A random fiber laser based on random phase-shifted electric grating

Abstract

A random fiber laser based on a random phase-shift grating includes an erbium-doped fiber amplifier, a saturable absorber, an optical isolator, an electro-optic modulator, an optical filter, a 10:90 optical coupler, a polarization controller, a broadband microwave source, a microwave isolator, a microwave circulator and a random phase-shift grating; wherein the random phase-shift grating is composed of an impedance discontinuity point, an outer cladding, an outer conductor, an inner cladding and an inner conductor, and the random phase-shift grating is an impedance discontinuity point obtained by mechanical processing on a coaxial cable. It is used as a new scattering medium in a random laser. The present invention uses a random microwave signal as a control signal to solve the problem of excessive light scattering medium loss and poor directivity in a random laser. The manufacturing process is simple and the parameters are less affected by environmental factors.

Description

Technical Field

[0001] The invention belongs to the field of optical fiber communication and optoelectronic technology, in particular to a random optical fiber laser based on a random phase-shift electric grating. Background Art

[0002] Random laser is a branch in the field of laser with new feedback characteristics. Its novelty lies in removing the optical resonant cavity in the traditional laser. On the basis of sufficient gain in the medium, it uses multiple scattering in the disordered medium to achieve laser lasing. Compared with traditional lasers, fiber random lasers have outstanding advantages such as low phase noise, good stability, and high reliability. They are expected to become a new generation of fiber lasers and be used in optical communications, optical sensing, scattering spot-free imaging, and high-power laser sources. Random lasers currently mainly include filled fiber random lasers, grating random lasers, and single-mode fiber random lasers. The above lasers use optical materials as random feedback media. The laser output efficiency and power are generally very low, and the output is mostly coherent random lasers. There is strong mode competition, and the output laser spectrum and intensity are relatively unstable, which greatly affects its application in sensing and imaging. Summary of the invention

[0003] Based on this, the purpose of the present invention is to provide a random fiber laser based on a random phase-shift grating. It is intended to write a random phase-shift grating on a coaxial cable as a new scattering medium, generate a random microwave signal through the random phase-shift grating, and then add the random signal to the electro-optical modulator to regulate the light intensity, phase and other parameters in the laser. The main research is to study the influence of various parameters of the phase-shift grating on the time domain and frequency domain characteristics of the random signal; to study the influence of parameters such as the fiber dispersion coefficient, nonlinear characteristics, polarization state, and input random microwave signal in the laser on the pulse width, shape and spectral characteristics of the random pulse.

[0004] The technical solution of the present invention:

[0005] A random fiber laser based on a random phase-shift grating consists of an erbium-doped fiber amplifier, a polarization controller, an electro-optic modulator, a microwave circulator, an optical isolator, a saturable absorber, an optical filter, a 10:90 optical coupler, a microwave isolator, a random phase-shift grating and a broadband microwave source. The electro-optic modulator is composed of three ports, a, b and c, wherein port a is the optical input port of the electro-optic modulator, port b is the output port of the electro-optic modulator, and port c is the modulation signal input port. The microwave circulator is composed of three ports, d, e and f, which correspond to the first port, the second port and the third port of the microwave circulator respectively. The 10:90 optical coupler is composed of three ports, g, h and i, wherein g is the 10% port of the 10:90 coupler, h is the 90% port of the 10:90 coupler, and i is the common port of the 10:90 coupler. When the three-port components are connected to form a laser, the ports are not interchangeable, and the remaining devices are composed of two ports. The output end of the erbium-doped fiber amplifier is connected to one end of the saturable absorber. The other end of the receiver is connected to one end of the optical isolator, the other end of the optical isolator is connected to the optical input port of the electro-optic modulator, the output port of the electro-optic modulator is connected to the optical filter, the other end of the optical filter is connected to the common port of the 10:90 coupler, the 90% port of the 10:90 coupler is connected to one end of the polarization controller, the other end of the polarization controller is connected to the input port of the erbium-doped fiber amplifier, the modulation signal input port of the electro-optic modulator is connected to the third port of the microwave circulator, the second port of the microwave circulator is connected to one end of the random phase shift grating, the first port of the microwave circulator is connected to the output port of the microwave isolator, the input port of the microwave isolator is connected to the output port of the broadband microwave source, and the microwave isolator ensures unidirectional transmission of microwaves. The 10% port of the 10:90 optical coupler is used as the output port of the fiber laser. The random phase shift grating is composed of an impedance discontinuity point, an outer cladding, an outer conductor, an inner cladding and an inner conductor. The random phase shift grating is an impedance discontinuity point obtained by mechanical processing on a coaxial cable. The random phase shift grating is connected to the second port of the microwave circulator through a coaxial cable.

[0006] Working principle of the present invention:

[0007] The principle of generating random laser in the random fiber laser structure based on random phase-shift electric grating is as follows: the erbium-doped fiber amplifier is used as the spontaneous radiation source and provides gain for the laser, the polarization controller is used to adjust the polarization state in the cavity, the optical isolator 3 ensures that the light wave runs unidirectionally in the ring cavity, the microwave signal generated by the broadband microwave source first enters the d port of the microwave circulator, and enters the random phase-shift electric grating through the e port of the microwave circulator. After being reflected by the random phase-shift electric grating, a random microwave signal is generated, and then enters again from the e port and outputs from the f port as the modulation signal of the modulator 4. The microwave isolator 9 ensures that the random microwave signal is transmitted unidirectionally. The saturable absorber 2 and the optical filter 5 in the laser structure are the time domain and frequency domain control devices of the random laser, respectively, to control the random laser, the g port of the 10:90 optical coupler 6 is used as the output port of the fiber laser, and the light from the h port enters the laser to re-oscillate.

[0008] The advantages and beneficial effects of the present invention are:

[0009] 1. The random phase-shift electric grid based on the coaxial cable of the present invention can be realized by mechanical processing, the process is simple, and the parameters are less affected by environmental factors.

[0010] 2. The present invention utilizes the control signal reflected by the random phase-shift grating to solve the problems of excessive light scattering medium loss and poor directivity in the random laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The schematic diagram of the structure of the random fiber laser based on the random phase-shifted electric grating of the present invention;

[0012] Figure 2 It is a structural side view of the random phase-shifted grating;

[0013] Figure 3 is a structural cross-sectional diagram of a random phase-shifted grating;

[0014] Figure 4 is the transmission spectrum of the random phase-shift grating;

[0015] Figure 5 is the spectrum of the random laser;

[0016] Figure 6 is the pulse sequence of a random laser.

[0017] In the figure: 1. erbium-doped fiber amplifier, 2. saturable absorber, 3. optical isolator, 4. electro-optic modulator, 5. optical filter, 6. 10:90 optical coupler, 7. polarization controller, 8. broadband microwave source, 9. microwave isolator, 10. microwave circulator, 11. random phase-shift grating; the solid line part in the figure is the optical fiber connection, and the dotted line is the coaxial line connection; the random phase-shift grating 11 is composed of 111, impedance discontinuity point, 112, outer cladding, 113, outer conductor, 114, inner cladding, and 115, inner conductor. DETAILED DESCRIPTION

[0018] like Figure 1 As shown, a random fiber laser based on a random phase-shift grating is composed of an erbium-doped fiber amplifier 1, a saturable absorber 2, an optical isolator 3, an electro-optic modulator 4, an optical filter 5, a 10:90 optical coupler 6, a polarization controller 7, a broadband microwave source 8, a microwave isolator 9, a microwave circulator 10, and a random phase-shift grating 11; wherein the random phase-shift grating 11 is composed of an impedance discontinuity point 111, an outer cladding 112, an outer conductor 113, an inner cladding 114, and an inner conductor 115; the output end of the erbium-doped fiber amplifier 1 is connected to one end of the saturable absorber 2, the other end of the saturable absorber 2 is connected to the input port of the optical isolator 3, the output port of the optical isolator 3 is connected to the optical input port of the electro-optic modulator 4, and the electro-optic modulator 4 The optical output port is connected to the input port of the optical filter 5, the output port of the optical filter 5 is connected to the common port of the 10:90 optical coupler 6, the 90% port of the 10:90 optical coupler 6 is connected to the input port of the polarization controller 7, and the output port of the polarization controller 7 is connected to the input end of the erbium-doped fiber amplifier 1; the microwave input port of the electro-optic modulator 4 is connected to the third port of the microwave circulator 10, the output port of the broadband microwave source 8 is connected to the input port of the microwave isolator 9, the output port of the microwave isolator 9 is connected to the first port of the microwave circulator 10, the second port of the microwave circulator 10 is connected to a port of the random phase-shift electric grating 11, and the 10% port of the 10:90 optical coupler 6 serves as the output port of the fiber laser.

[0019] The random phase shift grating 11 is as follows Figure 2 and Figure 3 As shown, the random phase-shift grating 11 is composed of an impedance discontinuity point 111, an outer cladding 112, an outer conductor 113, an inner cladding 114, and an inner conductor 115. The impedance discontinuity point 111 is obtained by mechanical processing on a coaxial cable. The random phase-shift grating 11 is connected to the third port of the microwave circulator 10 through a coaxial cable.

[0020] The saturable absorber 2 includes: two-dimensional materials such as graphene or black phosphorus, a semiconductor saturable absorber mirror, and an unpumped rare-earth-doped optical fiber.

[0021] The optical filter includes: an optical fiber MZ filter, an optical fiber FP filter, an optical fiber Sagnac filter, an optical fiber Lyot filter and the combination thereof.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A random fiber laser based on a random phase-shifted electric grating, characterized in that: The invention comprises an erbium-doped fiber amplifier (1), a saturable absorber (2), an optical isolator (3), an electro-optic modulator (4), an optical filter (5), a 10:90 optical coupler (6), a polarization controller (7), a broadband microwave source (8), a microwave isolator (9), a microwave circulator (10) and a random phase-shift electric grating (11); wherein the electro-optic modulator (4), the 10:90 optical coupler (6) and the microwave circulator (10) are three-port components, and when the three-port components are connected to form a laser, the ports are not interchangeable, and the remaining components are composed of two ports; the output end of the erbium-doped fiber amplifier (1) is connected to one end of the saturable absorber (2), the other end of the saturable absorber (2) is connected to the input port of the optical isolator (3), the output port of the optical isolator (3) is connected to the optical input port of the electro-optic modulator (4), and the electro-optic modulator (4) is connected to the optical input port of the electro-optic modulator (4). The output port of the optical filter (4) is connected to the input port of the optical filter (5), the output port of the optical filter (5) is connected to the common port of the 10:90 optical coupler (6), the 90% port of the 10:90 optical coupler (6) is connected to the input port of the polarization controller (7), and the output port of the polarization controller (7) is connected to the input end of the erbium-doped fiber amplifier (1); the modulation signal input port of the electro-optic modulator (4) is connected to the third port of the microwave circulator (10), the first port of the microwave circulator (10) is connected to the output end of the microwave isolator (9), the input end of the microwave isolator (9) is connected to the output port of the broadband microwave source (8), the second port of the microwave circulator (10) is connected to a port of the random phase shift electric grating (11), and the 10% port of the 10:90 optical coupler (6) serves as the output port of the fiber laser; The random phase-shift electric grating (11) comprises an impedance discontinuity point (111), an outer cladding (112), an outer conductor (113), an inner cladding (114) and an inner conductor (115); the random phase-shift electric grating (11) is obtained by mechanical processing on a coaxial cable to obtain the impedance discontinuity point (111); the random phase-shift electric grating (11) is connected to a second port of a microwave circulator (10) via a coaxial cable.

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