CN219163905U - Heterogeneous integrated external cavity DBR semiconductor laser - Google Patents
Heterogeneous integrated external cavity DBR semiconductor laser Download PDFInfo
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- CN219163905U CN219163905U CN202320298516.3U CN202320298516U CN219163905U CN 219163905 U CN219163905 U CN 219163905U CN 202320298516 U CN202320298516 U CN 202320298516U CN 219163905 U CN219163905 U CN 219163905U
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Abstract
The utility model provides a heterogeneous integrated external cavity DBR semiconductor laser, belongs to the technical field of semiconductor lasers, and aims to solve the technical problems of high process requirements and large line width of an internal cavity DBR semiconductor narrow line width laser. The semiconductor laser comprises a laser chip and a PLC grating chip which are connected in a coupling way, wherein the PLC grating chip comprises a substrate, a lower cladding layer, a waveguide grating and an upper cladding layer are sequentially arranged on the substrate from bottom to top, and the waveguide grating consists of a mode spot converter, a straight waveguide and a Bragg grating which are integrated into a whole; the light-emitting surface of the laser chip is coupled with the end surface of the SSC spot converter. The utility model adopts the scheme of an F-P cavity structure and an external planar waveguide grating structure, and the external waveguide and the external Bragg waveguide grating are used for narrowing the linewidth of the inner cavity.
Description
Technical Field
The utility model belongs to the technical field of semiconductor lasers, and particularly relates to a heterogeneous integrated external cavity DBR semiconductor laser.
Background
At present, a Bragg grating is adopted for wavelength selection and narrow linewidth compression of a narrow linewidth semiconductor laser, and the narrow linewidth semiconductor laser is divided into an inner cavity narrow linewidth structure and an outer cavity narrow linewidth structure according to the difference of the grating on the position of a device. DFB and DBR cavity narrow linewidth semiconductor laser structures select the longitudinal modes within the cavity by introducing bragg gratings (bragg gratings). Wherein the grating of the DFB semiconductor laser is distributed throughout the cavity, the DBR semiconductor laser grating region is on only two sides (or one side) and is used only as a reflector, and the gain region has no grating, which is separate from the reflector. The structure is that the grating structure is directly manufactured on the semiconductor laser chip, and the gain region of the DBR semiconductor laser and the Bragg grating structure are the same substance. Distributed Bragg Reflector (DBR) cavity narrow linewidth semiconductor lasers are mostly III-V compound materials, such as: gaAs, inP, gaSb, etc., the refractive index of these III-V compound materials is much higher than that of SiO 2 、Si 3 N 4 The size of their corresponding semiconductor laser chips is typically in the order of microns, resulting in a large emission line width, for which a reduced grating period is required, which requires the preparation of more pairs of gratings over a potentially small length. However, processing ultraviolet lithography of less than microns is generally not completed, which requires electron beam lithography with higher precision and cost, resulting in higher manufacturing difficulties and costs. In addition, the linewidth of the semiconductor laser with the narrow inner cavity is generally above 100kHz, and the semiconductor laser cannot be applied to optical fiber communication.
Disclosure of Invention
Aiming at the technical problems of high requirements on the preparation process of the narrow linewidth laser of the inner cavity DBR semiconductor and large linewidth, the utility model provides a heterogeneous integrated outer cavity DBR semiconductor laser, which adopts the scheme of an F-P cavity structure and an external planar waveguide grating structure, and the linewidth of the inner cavity is narrowed through an external waveguide and an external Bragg waveguide grating.
In order to achieve the above purpose, the technical scheme of the utility model is realized as follows:
the heterogeneous integrated external cavity DBR semiconductor laser comprises a laser chip and a PLC grating chip which are connected in a coupling way, wherein the PLC grating chip comprises a substrate, a lower cladding layer, a waveguide grating and an upper cladding layer are sequentially arranged on the substrate from bottom to top, the waveguide grating consists of an integrated SSC (spot-size converter), a direct waveguide and a Bragg grating, and all the components are connected end to end; the light-emitting surface of the laser chip is coupled with the end surface of the spot-size converter.
The waveguide grating is SiO 2 Waveguide grating, siO 2 The refractive index of the waveguide grating is higher than the refractive index of the upper cladding layer and the lower cladding layer.
The laser chip is an F-P cavity laser, the structure of the laser chip is a narrow F-P cavity with a ridge waveguide width of 3-5 mu m, and the substrate material of the laser chip is InP, and the structure of the laser chip is shown in the following figure 2. The epitaxial structure of the laser chip is a large optical cavity waveguide structure, and the slow axis divergence angle is increased by increasing the size of the waveguide structure, so that the fast axis divergence angle of the laser chip is similar to the slow axis divergence angle.
The laser chip has an lasing wavelength of 1310nm or 1550nm, which satisfies a band for communication.
The non-light-emitting surface of the laser chip is plated with a high-reflection film, so that photons in the laser cavity are emitted from the light-emitting surface. Preferably, the reflectance of the highly reflective film is not less than 95%.
The light-emitting surface of the laser chip is plated with an antireflection film, so that photons in the laser cavity are easier to emit from the light-emitting surface. Preferably, the reflectance of the antireflection film is not more than 0.001%. The light emergent surface of the laser chip is a coupling surface with the PLC grating chip, and the lower the reflectivity of the surface is, the more favorable for the performance stability of the laser with the external cavity structure.
And the coupling surface of the coupling connection end of the PLC grating chip and the laser chip and the output end surface of the other end are plated with antireflection films. The anti-reflection film is prepared on the coupling surface of the PLC grating chip, so that photons emitted by the laser can enter the PLC grating chip more easily; and an antireflection film is prepared on the output end face of the PLC grating chip, namely the end face of one side where the Bragg grating is positioned, so that photons are easier to emit. Preferably, the reflectance of the antireflection film is not more than 0.001%.
The SSC mode spot converter in the PLC grating chip enables the mode spots emitted by the laser to be matched with the mode of the straight waveguide, and the coupling efficiency of the external cavity laser is improved.
The bragg grating in the PLC grating chip is used as a main wavelength selective structure, and the bragg wavelength of the bragg grating needs to be matched with the lasing wavelength of the laser chip.
The Bragg grating in the PLC grating chip is used as a main wavelength selection structure, and the Bragg grating parameters, such as grating period, grating duty ratio and the like, are determined according to actual process conditions. The high-order Bragg grating can be selected to increase the grating period, so that the preparation difficulty of a grating process is reduced.
And the PLC grating chip is connected with the tail fiber.
And a lens is arranged between the PLC grating chip and the tail fiber, and the PLC grating chip is coupled with the tail fiber through a lens group.
The wavelength of the light output by the semiconductor laser is selected by the SSC mode spot converter and the straight waveguide, and the length of the external cavity can be far longer than that of the semiconductor laser, so that the service life of the photon carrier in the external cavity can be prolonged by increasing the length of the external cavity from the consideration of an equivalent external cavity narrow linewidth model, and the linewidth of the laser is effectively reduced. In addition, wavelength narrowing can be achieved by selecting the wavelength through the Bragg grating structure.
The utility model has the beneficial effects that: the semiconductor laser with the F-P cavity structure is coupled with the PLC grating chip, the external cavity length is increased through the external straight waveguide, and the external Bragg waveguide grating is used for narrowing the inner cavity linewidth, so that the problems of secondary epitaxy and high-precision butt joint process in the homogeneous DBR semiconductor laser and large inner cavity narrow linewidth laser linewidth are solved. The structure has the advantages of simple and reliable structure, high integration level, low preparation cost and the like. The laser device has the advantages of providing a simple and reliable structural scheme for realizing the narrow linewidth output of the laser device.
Drawings
In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic top view of a hetero-integrated external cavity DBR semiconductor laser of the present utility model.
Fig. 2 is a schematic cross-sectional view of an F-P cavity semiconductor laser.
Fig. 3 is a schematic cross-sectional view of the AA' side of the PLC grating chip.
In the figure, 1, a laser chip; 11. an n-side electrode; 12. an InP substrate; 13. an InP buffer layer; 14. a lower waveguide layer; 15. a quantum well structure; 16. an upper waveguide layer; 17. SiO (SiO) 2 An insulating layer; 18. a strip-shaped current injection region; 19. a p-side electrode; 2. a PLC grating chip; 21. a substrate; 22. a lower cladding layer; 23. a waveguide grating; 24. an upper cladding layer; 3. a spot-size converter; 4. a straight waveguide; 5. a Bragg grating; 6. a lens; 7. tail fiber; 8. a light-emitting surface; 9. a non-light-emitting surface; 10. a coupling surface; 101. and an output end face.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without any inventive effort, are intended to be within the scope of the utility model.
Example 1
As shown in fig. 1 and 3, the heterogeneous integrated external cavity DBR semiconductor laser comprises a laser chip 1 and a PLC grating chip 2 which are coupled and connected, wherein the PLC grating chip 2 comprises a substrate 21, a lower cladding layer 22, a waveguide grating 23 and an upper cladding layer 24 are sequentially arranged on the substrate 21 from bottom to top, and the waveguide grating 23 consists of a mode spot converter 3, a straight waveguide 4 and a bragg grating 5 which are integrally integrated; the bragg grating 5 as the primary wavelength selective structure has a bragg wavelength that needs to be matched to the lasing wavelength of the laser chip 1. The bragg grating 5 is used as a main wavelength selective structure, and parameters of the bragg grating 5, such as grating period, grating duty cycle and the like, are determined according to actual process conditions. According to the prior reports, the high-order Bragg grating can be selected to increase the grating period, so that the preparation difficulty of the grating process is reduced. The light emergent surface 8 of the laser chip 1 is coupled with the end surface of the SSC spot converter 3, the SSC spot converter 3 enables the template emitted by the laser to be matched with the mode of the straight waveguide 4, and the coupling efficiency of the external cavity laser is improved.
Example 2
A heterogeneous integrated external cavity DBR semiconductor laser is shown in figure 1, the laser chip 1 is an F-P cavity laser, and the structure of the laser chip is a narrow F-P cavity with a ridge waveguide width of 3-5 mu m. The epitaxial structure of the laser chip 1 is a large optical cavity waveguide structure, and the slow axis divergence angle is increased by increasing the size of the waveguide structure, so that the fast axis divergence angle of the laser chip 1 is similar to the slow axis divergence angle. The lasing wavelength of the laser chip 1 is 1310nm, and the lasing wavelength of the laser chip 1 can also be 1550nm, so as to meet the wavelength band for communication.
Other structures are the same as in embodiment 1.
Example 3
As shown in fig. 1, a non-light-emitting surface 9 of the laser chip 1 is coated with a high-reflectivity film with a reflectivity of 95%, and a light-emitting surface 8 is coated with an antireflection film with a reflectivity of 0.001%, so that photons in the laser cavity are more easily emitted from the light-emitting surface 8. The light emergent surface 8 of the laser chip 1 is a coupling surface with the PLC grating chip 2, and the lower the reflectivity of the surface is, the more favorable the performance stability of the laser with the external cavity structure is.
The coupling surface 10 of the coupling connection end of the PLC grating chip 2 and the output end surface 101 of the other end of the coupling connection end of the laser chip 1 are plated with an antireflection film with the reflectivity of 0.001%. The antireflection film is prepared on the coupling surface 10 of the PLC grating chip 2, so that photons emitted by the laser can enter the PLC grating chip 2 more easily; an antireflection film is prepared on the output end face 101 of the PLC grating chip 2, namely the end face of the side where the Bragg grating 5 is located, so that photons are easier to emit.
Other structures are the same as in embodiment 2.
Example 4
As shown in fig. 1, the PLC grating chip 2 is connected with the pigtail 7, the pigtail 7 is directly connected to the output end face 101 of the bragg grating 5, and the laser output by the PLC grating chip 2 directly enters the non-fiber. In addition, a lens 6 can be arranged between the PLC grating chip 2 and the tail fiber 7, and the PLC grating chip 2 and the tail fiber 7 are coupled and connected through a lens group.
Other structures are as described in example 3.
The heterogeneous integrated external cavity DBR semiconductor laser is characterized in that light output by the semiconductor laser is subjected to wavelength selection through the SSC mode spot converter 3 and the straight waveguide 4, and as the length of the external cavity can be far longer than that of the semiconductor laser, the length of the external cavity is increased to prolong the service life of a photon carrier in the external cavity and effectively reduce the linewidth of the laser from the consideration of an equivalent external cavity narrow linewidth model. In addition, the wavelength can be narrowed by selecting the wavelength by the bragg grating 5 structure.
Example 5
A heterogeneous integrated external cavity DBR semiconductor laser, as shown in fig. 1-3, comprises a laser chip 1 and a PLC grating chip 2 coupled together. The laser chip 1 is an F-P cavity semiconductor laser, the cavity length of the F-P cavity semiconductor laser is 1mm, and the structure of the F-P cavity semiconductor laser sequentially comprises an n-face electrode 11 (Au/Ge/Ni material), an InP substrate 12, an InP buffer layer 13, a lower waveguide layer 14, a quantum well structure 15 (InGaAsP material), an upper waveguide layer 16 and SiO from bottom to top 2 An insulating layer 17, a strip current injection region 18, a p-side electrode 19 (Ti/Pt/Au material). The PLC grating chip 2 comprises a Si substrate 21, wherein SiO is sequentially arranged on the Si substrate 21 from bottom to top 2 Lower cladding layer 22, high refractive index SiO 2 Waveguide grating 23 and SiO 2 Upper bagThe layer 24, the waveguide grating 23 is composed of an integrally integrated mode spot-size converter 3, a straight waveguide 4 and a Bragg grating 5; the Bragg grating 5 period meets the Bragg condition, the grating duty ratio can be preferably 0.5, and the device process difficulty is reduced. The non-light-emitting surface 98 of the laser chip 1 is plated with a high-reflection film with the reflectivity of 95%, the light-emitting surface 8 is plated with an antireflection film with the reflectivity of 0.001%, and the PLC grating chip 2 is coupled with the tail fiber 7 through the lens 6 group.
The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.
Claims (10)
1. The heterogeneous integrated external cavity DBR semiconductor laser is characterized by comprising a laser chip (1) and a PLC grating chip (2) which are connected in a coupling way, wherein the PLC grating chip (2) comprises a substrate (21), a lower cladding layer (22), a waveguide grating (23) and an upper cladding layer (24) are sequentially arranged on the substrate (21) from bottom to top, and the waveguide grating (23) consists of a spot-size converter (3), a straight waveguide (4) and a Bragg grating (5) which are connected end to end; the light-emitting surface (8) of the laser chip (1) is coupled with the end surface of the spot-size converter (3).
2. The heterogeneous integrated external cavity DBR semiconductor laser of claim 1, wherein the waveguide grating (23) is SiO 2 A waveguide grating.
3. A hetero-integrated external cavity DBR semiconductor laser according to claim 1 or 2, characterized in that the laser chip (1) is an F-P cavity laser.
4. A hetero-integrated external cavity DBR semiconductor laser according to claim 3, characterized in that the lasing wavelength of the laser chip (1) is 1310nm or 1550nm.
5. The heterogeneous integrated external cavity DBR semiconductor laser of claim 4, wherein the non-light-emitting surface (9) of the laser chip (1) is coated with a highly reflective film and the light-emitting surface (8) of the laser chip (1) is coated with an anti-reflection film.
6. The heterogeneous integrated external cavity DBR semiconductor laser of claim 5, wherein the coupling surface (10) of the PLC grating chip (2) at the coupling connection end with the laser chip (1) and the output end surface (101) at the other end are both coated with an antireflection film.
7. The heterojunction integrated external cavity DBR semiconductor laser of claim 5 or 6, wherein the reflectivity of the anti-reflection film is not greater than 0.001%.
8. The heterojunction integrated external cavity DBR semiconductor laser of claim 5, wherein the reflectivity of the highly reflective film is not less than 95%.
9. The heterogeneous integrated external cavity DBR semiconductor laser of any of claims 1-2, 4-6 or 8, wherein the PLC grating chip (2) has a pigtail (7) attached thereto.
10. The heterogeneous integrated external cavity DBR semiconductor laser of claim 9, wherein a lens (6) is disposed between the PLC grating chip (2) and the pigtail (7), and the PLC grating chip (2) is coupled to the pigtail (7) through the lens (6).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320298516.3U CN219163905U (en) | 2023-02-23 | 2023-02-23 | Heterogeneous integrated external cavity DBR semiconductor laser |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320298516.3U CN219163905U (en) | 2023-02-23 | 2023-02-23 | Heterogeneous integrated external cavity DBR semiconductor laser |
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| CN219163905U true CN219163905U (en) | 2023-06-09 |
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| CN202320298516.3U Active CN219163905U (en) | 2023-02-23 | 2023-02-23 | Heterogeneous integrated external cavity DBR semiconductor laser |
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