Narrow linewidth high-power laser and preparation method thereof

Abstract

The present invention provides a narrow-linewidth, high-power laser and a method for fabricating the same. The laser comprises: a substrate; a laser region formed on the substrate, flanked by amplifier regions and wavelength-stabilizing regions; a laser region ridge waveguide formed on the laser region; an amplifier region tapered waveguide formed on the amplifier region; a wavelength-stabilizing region ridge waveguide formed on the wavelength-stabilizing region; and electrical isolation trenches between the laser region, amplifier region, wavelength-stabilizing region, and the laser region ridge waveguide, amplifier region tapered waveguide, and wavelength-stabilizing region ridge waveguide. The present invention utilizes the tapered amplifier, wavelength stabilizer, and electrical isolation trenches between the functional regions to achieve high power, narrow linewidth, and stable wavelength control, providing a solution to existing problems with pump light sources.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor optoelectronics, and in particular to a narrow-linewidth high-power laser and a preparation method thereof. Background Art

[0002] Semiconductor lasers, with their advantages of small size and high efficiency, are widely used in optical communications, storage, laser displays, and pump light sources. However, as pump light sources, high-power lasers have the disadvantage of having a broad laser spectrum that varies significantly with the laser's operating temperature and current, deviating from the absorption peak of the pumped material. This can lead to reduced pumping efficiency or even pump failure. Summary of the Invention

[0003] (1) Technical issues to be resolved

[0004] In view of this, the present invention provides a narrow-linewidth, high-power laser and a preparation method thereof, which adopts a tapered amplifier structure design to increase the wavelength stabilization region to prevent the laser wavelength from changing with temperature. At the same time, the wavelength stabilization increases the optical feedback length and can reduce the linewidth to solve or partially solve the above-mentioned problems.

[0005] (2) Technical solution

[0006] On one hand, the present invention provides a narrow-linewidth, high-power laser, comprising: a substrate; a laser region formed on the substrate, with amplifier regions and wavelength stabilization regions on both sides of the laser region; a laser region ridge waveguide formed on the laser region; an amplifier region tapered waveguide formed on the amplifier region; a wavelength stabilization region ridge waveguide formed on the wavelength stabilization region; an electrical isolation trench between the laser region, the amplifier region, and the wavelength stabilization region; and the electrical isolation trench between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide.

[0007] Optionally, the top of the tapered waveguide in the amplifier region is close to the ridge waveguide in the laser region.

[0008] Optionally, the bandgap wavelength of the wavelength stabilization region is smaller than the bandgap wavelength of the laser region.

[0009] Optionally, the laser region is the first active layer; the amplifier region is the second active layer; and the wavelength stabilization region is the passive layer; wherein a grating is engraved on the surface of the first active layer.

[0010] Optionally, a buffer layer made of the same material as the substrate is further included between the substrate and the laser region, the amplifier region and the wavelength stabilization region.

[0011] Another aspect of the present invention provides a method for preparing a narrow-linewidth high-power laser, comprising: sequentially forming a buffer layer and an active material layer on a substrate; removing the active material layer in a wavelength stabilization region and butt-growing a passive material layer; fabricating a grating on the active material layer in the laser region; sequentially growing a cladding layer and a contact layer on the active material layer and the passive material layer; fabricating a laser region ridge waveguide, an amplifier region tapered waveguide, and a wavelength stabilization region ridge waveguide from the cladding and the contact layer; removing the contact layer at the contact boundary between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide, and implanting ions to form an electrical isolation trench; fabricating P-type electrodes on the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide; thinning the lower portion of the substrate, and fabricating an N-type electrode on the lower portion of the substrate.

[0012] Optionally, removing the active material layer in the wavelength stabilization area and dockingly growing the passive material layer includes: covering the active material layer in the laser area and the amplifier area with a silicon dioxide mask, selectively etching and removing the active material layer in the wavelength stabilization area; and dockingly growing the passive material layer in the wavelength stabilization area using MOCVD.

[0013] Optionally, the cladding and the contact layer are formed into a ridge waveguide in the laser region, a tapered waveguide in the amplifier region, and a ridge waveguide in the wavelength stabilization region, including: using a photoresist mask to photoetch a ridge waveguide pattern on the surface of the contact layer above the laser region and the wavelength stabilization region, and photoetching a tapered waveguide on the surface of the contact layer above the amplifier region; and using a first etching solution and a second etching solution to successively etch the cladding and the contact layer to prepare the ridge waveguide in the laser region, the tapered waveguide in the amplifier region, and the ridge waveguide in the wavelength stabilization region.

[0014] Optionally, sequentially using a first etching solution and a second etching solution to etch the cladding and the contact layer includes: preparing the first etching solution according to Br2:HBr:H2O=1:25:80, and etching for a first preset time; preparing the second etching solution according to HCl:H2O=9:1, and etching for a second preset time; wherein the first preset time is shorter than the second preset time.

[0015] Optionally, removing the contact layer at the contact boundary between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide, and implanting ions to form an electrical isolation groove includes: photolithographically patterning an isolation groove in the contact layer at the contact boundary between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide; preparing a third etching solution according to H2SiO4:H2O2:H2O=3:1:1, etching to the active material layer and the passive material layer to form an isolation groove; and implanting He ions into the isolation groove to form the electrical isolation groove.

[0016] (3) Beneficial effects

[0017] The present invention provides a narrow-linewidth, high-power laser and its fabrication method. A tapered, large-light-field laser structure is designed to improve the near-field mode, increase the luminous area, and reduce the output optical power density, thereby increasing the output power. Electrothermal isolation technology is employed to achieve separate current control of the main oscillation region and the tapered amplification region. This prevents high-order side films generated by the excitation within the ridge waveguide from affecting the mode distribution in the tapered amplification region when the shared electrode current increases to a certain value. It also prevents a small portion of light reflected back into the cavity from oscillating and forming high-order modes within the cavity. A wavelength-stabilizing region is designed to stabilize the wavelength through current control, preventing wavelength drift with changes in laser temperature. The wavelength-stabilizing region also increases the optical feedback length, thereby narrowing the linewidth.

[0018] The present invention can achieve the effects of high power, narrow linewidth and wavelength stability control through a tapered amplifier, a wavelength stabilizer and special electrical isolation technology for each functional area, and provides a solution to the problems existing in current pump light sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The schematic diagram of the structure of the narrow linewidth high-power laser provided by the present invention is shown;

[0020] Figure 2 The following schematically shows a flow chart for preparing the narrow linewidth high-power laser provided by the present invention. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] Figure 1 The schematic diagram shows the structure of the narrow linewidth high-power laser provided by the present invention.

[0024] like Figure 1As shown, the present invention provides a narrow linewidth high-power laser, comprising: a substrate; a laser region formed on the substrate, with amplifier regions and wavelength stabilization regions on both sides of the laser region; a laser region ridge waveguide formed on the laser region; an amplifier region tapered waveguide formed on the amplifier region; and a wavelength stabilization region ridge waveguide formed on the wavelength stabilization region.

[0025] In one embodiment of the present invention, the narrow linewidth high power laser provided by the present invention is divided into three functional areas, such as Figure 1 As shown, the laser region 01, the wavelength stabilization region 02, and the amplifier region 03 are formed. The laser region 01 is formed in the middle portion of the substrate 10, with the wavelength stabilization region 02 and the amplifier region 03 adjacent to each other on either side. A laser region ridge waveguide is formed on the laser region 01, an upper wavelength stabilization region ridge waveguide is formed on the wavelength stabilization region 02, and an amplifier region tapered waveguide is formed on the amplifier region 03. The present invention designs a tapered, large-field laser structure to improve the near-field mode, increase the light-emitting area, and reduce the output optical power density, thereby increasing the output power.

[0026] Furthermore, the cone top of the tapered waveguide in the amplifier region is close to the ridge waveguide in the laser region; an electrical isolation groove is provided between the laser region, the amplifier region, and the wavelength stabilization region; and the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide also have the same electrical isolation groove. The present invention designs electrical isolation grooves for each functional region and adopts electrothermal isolation technology to achieve separate current control of the main oscillation region (laser region) and the tapered amplifier region of the laser, preventing the high-order side films generated by the excitation in the ridge waveguide from affecting the mode distribution of the tapered amplification region when the common electrode current increases to a certain value, while also preventing a small portion of the light reflected back into the cavity from oscillating in the cavity to form high-order modes. The wavelength stabilization region is designed to stabilize the wavelength through current control, preventing the wavelength from drifting with changes in the laser temperature. At the same time, the wavelength stabilization region has the function of increasing the optical feedback length, which can narrow the linewidth.

[0027] In another embodiment of the present invention, the bandgap wavelength of the wavelength stabilization region is smaller than the bandgap wavelength of the laser region. Based on this, the present invention achieves the purpose of preventing the laser from being absorbed in the wavelength stabilization region and preventing the power from decreasing.

[0028] In another embodiment of the present invention, the laser region is the first active layer; the amplifier region is the second active layer; and the wavelength stabilization region is the passive layer. A grating is engraved on the surface of the first active layer. Optionally, the first and second active layers utilize the same active material, wherein the grating may be provided on the surface of the first active layer located in the laser region. The passive layer utilizes a passive material. For example, the active material may be InGaAs / GaAs compressively strained quantum wells, and the passive material may be AlGaAs.

[0029] In another embodiment of the present invention, a buffer layer made of the same substrate material is further included between the substrate and the laser, amplifier, and wavelength stabilization regions. This buffer layer, made of the same substrate material, acts as a buffer for the subsequently grown materials of the laser, amplifier, and wavelength stabilization regions, thereby improving the quality of the materials grown therein. Optionally, the buffer layer can be doped differently as needed.

[0030] The present invention also provides a method for preparing the narrow linewidth high-power laser, comprising:

[0031] Operation S201: forming a buffer layer and an active material layer on a substrate in sequence;

[0032] Operation S202 , removing the active material layer in the wavelength stabilization region and butt-growing a passive material layer;

[0033] Operation S203: fabricating a grating on the active material layer of the laser region;

[0034] Operation S204: sequentially growing a cladding layer and a contact layer on the active material layer and the passive material layer;

[0035] Operation S205: forming the cladding layer and the contact layer into a laser region ridge waveguide, an amplifier region tapered waveguide, and a wavelength stabilization region ridge waveguide;

[0036] Operation S206: removing the contact layer at the boundary between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide, and implanting ions to form an electrical isolation trench;

[0037] Operation S207: forming a P-type electrode on the ridge waveguide in the laser region, the tapered waveguide in the amplifier region, and the ridge waveguide in the wavelength stabilization region;

[0038] In operation S208 , the lower portion of the substrate is thinned, and an N-type electrode is formed on the lower portion of the substrate.

[0039] Operation S202 includes: covering the active material layers of the laser region and the amplifier region with a silicon dioxide mask, selectively etching away the active material layer of the wavelength stabilization region; and butt-growing the passive material layer of the wavelength stabilization region using MOCVD.

[0040] Operation S205 includes: using a photoresist mask to photoetch a ridge waveguide pattern on the surface of the contact layer above the laser region and the wavelength stabilization region, and photoetching a tapered waveguide on the surface of the contact layer above the amplifier region; and sequentially etching the cladding and contact layer using a first etching solution and a second etching solution to produce a laser region ridge waveguide, an amplifier region tapered waveguide, and a wavelength stabilization region ridge waveguide. The sequential etching of the cladding and contact layer using the first etching solution and the second etching solution includes: preparing the first etching solution with a ratio of Br2:HBr:H2O = 1:25:80 for a first preset time; and preparing the second etching solution with a ratio of HCl:H2O = 9:1 for a second preset time; wherein the first preset time is shorter than the second preset time.

[0041] Operation S206 includes: photolithographically forming an isolation trench pattern in the contact layer at the interface between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide; preparing a third etching solution with a ratio of H2SiO4:H2O2:H2O=3:1:1, etching the active material layer and the passive material layer to form an isolation trench; and performing He ion implantation into the isolation trench to form an electrical isolation trench.

[0042] In one embodiment of the present invention, the specific steps of the method for preparing the narrow linewidth high-power laser are as follows:

[0043] (1) An N-type gallium arsenide substrate 10 is selected, and an AlGaAs buffer layer 20 and an active material layer 30 are sequentially grown on the substrate 10 by metal organic chemical vapor deposition (MOCVD). The active material layer is two InGaAs / GaAs compressively strained quantum wells, and the gain wavelength of the quantum well is around 960 nm. The quantum wells are loaded in a GaAs / AlGaAs optical waveguide layer, and the outside of the optical waveguide layer is an AlGaAs optical confinement layer.

[0044] (2) The active material layer 30 outside the laser region and the amplifier region is selectively etched away through a silicon dioxide mask, and a wavelength stabilization region passive material layer 40 is grown by MOCVD. The passive material layer 40 is an AlGaAs passive material.

[0045] (3) A grating 50 is made on the active layer material layer 30 of the laser region. The grating 50 is a 1 / 4 wavelength phase shift grating.

[0046] (4) The cladding layer 60 and the contact layer 70 are grown in sequence. The cladding layer 60 is made of AlGaAs material, and the contact layer 70 is made of GaAs material.

[0047] (5) Using a photoresist mask, the patterns of the ridge waveguide and the tapered amplifier are photoetched on the active layer material layer 30 and the passive material layer 40. A 1 μm photoresist is used to photoetch a 3 μm strip mask. The waveguide structures are successively produced using etching solutions Br2:HBr:H2O=1:25:80 (etching time is 40 seconds) and HCl:H2O=9:1 (etching time is 3 minutes). They are a ridge waveguide in the laser area, a tapered waveguide in the amplifier area, and a ridge waveguide in the wavelength stabilization area.

[0048] (6) An isolation groove pattern is formed on the contact layer 70 of the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide using a 3 μm thick photoresist. The pattern is located at the junction of the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide. The pattern is etched for 10 seconds using an etching solution of H2SiO4:H2O2:H2O=3:1:1 to form an electrical isolation groove 80 (with a width of 30 μm) between the regions. At the same time, He ions are implanted into the isolation groove with an implantation energy of 200 KeV and an implantation dose of 10 14 cm -2 The amplifier, laser, and wavelength stabilizer are electrically isolated from each other to prevent crosstalk between the functional areas.

[0049] (7) Sputtering equipment and photolithography technology are used to produce P-type electrodes for the laser zone ridge waveguide, the amplifier zone tapered waveguide, and the wavelength stabilization zone ridge waveguide.

[0050] (8) After the back side of the substrate 10 is thinned, a large-area N-electrode is produced to complete the chip preparation. The final laser lasing wavelength is 976nm and the line width is less than 1nm.

[0051] In the description of the present invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", "up", "down", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0052] Throughout the drawings, identical elements are denoted by identical or similar reference numerals. Conventional structures or configurations are omitted where they may obscure the understanding of this disclosure. The shapes, sizes, and positional relationships of components in the drawings do not reflect actual size, proportion, or positional relationships. In addition, in the claims, any reference signs placed between parentheses should not be construed as limitations of the claims.

[0053] Similarly, in order to streamline the present disclosure and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" and the like mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in an appropriate manner.

[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0055] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A narrow linewidth high-power laser, characterized in that: include: substrate; A laser region is formed on the substrate, with amplifier regions and wavelength stabilization regions on both sides of the laser region; A laser region ridge waveguide is formed on the laser region; an amplifier region tapered waveguide formed on the amplifier region; A wavelength stabilization region ridge waveguide is formed on the wavelength stabilization region; There is an electrical isolation trench between the laser region, the amplifier region, and the wavelength stabilization region; The electrical isolation groove is provided between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide.

2. The laser according to claim 1, characterized in that The cone top of the tapered waveguide in the amplifier region is close to the ridge waveguide in the laser region.

3. The laser according to claim 1, characterized in that The bandgap wavelength of the wavelength stabilization region is smaller than the bandgap wavelength of the laser region.

4. The laser according to claim 1, characterized in that The laser region is the first active layer; the amplifier region is the second active layer; the wavelength stabilization region is the passive layer; wherein a grating is engraved on the surface of the first active layer.

5. The laser according to claim 1, characterized in that A buffer layer made of the same material as the substrate is further included between the substrate and the laser region, the amplifier region and the wavelength stabilization region.

6. A method for preparing a narrow linewidth high-power laser according to any one of claims 1 to 5, characterized in that: include: forming a buffer layer and an active material layer on the substrate in sequence; removing the active material layer in the wavelength stabilization region and butt-growing a passive material layer; Fabricating a grating on the active material layer of the laser region; sequentially growing a cladding layer and a contact layer on the active material layer and the passive material layer; The cladding layer and the contact layer are made into the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide; Removing contact layers at the boundaries of the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide, and implanting ions to form an electrical isolation trench; Fabricating P-type electrodes on the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide; The lower portion of the substrate is thinned, and an N-type electrode is prepared on the lower portion of the substrate.

7. The preparation method according to claim 6, characterized in that The step of removing the active material layer in the wavelength stabilization region and butt-growing the passive material layer comprises: Covering the active material layers of the laser region and the amplifier region with a silicon dioxide mask, and selectively etching away the active material layer of the wavelength stabilization region; The passive material layer of the wavelength stabilization region is butt-grown by MOCVD.

8. The preparation method according to claim 6, characterized in that The step of manufacturing the cladding layer and the contact layer into the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide comprises: Using a photoresist mask, photoetching a ridge waveguide pattern on the surface of the contact layer above the laser region and the wavelength stabilization region, and photoetching a tapered waveguide on the surface of the contact layer above the amplifier region; The cladding layer and the contact layer are corroded by the first corrosive liquid and the second corrosive liquid in sequence to prepare the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide.

9. The preparation method according to claim 8, characterized in that The method of sequentially etching the cladding layer and the contact layer using the first etching solution and the second etching solution comprises: The first etching solution is prepared according to the ratio of Br2:HBr:H2O=1:25:80, and the etching time is the first preset time; The second etching solution is prepared according to the ratio of HCl:H2O=9:1, and the etching time is the second preset time; wherein, the first preset time is shorter than the second preset time.

10. The preparation method according to claim 6, characterized in that The removing of the contact layer at the boundary between the laser region ridge waveguide, the amplifier region tapered waveguide and the wavelength stabilization region ridge waveguide, and the ion implantation to form the electrical isolation groove comprises: Photolithographically forming an isolation groove pattern in the contact layer at the interface between the laser region ridge waveguide, the amplifier region tapered waveguide, and the wavelength stabilization region ridge waveguide; A third etching solution is prepared according to the ratio of H2SiO4:H2O2:H2O=3:1:1, and the solution is used to etch the active material layer and the passive material layer to form an isolation trench; The isolation trench is implanted with He ions to obtain an electrical isolation trench.

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