Ring narrow linewidth laser and control method
By using a ring-shaped narrow linewidth laser structure and control method, the problems of immature laser packaging technology, high cost, high power consumption and high optical loss in existing lasers have been solved, achieving narrower laser linewidth, increased output power and simplified packaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHUYU TECH (HANGZHOU) CO LTD
- Filing Date
- 2024-08-30
- Publication Date
- 2026-06-05
AI Technical Summary
Existing methods for narrowing the linewidth of lasers suffer from problems such as immature packaging technology, high cost, high power consumption, and excessive optical loss, especially in the hybrid integration of semiconductor lasers and silicon-based external cavities.
A ring-shaped narrow linewidth laser structure is adopted. A ring optical path is formed by combining a semiconductor laser, a fiber Bragg grating, a beam splitter and a self-excited current regulator. The Fabry-Perot resonator between the fiber Bragg grating and the high-reflection film is used to achieve optical phase matching and frequency consistency, avoid additional phase shift function, reduce power consumption and reduce optical loss.
It achieves narrower laser linewidth, increased output power, and simpler packaging, reducing power consumption and optical loss, and is compatible with existing semiconductor laser packaging processes, making it easy to manufacture.
Smart Images
Figure CN119297730B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of laser technology, and in particular to a ring-shaped narrow linewidth laser and its control method. Background Technology
[0002] With the development of coherent optical communication, lidar, wind-measuring radar, medical photonics, and long-range sensing, the linewidth requirements for lasers are becoming increasingly narrow. Currently, the mainstream method for achieving linewidth narrowing is the hybrid integration of semiconductor lasers with silicon-based external cavities. This primarily utilizes high-quality factor external cavities, such as silicon-based microrings and silicon-based Bragg gratings. These methods can achieve excellent linewidth narrowing, even reaching the Hz level. However, their drawbacks are also significant, such as:
[0003] 1) The hybrid integrated packaging technology of silicon-based external cavity and semiconductor laser is not yet mature and the packaging cost is high;
[0004] 2) Its power consumption is too high due to the addition of extra phase shift functionality;
[0005] 3) Excessive light loss during hybrid integration generally results in low output power of hybrid integrated lasers.
[0006] Based on the shortcomings of the above technologies, we propose a ring-shaped narrow linewidth laser and its control method. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a ring-shaped narrow linewidth laser and a control method thereon.
[0008] To achieve the above objectives, the present invention adopts the following technical solution:
[0009] A ring-shaped narrow linewidth laser includes a semiconductor laser, a fiber Bragg grating, a beam splitter, an output port, and a self-excited current regulator.
[0010] The semiconductor laser has a first coupling end, a second coupling end, and an internal resonant cavity. The first coupling end is coated with an anti-reflection film, and the second coupling end is coated with a high-reflection film.
[0011] The beam splitter includes a low-ratio output terminal and a high-ratio output terminal, and the high-ratio output terminal is coupled to the light output port.
[0012] The first coupling end, the fiber Bragg grating, the low-ratio output end, and the second coupling end are coupled sequentially to form a ring optical path;
[0013] The fiber Bragg grating is used to reflect the clockwise light output from the first coupling end and also to reflect the counterclockwise light output from the second coupling end.
[0014] A first Fabry-Perot resonant cavity is formed between one end of the fiber Bragg grating and the high-reflectivity film; a second Fabry-Perot resonant cavity is formed between the other end of the fiber Bragg grating and the high-reflectivity film, wherein the first Fabry-Perot resonant cavity and the second Fabry-Perot resonant cavity have different cavity lengths.
[0015] The self-excited current regulator is used to tune the current injected into the semiconductor laser so that the oscillation frequency of the semiconductor laser, the oscillation frequency of the first Fabry-Perot resonator, and the oscillation frequency of the second Fabry-Perot resonator are consistent, thereby achieving linewidth narrowing.
[0016] Preferably, it further includes a first optical fiber and a second optical fiber; one end of the first optical fiber is coupled to the first coupling end, and the other end is coupled to one end of the second optical fiber through the low-ratio output end, and the other end of the second optical fiber is coupled to the second coupling end.
[0017] Preferably, the first optical fiber is coupled to the semiconductor laser via a lens; and / or, the second optical fiber is coupled to the semiconductor laser via a lens.
[0018] Preferably, the first optical fiber is configured as a lens fiber or a diced fiber, and / or the second optical fiber is configured as a lens fiber or a diced fiber.
[0019] Preferably, the antireflective coating has a reflectivity of less than 1%; the high reflectivity coating has a reflectivity of greater than 90%.
[0020] Preferably, the splitting ratio between the low-ratio output terminal and the high-ratio output terminal is selected from any one of 5% / 95%, 10% / 90%, and 20% / 80%.
[0021] A control method for a ring-shaped narrow-linewidth laser, as described above, is disclosed. The ring-shaped narrow-linewidth laser includes a semiconductor laser, a fiber Bragg grating, a beam splitter, an output port, and a self-excited current regulator. The semiconductor laser has a first coupling end, a second coupling end, and an internal resonant cavity. The first coupling end is coated with an anti-reflection film, and the second coupling end is coated with a high-reflection film. A first Fabry-Perot resonant cavity is formed between the fiber Bragg grating and the high-reflection film; a second Fabry-Perot resonant cavity is formed between the fiber Bragg grating and the high-reflection film. The first and second Fabry-Perot resonant cavities have different cavity lengths. The control method includes the following steps: injecting a preset current into the semiconductor laser to output a preset output light; tuning the preset current injected into the semiconductor laser to make the oscillation frequency of the semiconductor laser, the oscillation frequency of the first and second Fabry-Perot resonant cavities consistent, thereby achieving linewidth narrowing; and outputting narrow-linewidth laser light through the output port.
[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0023] The aforementioned technical solution provides a ring-shaped narrow-linewidth laser. A first coupling end, a fiber Bragg grating, a low-ratio output end, and a second coupling end are sequentially coupled to form a ring optical path. This ensures that the phase of the light remains matched throughout the narrow-linewidth laser, eliminating the need for additional phase-shifting functions and reducing overall laser power consumption. Furthermore, the optical loss of optical fiber is five orders of magnitude lower than that of silicon-based materials, and the mature coupling technology between semiconductor lasers and optical fibers avoids excessive light loss during hybrid integration, thereby increasing the laser's output power. Moreover, compared to existing silicon-based micro-ring and silicon-based Bragg grating lasers, this solution eliminates the need for a phase-shifting structure, resulting in a simpler overall structure that is compatible with existing semiconductor laser packaging processes, facilitating laser packaging. Simultaneously, a first Fabry-Perot resonant cavity is formed between the fiber Bragg grating and the high-reflectivity film; a second Fabry-Perot resonant cavity is formed between the fiber Bragg grating and the high-reflectivity film. The different lengths of the first and second Fabry-Perot resonant cavities result in different FP mode intervals, generating an optical vernier effect. By tuning the current injected into the semiconductor laser through a self-excited current regulator, the oscillation frequency of the semiconductor laser's internal resonant cavity is made to match the oscillation frequencies of the first and second Fabry-Perot cavities formed in the ring optical path, thus achieving linewidth narrowing. Correspondingly, the control method for the aforementioned ring-shaped narrow-linewidth laser has the advantages of narrowing the linewidth, increasing output power, and simple packaging. Attached Figure Description
[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0025] Figure 1 This is a schematic diagram of the narrow linewidth laser provided by the present invention.
[0026] Figure 2 This is a schematic diagram of the optical vernier effect.
[0027] Figure 3 This is a linewidth test diagram from one embodiment.
[0028] Explanation of reference numerals in the attached figures:
[0029] 1. Semiconductor laser; 11. First coupling end; 12. Second coupling end; 2. Fiber Bragg grating; 3. Beam splitter; 31. Low ratio output end; 32. High ratio output end; 4. Light output port; 5. First optical fiber; 6. Second optical fiber. Detailed Implementation
[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0033] See Figures 1 to 3 This invention provides a ring-shaped narrow linewidth laser, comprising a semiconductor laser 1, a fiber Bragg grating 2, a beam splitter 3, an output port 4, and a self-excited current regulator.
[0034] Specifically, the semiconductor laser 1 has a first coupling end 11, a second coupling end 12, and an internal resonant cavity. The first coupling end 11 is coated with an anti-reflection film, and the second coupling end 12 is coated with a high-reflection film. The beam splitter 3 includes a low-ratio output end 31 and a high-ratio output end 32, with the high-ratio output end 32 coupled to the output port 4. The first coupling end 11, the fiber Bragg grating 2, the low-ratio output end 31, and the second coupling end 12 are coupled sequentially to form a ring optical path. The fiber Bragg grating 2 is used to reflect the forward light output from the first coupling end 11 and also to reflect the light from the second coupling end 12. 12. Reverse time of coupled output; a first Fabry-Perot resonant cavity is formed between one end of the fiber Bragg grating 2 and the high-reflection film; a second Fabry-Perot resonant cavity is formed between the other end of the fiber Bragg grating 2 and the high-reflection film, the first Fabry-Perot resonant cavity and the second Fabry-Perot resonant cavity have different cavity lengths; a self-excited current regulator is used to tune the current injected into the semiconductor laser 1 so that the oscillation frequency of the semiconductor laser 1, the oscillation frequency of the first Fabry-Perot resonant cavity and the oscillation frequency of the second Fabry-Perot resonant cavity are consistent, thereby achieving linewidth narrowing.
[0035] In this embodiment, the first coupling end 11, the fiber Bragg grating 2, the low-ratio output end 31, and the second coupling end 12 are sequentially coupled and connected to form a ring optical path. This ensures that the phase of the light remains matched in the narrow-linewidth laser, eliminating the need for additional phase-shifting functions and reducing the overall power consumption of the laser. Furthermore, the optical loss of optical fiber is five orders of magnitude lower than that of silicon-based materials, and the mature coupling technology between semiconductor lasers and optical fibers avoids excessive light loss during hybrid integration, thereby increasing the output power of the laser. In addition, compared to existing silicon-based micro-ring and silicon-based Bragg grating lasers, this solution does not require a phase-shifting structure, has a simple overall structure, is compatible with existing semiconductor laser packaging technology, and facilitates laser packaging. Simultaneously, a first Fabry-Perot resonant cavity is formed between the fiber Bragg grating 2 and the high-reflectivity film; a second Fabry-Perot resonant cavity is formed between the fiber Bragg grating 2 and the high-reflectivity film. This allows the lengths of the first and second Fabry-Perot resonant cavities to be different, resulting in different FP mode intervals and generating an optical vernier effect. By tuning the current injected into the semiconductor laser 1 through the self-excited current regulator, when the oscillation frequency of the inner resonant cavity of the semiconductor laser 1 matches the oscillation frequencies of the first and second Fabry-Perot cavities formed in the ring optical path, linewidth narrowing can be achieved.
[0036] See Figure 1 In this embodiment, the ring-shaped narrow linewidth laser also includes a first optical fiber 5 and a second optical fiber 6. One end of the first optical fiber 5 is coupled to a first coupling end 11, and the other end is coupled to one end of the second optical fiber 6 through a low-ratio output end 31. The other end of the second optical fiber 6 is coupled to a second coupling end 12. The maturity of semiconductor laser and fiber coupling technology can avoid excessive light loss during hybrid integration, thereby increasing the output power of the laser.
[0037] Specifically, the first optical fiber 5 is coupled to the semiconductor laser 1 through a lens, and the second optical fiber 6 is coupled to the semiconductor laser 1 through a lens.
[0038] To elaborate further, the fiber Bragg grating 2 is fabricated on the first fiber 5.
[0039] Furthermore, the first optical fiber 5 can be a lens fiber or a cleaved fiber, and the second optical fiber 6 can also be a lens fiber or a cleaved fiber.
[0040] In this embodiment, the reflectivity of the antireflective coating is less than 1%; the reflectivity of the high reflectivity coating is greater than 90%.
[0041] In this embodiment, the splitting ratio of the low-ratio output terminal 31 and the high-ratio output terminal 32 can be set to 5% / 95%, 10% / 90%, or 20% / 80%.
[0042] As described above, when this narrow-linewidth laser is in use, a certain value of current is injected into the semiconductor laser 1, causing the semiconductor laser 1 to emit light of a certain frequency. A portion of the light emitted by the semiconductor laser 1 is coupled into the first optical fiber 5. For ease of description, this portion of light is called forward-looking light. The forward-looking light passes through the fiber Bragg grating 2, with a small portion reflected back into the semiconductor laser 1 by the fiber Bragg grating 2, and the majority transmitted through the fiber Bragg grating 2 to the beam splitter 3. Most of the forward-looking light transmitted to the beam splitter 3 is output through the high-ratio output end 32 and the output port 4. A portion of the light emitted by the semiconductor laser 1 is coupled into the second optical fiber 6. For ease of description, this portion of light is called reverse-looking light. A portion of the reverse-looking light passes through the beam splitter 3 and is then reflected back into the semiconductor laser 1 by the fiber Bragg grating 2.
[0043] It can be seen that at this point, the semiconductor laser 1, the first optical fiber 5, the beam splitter 3, and the second optical fiber 6 form a ring optical path. (See also...) Figure 1 and Figure 2 In the clockwise direction, the high-reflectivity film of the semiconductor laser 1 and the fiber Bragg grating 2 form a first Fabry-Perot resonator; in the counterclockwise direction, the high-reflectivity film of the semiconductor laser 1 and the fiber Bragg grating 2 form a second Fabry-Perot resonator. Since the lengths of the inner resonator of the semiconductor laser 1, the first Fabry-Perot resonator, and the second Fabry-Perot resonator are different, the FP mode spacing Δλ2 of the first Fabry-Perot resonator and the λ3 of the second Fabry-Perot resonator will also be different for λ1, thus producing an optical vernier effect. By tuning the current injected into the semiconductor laser 1, λ1, the oscillation frequency λ2 of the first Fabry-Perot resonator, and the oscillation frequency λ3 of the second Fabry-Perot resonator are kept consistent, linewidth narrowing can be achieved.
[0044] Further, see Figure 3 , Figure 3 The linewidth test diagram shows that the integrated linewidth of about 7kHz was measured using the delayed self-heterodyne method, and the output power was about 15dBm.
[0045] This application also provides a control method based on the above-mentioned ring-shaped narrow linewidth laser, which specifically includes the following steps:
[0046] A preset current is injected into semiconductor laser 1 to make semiconductor laser 1 output a preset output light;
[0047] The preset current injected into the semiconductor laser 1 is tuned to make the oscillation frequency of the semiconductor laser 1, the oscillation frequency of the first Fabry-Perot resonator, and the oscillation frequency of the second Fabry-Perot resonator consistent, thereby achieving linewidth narrowing.
[0048] Narrow linewidth laser is output through output port 4.
[0049] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A ring-shaped narrow linewidth laser, characterized in that, It includes a semiconductor laser (1), a fiber Bragg grating (2), a beam splitter (3), an output port (4), and a self-excited current regulator; The semiconductor laser (1) has a first coupling end (11), a second coupling end (12) and an internal resonant cavity. The first coupling end (11) is coated with an anti-reflection film, and the second coupling end (12) is coated with a high-reflection film. The beam splitter (3) includes a low-ratio output terminal (31) and a high-ratio output terminal (32), and the high-ratio output terminal (32) is coupled to the light output port (4); The first coupling end (11), the fiber Bragg grating (2), the low-ratio output end (31), and the second coupling end (12) are coupled in sequence to form a ring optical path; The fiber Bragg grating (2) is used to reflect the clockwise light output from the first coupling end (11) and also to reflect the counterclockwise light output from the second coupling end (12); One end of the fiber Bragg grating (2) forms a first Fabry-Perot resonant cavity with the high-reflectivity film to resonate with the light in the clockwise direction, and the other end forms a second Fabry-Perot resonant cavity with the high-reflectivity film to resonate with the light in the counterclockwise direction. The first Fabry-Perot resonant cavity and the second Fabry-Perot resonant cavity have different cavity lengths. The self-excited current regulator is used to tune the current injected into the semiconductor laser (1) so that the oscillation frequency of the semiconductor laser (1), the oscillation frequency of the first Fabry-Perot resonator and the oscillation frequency of the second Fabry-Perot resonator are consistent, thereby achieving linewidth narrowing.
2. The annular narrow linewidth laser according to claim 1, characterized in that, It also includes a first optical fiber (5) and a second optical fiber (6); One end of the first optical fiber (5) is coupled to the first coupling end (11), and the other end is coupled to one end of the second optical fiber (6) through the low ratio output end (31). The other end of the second optical fiber (6) is coupled to the second coupling end (12).
3. A ring-shaped narrow linewidth laser according to claim 2, characterized in that, The fiber Bragg grating (2) is fabricated on the first optical fiber (5).
4. A ring-shaped narrow linewidth laser according to claim 2, characterized in that, The first optical fiber (5) is coupled to the semiconductor laser (1) through a lens; And / or, The second optical fiber (6) is coupled to the semiconductor laser (1) through a lens.
5. A ring-shaped narrow linewidth laser according to claim 2, characterized in that, The first optical fiber (5) is configured as a lens fiber or a cleaved fiber. And / or, The second optical fiber (6) is configured as a lens fiber or a cut fiber.
6. A ring-shaped narrow linewidth laser according to any one of claims 1 to 5, characterized in that, The reflectivity of the antireflective film is less than 1%; The high-reflectivity film has a reflectivity greater than 90%.
7. A ring-shaped narrow linewidth laser according to any one of claims 1 to 5, characterized in that, The splitting ratio of the low-ratio output terminal (31) and the high-ratio output terminal (32) can be selected from any one of 5% / 95%, 10% / 90%, and 20% / 80%.
8. A control method for a ring-shaped narrow linewidth laser based on any one of claims 1 to 7, characterized in that, The ring-shaped narrow linewidth laser includes a semiconductor laser (1), a fiber Bragg grating (2), a beam splitter (3), an output port (4), and a self-excited current regulator. The semiconductor laser (1) has a first coupling end (11), a second coupling end (12), and an internal resonant cavity. The first coupling end (11) is coated with an anti-reflection film, and the second coupling end (12) is coated with a high-reflection film. A first Fabry-Perot resonant cavity is formed between the fiber Bragg grating (2) and the high-reflection film. A second Fabry-Perot resonant cavity is formed between the fiber Bragg grating (2) and the high-reflection film. The first Fabry-Perot resonant cavity and the second Fabry-Perot resonant cavity have different cavity lengths. The control method includes the following steps: A preset current is injected into the semiconductor laser (1) to make the semiconductor laser (1) output a preset output light; A preset current is tuned and injected into the semiconductor laser (1) so that the oscillation frequency of the semiconductor laser (1), the oscillation frequency of the first Fabry-Perot resonator and the oscillation frequency of the second Fabry-Perot resonator are consistent, thereby achieving linewidth narrowing; Narrow linewidth laser is output through the light output port (4).