Laser based on annular resonant cavity and grating fiber coupling

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on annular resonant cavity and grating fiber coupling. The annular optical gain ring optical waveguide is arranged on the upper end face of the substrate; the top positive electrode is plated on the upper end surface of the optical waveguide of the annular optical gain ring; the bottom negative electrode is plated on the lower end surface of the substrate; the Bragg grating optical fiber is arranged on the upper end face of the substrate 1, and the Bragg grating optical fiber wraps part of the annular optical gain ring optical waveguide from the outside; the HR high-reflection film is plated on the end face, deviating from the light output direction, of the Bragg grating optical fiber; and the AR film is plated on the end face of the Bragg grating fiber in the light output direction. The method has the following beneficial effects: 1, the process is simplified, and the cost is reduced; 2, the coupling loss is extremely low; 3, the line width is narrow and the monochromaticity is high; and 4, the structural stability is high.

Description

A laser based on a ring resonant cavity and grating fiber coupling Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically to a laser based on a ring resonant cavity and grating fiber coupling. Background Technology

[0002] Semiconductor lasers, as core components of optoelectronic technology, are widely used in communications, sensing, and medical fields. Currently, the industry faces the following limitations:

[0003] 1. Most lasers use a linear waveguide structure, and the resonant cavity is an open linear structure. High-precision cutting, polishing and coating (such as high-reflection HR film and anti-reflection AR film) are required on both ends, which is complex and costly.

[0004] 2. The coupling between the linear waveguide chip and the external optical fiber requires high-precision alignment, which inevitably results in more than 30% optical power loss, reducing the device efficiency.

[0005] 3. The limited length of the linear resonant cavity results in a relatively wide laser linewidth, which makes it difficult to meet the requirements of high-precision applications for narrow linewidth and high monochromaticity.

[0006] Therefore, there is an urgent need for a new laser structure that can simplify the process, reduce coupling loss, and improve the quality of output light. Summary of the Invention

[0007] The purpose of this invention is to solve the problems mentioned in the background section. This invention provides the following technical solution: a laser based on a ring resonant cavity and grating fiber coupling, comprising:

[0008] Substrate;

[0009] A ring-shaped optical gain ring waveguide is disposed on the upper end face of the substrate;

[0010] The top positive electrode is plated on the upper end face of the annular optical gain ring waveguide;

[0011] The bottom negative electrode is plated on the lower end face of the substrate;

[0012] A Bragg grating fiber is disposed on the upper end face of the substrate 1, and the Bragg grating fiber wraps around part of the annular optical gain ring waveguide from the outside;

[0013] HR high reflectivity film is deposited on the end face of the Bragg grating fiber away from the light output direction;

[0014] An AR anti-reflective film is deposited on the end face of the Bragg grating fiber in the direction of light output.

[0015] As a preferred embodiment of the above technical solution, the emission wavelength of the ring-shaped optical gain ring waveguide is 1550nm.

[0016] As a preferred embodiment of the above technical solution, the substrate is an n⁻ type InP-based material.

[0017] As a preferred embodiment of the above technical solution, the annular optical gain ring waveguide has an annular diameter of 1000μm, a width of 2μm, and a depth of 0.8μm.

[0018] As a preferred embodiment of the above technical solution, the top positive electrode is a Ti / Au metal electrode layer with a thickness of 200nm.

[0019] As a preferred embodiment of the above technical solution, the Bragg grating fiber is a single-mode fiber with a grating period of 0.53 μm and a length of 10 mm.

[0020] As a preferred embodiment of the above technical solution, the coupling distance between the Bragg grating fiber and the ring optical gain ring waveguide 2 is 10 μm.

[0021] As a preferred embodiment of the above technical solution, the HR high-reflectivity film is made of Al2O3 material with a reflectivity > 95%.

[0022] This invention provides a laser based on a ring resonant cavity and grating fiber coupling, which has the following advantages:

[0023] 1. Simplified process and reduced cost: The ring-shaped optical waveguide adopts a self-circulating closed-loop structure, eliminating the need for end face cutting, polishing and coating, saving the difficult end face processing steps in traditional processes, and significantly reducing process complexity and production costs.

[0024] 2. Extremely low coupling loss: The Bragg grating fiber is coupled to the ring optical gain ring waveguide at a close distance of 10μm, avoiding the power loss of more than 30% in traditional fiber alignment coupling and improving optical power utilization.

[0025] 3. Narrow linewidth and high monochromaticity: The length of the ring resonator is more than 4 times that of a linear structure of the same size. Combined with the mode selection filtering effect of the Bragg grating fiber, the linewidth is narrowed twice, and the output light quality is significantly improved.

[0026] 4. High structural stability: The ring-shaped closed-loop structure and close-range coupling method reduce the interference of the external environment on the resonant cavity, resulting in stronger device stability. Attached Figure Description

[0027] Figure 1 is a top view of the present invention, used to show the positional relationship between the ring optical gain ring waveguide and the Bragg grating fiber in the present invention.

[0028] Figure 2 is a front view of the present invention, used to show the positional relationship between the annular optical gain ring waveguide and the top positive electrode in the present invention.

[0029] In the figure: 1. Substrate; 2. Ring-shaped gain ring waveguide; 3. Top positive electrode; 4. Bottom negative electrode; 5. Bragg grating fiber; 6. HR high reflectivity film; 7. AR antireflection film. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] A laser based on a ring resonant cavity and grating fiber coupling, comprising:

[0032] Substrate 1;

[0033] An annular optical gain ring waveguide 2 is disposed on the upper end face of the substrate 1;

[0034] The top positive electrode 3 is plated on the upper end face of the annular optical gain ring waveguide 2;

[0035] The bottom negative electrode 4 is plated on the lower end surface of the substrate 1;

[0036] A Bragg grating fiber 5 is disposed on the upper end surface of the substrate 1, and the Bragg grating fiber 5 wraps around part of the annular optical gain ring waveguide 2 from the outside;

[0037] The HR high-reflectivity film 6 is deposited on the end face of the Bragg grating fiber 5 away from the light output direction.

[0038] AR anti-reflective film 7 is deposited on the end face of the Bragg grating optical fiber 5 in the light output direction.

[0039] As a preferred embodiment of the above technical solution, the emission wavelength of the annular optical gain ring waveguide 2 is 1550nm.

[0040] As a preferred embodiment of the above technical solution, the substrate 1 is an n⁻ type InP-based material.

[0041] As a preferred embodiment of the above technical solution, the annular optical gain ring waveguide 2 has an annular diameter of 1000μm, a width of 2μm, and a depth of 0.8μm.

[0042] As a preferred embodiment of the above technical solution, the top positive electrode 3 is a Ti / Au metal electrode layer with a thickness of 200nm.

[0043] As a preferred embodiment of the above technical solution, the Bragg grating fiber 5 is a single-mode fiber with a grating period of 0.53 μm and a length of 10 mm.

[0044] As a preferred embodiment of the above technical solution, the coupling distance between the Bragg grating fiber 5 and the ring optical gain ring waveguide 2 is 10 μm.

[0045] As a preferred embodiment of the above technical solution, the HR high-reflectivity film 6 is made of Al2O3 material with a reflectivity > 95%.

[0046] The working principle of this invention is as follows:

[0047] When a positive driving current is applied between the top positive electrode 3 and the bottom negative electrode 4, the spine waveguide of the annular optical gain ring waveguide 2 generates stimulated emission under current excitation, forming a laser that circulates within the annular resonant cavity. Due to the close proximity of the Bragg grating fiber 5 to the annular optical gain ring waveguide 2, some of the laser light is coupled into the Bragg grating fiber via evanescent wave coupling. The Bragg grating fiber 5 filters the optical signal through the grating structure, allowing only the optical signal that meets the half-wavelength reflection condition (i.e., the wavelength matching the grating period) to be reflected. After being enhanced by the HR high-reflectivity film 6, the light is fed back to the spine waveguide of the annular optical gain ring waveguide 2 through close-range coupling. The feedback optical signal is superimposed on the laser light in the annular cavity, further enhancing the optical signal of a specific wavelength. At the same time, by utilizing the dual effects of the annular long cavity (the length of the annular resonant cavity is more than 4 times that of the linear structure for the same chip length) and grating mode selection, the laser linewidth is significantly narrowed, and finally, a high-quality laser light is output through the other end of the Bragg grating fiber 5.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A laser based on a ring resonant cavity and grating fiber coupling, characterized in that: include: Substrate (1); Ring-shaped optical waveguide (2), disposed on the upper end face of the substrate (1); A top positive electrode (3) is deposited on the upper end face of the annular optical gain ring waveguide (2); a bottom negative electrode (4) is deposited on the lower end face of the substrate (1); a Bragg grating fiber (5) is disposed on the upper end face of the substrate (1), and the Bragg grating fiber (5) wraps around part of the annular optical gain ring waveguide (2) from the outside; an HR high reflectivity film (6) is deposited on the end face of the Bragg grating fiber (5) away from the light output direction; and an AR antireflectivity film (7) is deposited on the end face of the Bragg grating fiber (5) in the light output direction.

2. A laser based on a ring resonant cavity and grating fiber coupling according to claim 1, characterized in that: The emission wavelength of the ring-shaped optical gain ring waveguide (2) is 1550nm.

3. A laser based on a ring resonant cavity and grating fiber coupling according to claim 1, characterized in that: The substrate (1) is an n⁻ type InP-based material.

4. A laser based on a ring resonant cavity and grating fiber coupling according to claim 2, characterized in that: The annular optical gain ring waveguide (2) has an annular diameter of 1000μm, a width of 2μm, and a depth of 0.8μm.

5. A laser based on a ring resonant cavity and grating fiber coupling according to claim 4, characterized in that: The top positive electrode (3) is a Ti / Au metal electrode layer with a thickness of 200nm.

6. A laser based on a ring resonant cavity and grating fiber coupling according to claim 5, characterized in that: The Bragg grating fiber (5) is a single-mode fiber with a grating period of 0.53 μm and a length of 10 mm.

7. A laser based on a ring resonant cavity and grating fiber coupling according to claim 6, characterized in that: The coupling distance between the Bragg grating fiber (5) and the ring optical gain ring waveguide 2 is 10 μm.

8. A laser based on a ring resonant cavity and grating fiber coupling according to claim 7, characterized in that: The HR high-reflectivity film (6) is made of Al2O3 material with a reflectivity >95%.

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