Double-Brillouin frequency wavelength interval multi-wavelength fiber laser with double output ports

Abstract

The invention discloses a double-Brillouin-frequency-wavelength-interval multi-wavelength fiber laser with double output ports. The double-Brillouin-frequency-wavelength-interval multi-wavelength fiber laser comprises a narrow-linewidth laser, a first optical circulator, an optical fiber coupler, a first optical amplifier, a first single-mode fiber, a second optical amplifier, a second optical circulator and a second single-mode fiber. On the basis of the stimulated Brillouin scattering effect in the first single-mode optical fiber and the second single-mode optical fiber and the light amplification effect of the first optical amplifier and the second optical amplifier, even-order Brillouin Stokes light with the wavelength interval being two times of the Brillouin frequency can be obtained at the two output ports, and multi-wavelength optical signals output by the two output ports have the twinning characteristic. The multi-wavelength optical fiber laser has the advantages of being simple in structure, low in cost and good in stability, and has good application prospects in the fields of the optical fiber communication technology, the microwave photon technology and the optical fiber sensing technology.

Description

Technical Field

[0001] The present invention relates to a multi-wavelength fiber laser, in particular to a multi-wavelength Brillouin-erbium fiber laser with a double Brillouin frequency interval and dual output ports, belonging to the technical field of optical fiber communication. Background Art

[0002] Multi-wavelength Brillouin-erbium fiber lasers utilize the dual advantages of stimulated Brillouin scattering (SBS) in optical fibers and the linear gain of erbium-doped fibers. They are easily generated at room temperature, are tunable, and offer numerous advantages, including narrow linewidth, low threshold, and fixed wavelength spacing. They hold broad application prospects in optical communications, fiber optic sensors, spectroscopy, frequency combs, and microwave photonics.

[0003] The wavelength channel spacing of existing multi-wavelength Brillouin fiber lasers is mostly a single Brillouin frequency shift wavelength spacing, which makes wavelength division multiplexing difficult. Reported works, such as Chin.Physis.Lett., 30(2), (2013)024205, Opt.Laser Technol., 2011, 43(4), 866-869, IEEE Photonics.Technol.Lett., 30(5), 2018; ZL201811221435.3, etc., either propose a single-port output of a multi-wavelength Brillouin fiber laser with a double Brillouin frequency shift spacing, or a dual-port output of odd-order and even-order Brillouin Stokes light, respectively. However, there are almost no reports on Brillouin multi-wavelength lasers that simultaneously obtain even-order Stokes light at dual ports. In fact, a multi-wavelength fiber laser that outputs both even-order Brillouin Stokes light or odd-order Brillouin Stokes light at dual ports is of great significance in some applications. Because, in some wavelength division multiplexing communication systems, the multi-wavelength communication light source has two output ports with the same output characteristics, which is particularly important in applications that require main and backup communication light sources. Summary of the Invention

[0004] The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval and dual output ports proposed by the present invention includes a narrow linewidth laser, a first optical circulator, an optical fiber coupler, a first optical amplifier, a first single-mode optical fiber, a second optical circulator, a second optical amplifier, and a second single-mode optical fiber.

[0005] The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval of the dual-output port is characterized in that the output port of the narrow linewidth laser (1) is connected to the first port (21) of the first optical circulator (2), the second port (22) of the first optical circulator (2) is connected to the port 32 of the optical fiber coupler (3), the port 33 of the optical fiber coupler (3) is connected to one end of the first optical amplifier (4), the other end of the first optical amplifier (4) is connected to one end of the first single-mode optical fiber (5), the other end of the first single-mode optical fiber (5) is connected to the port 31 of the optical fiber coupler (3), and the port 34 of the optical fiber coupler (3) is the first output port of the multi-wavelength fiber laser; the third port (23) of the first optical circulator (2) is connected to one end of the second optical amplifier (6), the other end of the second optical amplifier is connected to the first port 71 of the second optical circulator (7), the second port 72 of the second optical circulator is connected to one end of the second single-mode optical fiber (8), and the third port (73) of the second optical circulator (7) serves as the second output port of the multi-wavelength fiber laser.

[0006] In the multi-wavelength fiber laser with a dual-output port and a wavelength interval of twice the Brillouin frequency, the first single-mode fiber, the fiber coupler, and the first optical amplifier are connected to form a first optical branch, i.e., a 33-4-5-31-33 optical branch. Port 34 of the fiber coupler serves as the output port of the first optical branch and is also the first output port of the multi-wavelength fiber laser. The second optical amplifier, the second optical circulator, and the second single-mode fiber are connected to form a second optical branch, i.e., a 6-71-72-8-73 optical branch. Port 73 of the second optical circulator serves as the output port of the second optical branch and is also the second output port of the multi-wavelength fiber laser.

[0007] The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval of the dual-output port is characterized in that the narrow-linewidth laser (1) outputs a narrow-linewidth laser as a Brillouin pump (BP). The BP enters the first optical branch from the first port (21) and the second port (22) of the first optical circulator (2) and is first split through the port 32 of the optical fiber coupler (3). Then, a part of the BP is output from the port 34 of the optical fiber coupler (3), that is, from the first output port of the multi-wavelength fiber laser. The other part of the BP enters the first optical branch and is split through the port 32 of the optical fiber coupler (3). Then, the BP enters the first optical amplifier (4) for amplification at the port 33 and is then injected into one end of the first single-mode optical fiber (5). When this part of the BP (BP can be regarded as zero-order Brillouin Stokes light, it can be seen that When the power of BS0) is greater than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5), a first-order Brillouin Stokes light (BS1) with a frequency shifted down by one Brillouin frequency shift relative to BP will be generated. BS1 is transmitted clockwise through the 31 port of the optical fiber coupler (3) and enters the first single-mode optical fiber (5). When its power is greater than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5), a second-order Brillouin Stokes light (BS2) with a frequency shifted down by one Brillouin frequency shift relative to BS1 will be generated. The transmission condition of BS2 is the same as that of BS0. This is deduced until the power of the 2n+1 order Stokes light amplified by the first amplifier (4) is less than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5). Then BS0, BS2, BS4, ..., BS 2n Even-order Brillouin-Stokes light is output from port 34 of the fiber coupler, which is the first output port of the multi-wavelength fiber laser. 2n+1 The odd-order Brillouin Stokes light enters the second optical branch through ports 33 and 32 of the optical fiber coupler (3) and ports 22 and 23 of the first optical circulator (2), is first transmitted to the first port (71) of the second optical circulator (7) through the second optical amplifier (6), and enters the second single-mode optical fiber (8) from the second port (72) of the second circulator. When the power is greater than the stimulated Brillouin scattering threshold of the second single-mode optical fiber (8), even-order Brillouin Stokes light BS2, BS4, ..., BS4 with a frequency relatively shifted downward by one Brillouin frequency shift is generated accordingly. 2n ,BS 2n+2 These even-order Brillouin-Stokes lights are output through the third port (73) of the second optical circulator (7), that is, the second output port of the multi-wavelength fiber laser.

[0008] The present invention utilizes a narrow-linewidth laser, two optical circulators, a fiber coupler, two optical amplifiers, and two spools of single-mode optical fiber with the same Brillouin frequency shift. Each single-mode optical fiber is 10 km long. The narrow-linewidth laser is a C-band narrow-linewidth laser with continuously tunable output wavelength and power, achieving a maximum output power of 15 dBm and a linewidth of less than 1 MHz. The first and second optical amplifiers are each composed of a 980 nm pump laser, a 5 m long erbium-doped fiber, and a 1550 / 980 wavelength division multiplexer, enabling bidirectional amplification of optical signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the composition structure of a multi-wavelength fiber laser with a wavelength spacing of twice the Brillouin frequency of the dual output ports.

[0010] Figure 1 The reference numerals in the figure are explained as follows: 1-narrow linewidth laser, 2-first optical circulator, 21, 22, 23 are the first port, second port and third port of the first optical circulator, respectively, 3-fiber coupler, 31, 32, 33, 34 are the four ports of the fiber coupler, respectively, 4-first optical amplifier, 5-first single-mode optical fiber, 6-second optical amplifier, 7-second optical circulator, 71, 72, 73 are the first port, second port and third port of the second optical circulator, respectively, 8-second single-mode optical fiber. DETAILED DESCRIPTION

[0011] The technical solution of the present invention is further described below with reference to the accompanying drawings. like Figure 1 The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval and dual output ports includes a narrow linewidth laser, a first optical circulator, a fiber coupler, a first optical amplifier, a first single-mode fiber, a second optical amplifier, a second optical circulator, and a second single-mode fiber.

[0012] The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval of the dual-output port is characterized in that the output port of the narrow linewidth laser (1) is connected to the first port (21) of the first optical circulator (2), the second port (22) of the first optical circulator (2) is connected to the port 32 of the optical fiber coupler (3), the port 33 of the optical fiber coupler (3) is connected to one end of the first optical amplifier (4), the other end of the first optical amplifier (4) is connected to one end of the first single-mode optical fiber (5), the other end of the first single-mode optical fiber (5) is connected to the port 31 of the optical fiber coupler (3), and the port 34 of the optical fiber coupler (3) is the first output port of the multi-wavelength fiber laser; the third port (23) of the first optical circulator (2) is connected to one end of the second optical amplifier (6), the other end of the second optical amplifier is connected to the first port 71 of the second optical circulator (7), the second port 72 of the second optical circulator is connected to one end of the second single-mode optical fiber (8), and the third port (73) of the second optical circulator (7) serves as the second output port of the multi-wavelength fiber laser.

[0013] In the multi-wavelength fiber laser with a dual-output port and a wavelength interval of twice the Brillouin frequency, the first single-mode fiber, the fiber coupler, and the first optical amplifier are connected to form a first optical branch, i.e., a 33-4-5-31-33 optical branch. Port 34 of the fiber coupler serves as the output port of the first optical branch and is also the first output port of the multi-wavelength fiber laser. The second optical amplifier, the second optical circulator, and the second single-mode fiber are connected to form a second optical branch, i.e., a 6-71-72-8-73 optical branch. Port 73 of the second optical circulator serves as the output port of the second optical branch and is also the second output port of the multi-wavelength fiber laser.

[0014] The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval of the dual-output port is characterized in that the narrow-linewidth laser (1) outputs a narrow-linewidth laser as a Brillouin pump (BP). The BP enters the first optical branch from the first port (21) and the second port (22) of the first optical circulator (2) and is first split through the port 32 of the optical fiber coupler (3). Then, a part of the BP is output from the port 34 of the optical fiber coupler (3), that is, from the first output port of the multi-wavelength fiber laser. The other part of the BP enters the first optical branch and is split through the port 32 of the optical fiber coupler (3). Then, the BP enters the first optical amplifier (4) for amplification at the port 33 and is then injected into one end of the first single-mode optical fiber (5). When this part of the BP (BP can be regarded as zero-order Brillouin Stokes light, it can be seen that When the power of BS0) is greater than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5), a first-order Brillouin Stokes light (BS1) with a frequency shifted down by one Brillouin frequency shift relative to BP will be generated. BS1 is transmitted clockwise through the 31 port of the optical fiber coupler (3) and enters the first single-mode optical fiber (5). When its power is greater than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5), a second-order Brillouin Stokes light (BS2) with a frequency shifted down by one Brillouin frequency shift relative to BS1 will be generated. The transmission condition of BS2 is the same as that of BS0. This is deduced until the power of the 2n+1 order Stokes light amplified by the first amplifier (4) is less than the stimulated Brillouin scattering threshold of the first single-mode optical fiber (5). Then BS0, BS2, BS4, ..., BS 2n Even-order Brillouin-Stokes light is output from port 34 of the fiber coupler, which is the first output port of the multi-wavelength fiber laser. 2n+1 The odd-order Brillouin Stokes light enters the second optical branch through ports 33 and 32 of the optical fiber coupler (3) and ports 22 and 23 of the first optical circulator (2), is first transmitted to the first port (71) of the second optical circulator (7) through the second optical amplifier (6), and enters the second single-mode optical fiber (8) from the second port (72) of the second circulator. When the power is greater than the stimulated Brillouin scattering threshold of the second single-mode optical fiber (8), even-order Brillouin Stokes light BS2, BS4, ..., BS4 with a frequency relatively shifted downward by one Brillouin frequency shift is generated accordingly. 2n ,BS 2n+2 These even-order Brillouin-Stokes lights are output through the third port (73) of the second optical circulator (7), that is, the second output port of the multi-wavelength fiber laser.

[0015] The narrow linewidth laser is a C-band narrow linewidth laser, the output wavelength and power of which can be continuously tuned, the maximum output power is 15dBm, and the linewidth is less than 1MHz.

[0016] The first and second optical amplifiers are both connected by a 980nm pump laser, a 5m long erbium-doped optical fiber and a 1550 / 980WDM.

[0017] The length of the first and second single-mode optical fibers is 10 km, and the Brillouin frequency shift is approximately 10.88 GHz.

[0018] The working process of the present invention is described in detail above. For those skilled in the art, based on the concept provided by the present invention, there may be changes in the specific implementation method, such as changing the position of the optical amplifier module, changing the splitting ratio of the optical fiber coupler and the length of the single-mode optical fiber in the optical path, etc. These changes should also be considered within the scope of protection of the present invention.

Claims

1. The multi-wavelength fiber laser with a double Brillouin frequency wavelength interval of the dual output port comprises a narrow linewidth laser (1), a first optical circulator (2), an optical fiber coupler (3), a first optical amplifier (4), a first single-mode optical fiber (5), a second optical amplifier (6), a second optical circulator (7), and a second single-mode optical fiber (8); the output port of the narrow linewidth laser is connected to the first port (21) of the first optical circulator, the second port (22) of the first optical circulator is connected to the port 32 of the optical fiber coupler, the port 33 of the optical fiber coupler is connected to one end of the first optical amplifier, the other end of the first optical amplifier is connected to one end of the first single-mode optical fiber, the other end of the first single-mode optical fiber is connected to the port 31 of the optical fiber coupler, and the optical fiber coupler is connected to the first port (21) of the first optical circulator. The port 34 of the combiner serves as the first output port of the multi-wavelength fiber laser, the third port (23) of the first optical circulator is connected to the second optical amplifier, the second optical amplifier is connected to the first port (71) of the second optical circulator, the second port (72) of the second optical circulator is connected to one end of the second single-mode optical fiber, and the third port (73) of the second optical circulator serves as the second output port of the multi-wavelength Brillouin-Erbium fiber laser. Based on the optical path structure, it is expected that even-order Brillouin Stokes light with a wavelength interval of twice the Brillouin frequency can be obtained at both output ports. Since the first output port has only one more Brillouin pump light than the second output port, the two output optical signals are basically the same, and thus the two output ports have the characteristics of "twin" ports.

2. The multi-wavelength fiber laser with a wavelength spacing of twice the Brillouin frequency and dual output ports according to claim 1, characterized in that: The optical ring path 33-4-5-31-33 constitutes the first optical branch of the multi-wavelength fiber laser, and the first output port outputs even-order Brillouin-Stokes light. The optical path 7-61-62-8-62-63 constitutes the second optical branch of the multi-wavelength fiber laser, and the second output port also outputs even-order Brillouin-Stokes light.

3. The multi-wavelength fiber laser with a wavelength spacing of twice the Brillouin frequency and dual output ports according to claim 1, characterized in that: The first optical amplifier and the second optical amplifier can both bidirectionally amplify optical signals.

4. The multi-wavelength fiber laser with a double Brillouin frequency wavelength spacing and dual output ports according to claim 1, characterized in that: The first single-mode optical fiber and the second single-mode optical fiber have the same Brillouin frequency shift value.

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