CN-116345276-B - Multi-wavelength self-selection spectrum synthesis system based on super-fluorescent source

CN116345276BCN 116345276 BCN116345276 BCN 116345276BCN-116345276-B

Abstract

A multi-wavelength self-selective spectral synthesis system based on an super-fluorescent source. The super-fluorescent source is divided into N paths of seed light serving as N synthetic arms through a beam splitter, and the seed light is converged on the diffraction grating at a corresponding angle after passing through a focusing system together. For each individual composite arm, only the light with specific wavelength corresponding to the end cap position can return in the original path after being reflected by the 0-degree plane mirror, and is re-coupled into each composite arm, and is re-injected into the optical fiber main amplifier after passing through the pre-amplifier, and the self-selection of the wavelength is realized in the main amplifier through the gain competition process. The invention has the advantages of self-selection of wavelength, simple and compact structure, strong expansibility of the number of synthetic routes and the like. The super-fluorescent source is not only a seed source, but also can protect the fiber laser system from self-oscillation when the system is disturbed by the environment and loses feedback light, and improves the safety. The synthetic light wavelength is selected by the system independently, so that the phenomenon of the directional drift of the synthetic light beam caused by factors such as the drift of the seed wavelength, the mechanical shake of the end cap and the like can be effectively overcome.

Inventors

MENG JUNQING
Shao Qianhe
YANG YIFENG
LI BINGLIN
CHEN WEIBIAO

Assignees

中国科学院上海光学精密机械研究所

Dates

Publication Date: 20260512
Application Date: 20230317

Claims (5)

1. A multi-path wavelength self-selection spectrum synthesis system based on an super-fluorescence source is characterized by comprising the super-fluorescence source, a 1xN beam splitter, N synthesis arms, a focusing system, a diffraction grating, a 45-degree plane reflector, a small aperture diaphragm and a 0-degree plane reflector, wherein each synthesis arm comprises a 2x1 beam combiner, an optical fiber main amplifier, an optical fiber preamplifier, a circulator and an optical fiber output end cap, the super-fluorescence source is divided into N paths of seed light through the 1xN beam splitter, each path of seed light sequentially passes through the 2x1 beam combiner, the optical fiber main amplifier and the circulator, a wide-spectrum light beam is output through a port ② of the circulator, and is converged to the diffraction grating for synthesis at different angles, and after passing through the 45-degree reflector, main power is reflected and output, and trace transmission light is incident on the 0-degree reflector; to ensure that the feedback light obtains gain competition in the optical fiber amplifier and thus stable oscillation light beam output, the reflectivity R of the 45-degree plane mirror and the amplification factor of the optical fiber amplifier Magnification of pre-amplification 13 The following criteria should be satisfied: wherein A is the insertion loss of the circulator, B is the coupling efficiency of the optical fiber end cap 7, C is the diffraction efficiency of the multilayer dielectric reflection type diffraction grating, and D is the feedback optical power duty ratio.
2. The system of claim 1, wherein the 45 ° plane mirror has a reflection wavelength range covering a synthetic wavelength band, a front side coated with a high reflection film, and a back side coated with an antireflection film.
3. The system for synthesizing the multiple wavelength self-selection spectrum based on the super-fluorescent light source according to claim 1, wherein the 0-degree plane mirror and the aperture diaphragm are used as feedback elements, the wavelength range of the reflection surface of the 0-degree plane mirror covers the synthesized wave band, the front surface is plated with a high reflection film, the back surface is plated with an antireflection film, the optical axis of the aperture diaphragm is overlapped with the synthesized light beam, and the diameter is less than or equal to 1/e 2 of the synthesized light beam.
4. The system of claim 1, wherein the backward feedback light is re-coupled to each combining arm through a port ② of the circulator, and is output from a port ③ of the circulator, amplified by the optical fiber pre-amplifier, and re-enters the optical fiber main amplifier for amplification by the 2x1 combiner, so as to realize the wavelength self-selection of each combining arm.
5. The system of claim 1, wherein the focusing system is an off-axis reflector system or an on-axis transmissive system.

Description

Multi-wavelength self-selection spectrum synthesis system based on super-fluorescent source Technical Field The invention mainly relates to the field of optical fiber laser spectrum synthesis, in particular to an optical fiber laser spectrum synthesis system which is applicable to high power and high brightness and can realize wavelength self-selection. Background The fiber laser has the advantages of compact structure, good beam quality, high conversion efficiency, convenient thermal management and the like. Currently, the output power of a single-fiber laser breaks through 20 kilowatts. But is limited by nonlinear effects of the medium, fiber end face damage, mode instability and other factors, and further improvement of the output power of the single-fiber laser is limited. Therefore, synthesizing multiple lasers by coherent or incoherent means is an effective means of achieving its power expansion. Spectral synthesis is a non-coherent synthesis technology, has no requirement on the phase of sub-beam laser, can realize common aperture synthesis, can realize the beam quality near the diffraction limit, and is a better choice for realizing high-power and high-brightness output of an optical fiber laser. Spectral synthesis is the inverse of chromatic dispersion, and sub-beams of different wavelengths incident at different angles are emitted at the same angle by using a dispersive element. Depending on the dispersive element used, it can be divided into synthetic techniques based on prisms, dichroic plates, volume bragg gratings, diffraction gratings, etc. The spectrum synthesis scheme adopting the multilayer dielectric reflection type diffraction grating has the excellent characteristics of strong dispersion capability, high efficiency, high damage threshold and the like, and becomes a main scheme in the spectrum synthesis technology. The spectrum synthesis technology based on the multilayer dielectric reflective diffraction grating has the following bottleneck problems: (1) Each sub-beam laser of the spectrum synthesis system needs a specific wavelength, and wavelength deviation can influence the consistency of the direction of the synthesized light, so that the wavelength of each sub-beam needs to be accurately adjusted, and the reliability and the stability of the system are reduced to a certain extent. (2) In the operation process of an actual system, key elements such as an optical fiber end cap, a reflecting mirror and the like are influenced by environmental mechanical vibration, thermal distortion and the like, so that sub-beams are led to point offset, and point compensation is required to be carried out through wavelength on-line adjustment, so that the stability of the system is further reduced. (3) The spectrum synthesis system of the external cavity type oscillation structure has higher self-organizing threshold value, and when the system loses feedback light at the beginning of free running or when a space optical system is disturbed by environment, the amplifier is easy to generate self-oscillation, so that irreversible optical damage is caused. The above factors affect the efficiency and quality of the synthesized light beam of the spectrum synthesis system, and the safety of the spectrum synthesis system has hidden trouble, so it is highly desirable to develop a spectrum synthesis system with on-line independent adjustment of the sub-beam wavelength and high reliability. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a spectrum synthesis system which has low cost, compact structure, strong expansibility of array scale and automatic selection of wavelength by the system, and the environment stability and the safety of the spectrum synthesis system are improved. The technical scheme of the invention is as follows: A multi-wavelength self-selection spectrum synthesis system based on an super-fluorescent source comprises the super-fluorescent source, a 1xN beam splitter, N synthesis arms, a multi-layer dielectric reflection diffraction grating, a focusing system, a 45-degree plane mirror, a small aperture diaphragm and a 0-degree plane mirror, wherein the synthesis arms comprise 12 x1 beam combiners, 1 optical fiber main amplifiers, 1 optical fiber preamplifiers, 1 circulators and 1 optical fiber tail end output devices, the circulator comprises ports ①②③, the super-fluorescent source is divided into N paths by the beam splitter to serve as synthesis seed light, the N paths of the synthesized seed light are amplified and then enter from circulator ports ①, the ports ② and then output spatial light through the optical fiber tail end output devices, the N paths of output light are sequentially arranged in parallel with the grating dispersion surface in space, the N paths of output light are emitted in parallel and are converged onto the diffraction grating at different angles after jointly passing through the focusing system, and common aperture