Stimulated Brillouin laser based on SMS structure and acousto-optic Q switch

Abstract

The utility model provides a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q switch, which comprises the SMS structure, a third single-mode fiber, a fiber combiner, a gain fiber, the acousto-optic Q switch and a fiber bragg grating which are connected in sequence, and further comprises at least one pumping source connected with the fiber combiner. The SMS structure comprises a first single-mode optical fiber, a multimode optical fiber and a second single-mode optical fiber which are connected in sequence, and the second single-mode optical fiber is connected with a third single-mode optical fiber. According to the stimulated Brillouin laser based on the SMS structure and the acousto-optic Q switch provided by the utility model, the technical problem that the output repetition frequency and pulse width of a self-adjusting Q Brillouin laser are unstable is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lasers, and in particular relates to a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q switch. Background Art

[0002] Stimulated Brillouin scattering (SBS) is an effective way to obtain high-power Q-switched pulsed lasers. However, similar to other Q-switching techniques, it also exhibits problems of unstable pulse width and repetition rate. Theoretical and experimental results show that thermal noise generated during Brillouin scattering is the active cause of SBS pulse period and intensity fluctuations. Summary of the invention

[0003] The utility model provides a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q switch, which solves the technical problem of unstable output repetition frequency and pulse width of a self-Q-switched Brillouin laser.

[0004] In order to solve the above technical problems, an embodiment of the utility model provides a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q-switch, comprising an SMS structure, a third single-mode optical fiber, a fiber combiner, a gain fiber, an acousto-optic Q-switch and a fiber Bragg grating connected in sequence, and also comprising at least one pump source, which is connected to the fiber combiner; the SMS structure comprises a first single-mode optical fiber, a multimode optical fiber and a second single-mode optical fiber connected in sequence, and the second single-mode optical fiber is connected to the third single-mode optical fiber.

[0005] As a further improvement of the embodiment of the utility model, the length of the multimode optical fiber is 1 mm to 10 cm.

[0006] As a further improvement of an embodiment of the utility model, the length of the third single-mode optical fiber is greater than or equal to 1 m.

[0007] As a further improvement of an embodiment of the utility model, the gain fiber is a fiber doped with rare earth elements, and the doping element is one or more of ytterbium, thulium, holmium, bismuth, samarium, erbium, and chromium.

[0008] As a further improvement of the embodiment of the utility model, the end of the first single-mode optical fiber that is not connected to the multi-mode optical fiber has a bevel angle, and the angle of the bevel angle is 8°.

[0009] As a further improvement of the embodiment of the utility model, the end of the fiber Bragg grating not connected to the acousto-optic Q switch has a bevel angle, and the angle of the bevel angle is 8°.

[0010] Compared with the prior art, the technical solution of the utility model has the following beneficial effects:

[0011] The utility model provides a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q switch. The SMS structure is used to filter and manage feedback on one side of the stimulated Brillouin laser, and the acousto-optic Q switch manages feedback on the other side of the stimulated Brillouin laser and controls the repetition frequency at the same time. After the acousto-optic Q switch is turned on, oscillation occurs in the resonant cavity composed of the SMS structure, the third single-mode optical fiber, the optical fiber combiner, the gain optical fiber, the acousto-optic Q switch and the optical fiber grating to generate SBS self-Q-switched pulses. The SMS structure is composed of a multimode optical fiber and single-mode optical fibers on both sides. When the length of the multimode optical fiber is fixed, only one wavelength of light can be self-focused at the output position and output at the maximum energy value. When the light of the remaining wavelengths is transmitted in the multimode optical fiber, the output coupling ratio is very low and the loss is extremely large. Thereby, it is possible to actively apply specific feedback to each order of Stokes light, cover up the random feedback of thermal noise and Rayleigh scattering, and effectively suppress the wavelength random output characteristics of the SBS self-Q-switched laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of a stimulated Brillouin laser based on an SMS structure and an acousto-optic Q switch according to an embodiment of the utility model;

[0013] Figure 2 yes Figure 1 Structural diagram of the SMS structure.

[0014] The figure includes: SMS structure 1, a first single-mode optical fiber 11, a multi-mode optical fiber 12, a second single-mode optical fiber 13, a third single-mode optical fiber 2, an optical fiber combiner 3, a gain optical fiber 5, an acousto-optic Q switch 6, and a fiber Bragg grating 7. DETAILED DESCRIPTION

[0015] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings.

[0016] The utility model embodiment provides a stimulated Brillouin laser based on SMS structure and acousto-optic Q switch, such as Figure 1 As shown, it includes an SMS structure 1, a third single-mode optical fiber 2, a fiber combiner 3, at least one pump source 4, a gain optical fiber 5, an acousto-optic Q switch 6 and a fiber grating 7. Figure 2As shown, the SMS structure 1 includes a first single-mode optical fiber 11, a multi-mode optical fiber 12, and a second single-mode optical fiber 13. One end of the first single-mode optical fiber 11 is connected to one end of the multi-mode optical fiber 12, and the other end of the multi-mode optical fiber 12 is connected to one end of the second single-mode optical fiber 13. The other end of the second single-mode optical fiber 13 is connected to one end of the third single-mode optical fiber 2. The other end of the third single-mode optical fiber 2 is connected to the input end of the fiber combiner 3, and the pump source 4 is connected to the fiber combiner 3. The input end of the fiber combiner 3 is connected to one end of the gain optical fiber 5, and the other end of the gain optical fiber 5 is connected to one end of the acousto-optic Q switch 6 through a single-mode optical fiber, and the other end of the acousto-optic Q switch 6 is connected to the fiber Bragg grating 7 through a single-mode optical fiber.

[0017] Among them, there are N pump sources 4 for providing pump light. N is an integer greater than 1. For example, N=1, 2, 3, 4 or 5. The fiber combiner 3 is an (N+1)×1 type fiber combiner, which is used to input the pump light into the gain fiber 5. The gain fiber 5 is used to absorb the pump light and generate gain. The third single-mode fiber 2 is used to lower the stimulated Brillouin scattering threshold, trigger stimulated Brillouin scattering, and generate multi-order Stokes light. The SMS structure 1 is used to filter and manage the feedback of the Stokes light on the left side of the stimulated Brillouin laser. The fiber grating 7 is used to generate feedback on the right side of the stimulated Brillouin laser. The acousto-optic Q switch 6 is used to control the right-side feedback and repetition frequency when it is turned on.

[0018] The stimulated Brillouin laser of this embodiment adopts an SMS structure for filtering and managing feedback on one side of the stimulated Brillouin laser, and an acousto-optic Q switch manages feedback on the other side of the stimulated Brillouin laser and controls the repetition frequency at the same time. When the acousto-optic Q switch is turned on, oscillation occurs to generate SBS self-switched Q pulses. The SMS structure is composed of a multimode optical fiber and single-mode optical fibers on both sides. When the length of the multimode optical fiber is fixed, only one wavelength of light can be self-focused at the output position and output at the maximum energy value. When the light of the remaining wavelengths is transmitted in the multimode optical fiber, the output coupling ratio is very low and the loss is extremely large. In this way, it is possible to actively apply specific feedback to each order of Stokes light, mask the random feedback of thermal noise and Rayleigh scattering, and the random output characteristics of the wavelength of the SBS self-switched Q laser can be effectively suppressed.

[0019] Preferably, the length of the multimode optical fiber 12 is 1 mm to 10 cm. By adjusting the length of the multimode optical fiber 12, the wavelength band that can pass can be controlled.

[0020] Preferably, the length of the third single-mode optical fiber 2 is greater than or equal to 1m. The length of the third single-mode optical fiber affects the Brillouin scattering threshold, and the longer the optical fiber, the lower the threshold. In this embodiment, the length of the third single-mode optical fiber is set to be greater than or equal to 1m, which can ensure that SBS can be triggered.

[0021] Preferably, the gain fiber 5 is a fiber doped with rare earth elements, and the doping element is one or more of ytterbium, thulium, holmium, bismuth, samarium, erbium, and chromium.

[0022] Preferably, the other end of the first single-mode optical fiber 11 (the end not connected to the multimode optical fiber 12) and the other end of the fiber grating 7 (the end not connected to the acousto-optic Q switch 6) both have a bevel angle, and the angle of the bevel angle is 8°. The end faces of both ends of the laser are set with a bevel angle to prevent the end faces from providing feedback and ensure that the feedback on the left and right sides is provided by Rayleigh scattering in the optical fiber.

[0023] A specific example is provided below.

[0024] The multimode optical fiber 12 uses a 20μm / 125μm, 5cm long passive optical fiber. The third single-mode optical fiber uses a 6μm / 125μm passive optical fiber. The optical fiber combiner uses a 10μm / 125μm (1+1)×1 pump combiner. The pump source uses a 10W semiconductor laser with a locked central wavelength of 976nm. The gain fiber uses an ytterbium-doped optical fiber with a fiber size of 10μm / 125μm produced by Nufern, USA. Both sides of the acousto-optic Q switch use 6μm / 125μm single-mode optical fibers.

[0025] The pump light generated by the pump source is coupled into the gain fiber through the (1+1)×1 signal pump combiner, and the gain fiber absorbs the pump light to accumulate the inverted population. At this time, the acousto-optic Q switch on the right is in the off state, and no feedback is generated on the right. The SMS structure on the left only allows the laser in the high-order Stokes band to pass through. After the acousto-optic Q switch is turned on, the right side gives feedback through the fiber Bragg grating, so that the light in the resonant cavity composed of the SMS structure, the third single-mode fiber, the fiber combiner, the gain fiber, the acousto-optic Q switch and the fiber Bragg grating begins to oscillate, triggering the SBS process. After the SBS is started, the feedback controlled by the SMS structure on the left can ensure that the high-order Stokes light has high feedback, so that the inverted population is released quickly. Since the pulse generation and release process is only carried out when the Q switch is turned on, and the SMS structure filters out the low-order Stokes light, ensuring that the high-order Stokes light has high feedback, the wavelength and repetition rate random output characteristics of the SBS self-switched Q laser can be effectively suppressed.

[0026] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A stimulated Brillouin laser based on SMS structure and acousto-optic Q-switch, characterized in that: The invention comprises an SMS structure (1), a third single-mode optical fiber (2), an optical fiber combiner (3), a gain optical fiber (5), an acousto-optic Q switch (6) and an optical fiber grating (7) which are connected in sequence, and at least one pump source (4), wherein the pump source (4) is connected to the optical fiber combiner (3); the SMS structure (1) comprises a first single-mode optical fiber (11), a multimode optical fiber (12) and a second single-mode optical fiber (13) which are connected in sequence, and the second single-mode optical fiber (13) is connected to the third single-mode optical fiber (2).

2. The stimulated Brillouin laser based on SMS structure and acousto-optic Q-switch according to claim 1, characterized in that: The length of the multimode optical fiber (12) is 1 mm to 10 cm.

3. The stimulated Brillouin laser based on SMS structure and acousto-optic Q-switch according to claim 1, characterized in that: The length of the third single-mode optical fiber (2) is greater than or equal to 1 m.

4. The stimulated Brillouin laser based on SMS structure and acousto-optic Q-switch according to claim 1, characterized in that: The end of the first single-mode optical fiber (11) not connected to the multi-mode optical fiber (12) has a bevel angle, and the angle of the bevel angle is 8°.

5. The stimulated Brillouin laser based on SMS structure and acousto-optic Q-switch according to claim 1, characterized in that: The end of the optical fiber Bragg grating (7) not connected to the acousto-optic Q switch (6) has a bevel angle, and the angle of the bevel angle is 8°.

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