier layers, wherein n is a positive integer, and the material of the quantum wells is In 0.18 The material of the barrier layer is Al 0.25 GaAsSb; the upper waveguide layer 5 and the lower waveguide layer 7 are made of the same material and are undoped Al 0.25 GaAsSb; the material of the N-type limiting layer 8 is N-type doped Al 0.5 GaAsSb; the material of the buffer layer 9 is N-type doped GaSb; the material of the N-type substrate 10 is GaSb; the material of the N-side electrode 11 includes Ni, auGe, au and the like.
Fig. 5A schematically illustrates a lateral far field of a semiconductor laser without an on-chip filtering structure, and fig. 5B schematically illustrates a lateral far field of a semiconductor laser with an on-chip filtering structure according to an embodiment of the present invention.
As shown in fig. 5A and 5B, the abscissa is the far-field divergence angle, and the ordinate is the relative intensity. It can be seen that a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention can significantly improve far-field divergence angle.
On the basis, the invention also discloses a preparation method of the semiconductor laser with the on-chip filtering structure.
Fig. 6 schematically illustrates a process flow of a semiconductor laser having an on-chip filtering structure according to an embodiment of the present invention.
As shown in fig. 6, in the present embodiment, a method for manufacturing a semiconductor laser having an on-chip filter structure includes:
in step S1, an epitaxial structure is grown, and a buffer layer 9, an N-type confinement layer 8, a lower waveguide layer 7, an active region 6, an upper waveguide layer 5, a P-type confinement layer 4, and a cap layer 2 are sequentially grown on an N-type substrate 10. And S2, etching off the cover layer 2 and part of the P-type limiting layer 4 on two sides of the semiconductor laser mesa to form a ridge.
Alternatively, the ridge may be formed by wet or Inductively Coupled Plasma (ICP) dry etching.
In step S3, the tooth-shaped trenches 121 and the stripe-shaped trenches 122 in the trench structure 12 are etched in the ridge, respectively.
Alternatively, the tooth-shaped trenches 121 and the stripe-shaped trenches 122 in the trench structure 12 may be formed by one-time photolithography and then by simultaneous etching, and the pattern transfer may be achieved by dry etching, which has an advantage in that vertical sidewalls of the structure may be formed.
In step S4, the insulating layer 3 is grown on the upper surface and the outer side of the step structure of the P-type confinement layer 4.
Alternatively, step S4 may grow the insulating layer using Metal Organic Chemical Vapor Deposition (MOCVD).
In step S5, the P-side electrode 1 is formed on the ridge stripe and the insulating layer 3, and the N-side electrode 11 is formed on the back surface of the N-type substrate 10 after thinning and polishing.
Alternatively, an ICP or Reactive Ion Etch (RIE) may be used to etch away the insulating layer on the ridge to avoid the trench structure to form an electrical implantation window. The P-side electrode 1 may be formed on the ridge stripe and the insulating layer 3 using a magnetron sputtering or electron beam evaporation process.
Optionally, after steps S1 to S5, cleaving the formed wafer into bars, plating an anti-reflection film and a high-reflection film on the bars corresponding to the front cavity surface and the back cavity surface of the semiconductor laser, respectively, and finally cleaving into individual dies and mounting the individual dies on a heat sink for testing. The wafer refers to a processed piece obtained by a series of processes such as photoetching, etching, electrode growth and the like after the epitaxial structure grows on the N-type substrate 10, and the single laser can be 500-1500 μm in size 2 . The antireflection film material can be Al 2 O 3 The high-reflection film material can adopt Si|SiO 2 。
In summary, according to the semiconductor laser with on-chip filtering structure and the method for manufacturing the same provided by the embodiments of the present invention, according to the near-field distribution characteristics of the laser, the fundamental mode energy is mainly concentrated in the center of the ridge, the high-order side mode distribution extends toward the edge, so that the etching ratio can be flexibly adjusted, the tooth-shaped groove positions can be adjusted according to the widths of the different ridge, and the edge groove positions can be adjusted according to the peak positions of the carrier density distribution, so as to perform precise adjustment. And on the basis of the ridge semiconductor laser, a plurality of toothed grooves are etched, multiple scattering and reflection occur at the grooves in the transmission process of the light field in the high-order mode, the energy of the fundamental mode is hardly influenced by the toothed structure, the beam waist of the near field is contracted, the mode gain regulation is realized, the lasing threshold of the high-order mode is increased, and therefore the lateral divergence is reduced. The tooth-shaped grooves can also effectively improve lateral carrier accumulation and lateral current diffusion, realize double inhibition with the strip-shaped grooves, relieve the problem of high-order mode extra gain caused by lateral carrier accumulation at the edge of the ridge, improve injection efficiency, reduce threshold current and realize high-brightness output.
Meanwhile, the structure can reduce the thermal gradient in the slow axis direction and reduce the filiform effect. The single transverse mode output under a wider output aperture can be realized by applying the single transverse mode output in the narrow ridge waveguide, the working current range of the single transverse mode output is increased, and the device power is improved. As a whole, the groove structure formed by the toothed grooves and the strip grooves has wide application range, can be applied to not only narrow ridge bars but also wide ridge bars, can be combined with a DFB structure, a per structure and the like to be monolithically integrated into a single device, and realizes a high-mode purity high-power device. In addition, the groove structure has low requirements on lithography precision and can be formed by synchronous lithography with a large-size pattern.
Thus, the semiconductor laser with the on-chip filter structure and the preparation method thereof are described. From this description, those skilled in the art will readily appreciate that the present invention is well within the framework of the following detailed description.
While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.

Claims (10)

1. A semiconductor laser having an on-chip filtering structure, comprising:
the semiconductor laser comprises an N-face electrode (11), an N-type substrate (10), a buffer layer (9), an N-type limiting layer (8), a lower waveguide layer (7), an active region (6), an upper waveguide layer (5) and a P-type limiting layer (4) which are sequentially stacked from bottom to top, wherein the middle part of the P-type limiting layer (4) is in a boss shape, step structures are arranged on two sides of the P-type limiting layer, a cover layer (2) covers the upper surface of the boss shape, insulating layers (3) cover the upper surface and the side surfaces of the step structures, P-face electrode layers (1) cover the exposed areas of the cover layer (2) and the insulating layers (3), and ridge strips of the semiconductor laser are formed by the middle protruding areas of the P-type limiting layer (4) and the cover layer (2);
the groove structure (12) is formed in the ridge and comprises a plurality of tooth-shaped grooves (121) and a plurality of strip-shaped grooves (122), and the tooth-shaped grooves (121) and the strip-shaped grooves (122) are all arranged along the light emitting direction of the semiconductor laser.
2. The semiconductor laser according to claim 1, characterized in that the tooth-like trench (121) opens vertically downwards from the contact surface of the cap layer (2) and the P-surface electrode layer (1), and the lowest position of the opening is between the contact surface of the P-type confinement layer (4) and the cap layer (2) and the contact surface of the P-type confinement layer (4) and the upper waveguide layer (5), and the opening depth is 1-3 μm.
3. A semiconductor laser according to claim 1, characterized in that the tooth-like grooves (121) are arranged on the side of the ridge close to the front facet of the semiconductor laser, on the side of the ridge close to the back facet of the semiconductor laser and/or on both sides of the upper surface of the ridge and are symmetrical with respect to the transverse and/or longitudinal centre line of the light exit facet of the semiconductor laser.
4. A semiconductor laser according to claim 3, wherein the tooth-like grooves (121) are arranged periodically along the light-emitting direction of the semiconductor laser; wherein,
there is a fixed gap between each cycle, and each cycle contains a plurality of independent toothed grooves with the same cross-sectional shape, wherein the cross-sectional shape comprises triangle, semicircle and semi-ellipse.
5. The semiconductor laser according to claim 1, wherein the plurality of stripe-shaped trenches (122) are opened vertically downward from the contact surface of the cap layer (2) and the P-surface electrode layer (1), and the lowest opened position is between the contact surface of the P-type confinement layer (4) and the cap layer (2) and the contact surface of the P-type confinement layer (4) and the upper waveguide layer (5), and the opened depth is 1-3 μm.
6. The semiconductor laser according to claim 5, wherein the stripe grooves (122) are arranged in a straight line, are formed on two side edges of the upper surface of the ridge along the light emitting direction of the semiconductor laser, and are symmetrical with respect to a transverse center line and/or a longitudinal center line of the light emitting cavity surface of the semiconductor laser, and the stripe grooves (122) are spaced from one side of the tooth bottoms of the tooth grooves (121) at a minimum spacing of zero.
7. The semiconductor laser according to claim 6, wherein a span value between both sides of the trench at any one of the tooth-like trenches (121) is set to 0.5 to 10 μm;
the span value between the two sides of any one of the strip-shaped grooves (122) is set to be 0.5-10 mu m.
8. The semiconductor laser of claim 7, wherein a ratio of etched portions to unetched portions of the plurality of tooth-like trenches (121) ranges from 2:8 to 8:2.
9. A semiconductor laser according to claim 1, characterized in that the material of the P-side electrode (1) comprises Ti, pt, au;
the material of the cover layer (2) is P-type heavily doped GaSb;
the material of the insulating layer (3) is SiO 2 Or Si (or) 3 N 4 ；
The material of the P-type limiting layer (4) is P-type doped Al 0.5 GaAsSb；
The active region (6) comprises n quantum wells and n-1 barrier layers, wherein n is a positive integer, and the material of the quantum wells is In 0.18 GaSb, the barrier layer is made of Al 0.25 GaAsSb；
The upper waveguide layer (5) and the lower waveguide layer (7) are made of the same material and are made of undoped Al 0.25 GaAsSb；
The material of the N-type limiting layer (8) is N-type doped Al 0.5 GaAsSb；
The buffer layer (9) is made of N-type doped GaSb;
the N-type substrate (10) is made of GaSb; and
the material of the N-face electrode (11) comprises Ni, auGe, au.
10. A method of manufacturing a semiconductor laser according to any one of claims 1 to 9, comprising:
step S1, growing an epitaxial structure, and sequentially growing a buffer layer (9), an N-type limiting layer (8), a lower waveguide layer (7), an active region (6), an upper waveguide layer (5), a P-type limiting layer (4) and a cover layer (2) on an N-type substrate (10);
step S2, etching off the cover layer (2) and part of the P-type limiting layer (4) on two sides of the semiconductor laser mesa to form ridge strips;
step S3, respectively etching tooth-shaped grooves (121) and strip-shaped grooves (122) in the groove structures (12) in the ridge;
step S4, an insulating layer (3) is grown on the upper surface and the outer side surface of the step structure of the P-type limiting layer (4);
and S5, forming a P-surface electrode (1) on the ridge and the insulating layer (3), and forming an N-surface electrode (11) on the back surface of the N-type substrate (10) after thinning and polishing.
CN202311595285.3A 2023-11-27 2023-11-27 Semiconductor laser with on-chip filter structure and preparation method thereof Pending CN117424072A (en)

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