Fiber laser amplifier with high stimulated Brillouin scattering threshold and high conversion efficiency

Abstract

The invention discloses a fiber laser amplifier with a high stimulated Brillouin scattering threshold and high conversion efficiency. The fiber laser amplifier comprises a to-be-amplified laser port,a forward pump light port, a forward signal / pump coupler, a gain fiber, a second fiber bragg grating and an amplified laser exit port which are sequentially arranged on a laser amplification light path. When to-be-amplified laser of the fiber laser amplifier is amplified by the high-power fiber laser amplifier, the corresponding fiber bragg gratings are added to the two ends of the gain fiber, sothat pump light can be transmitted twice in the gain fiber, the use length of the gain fiber is shortened, the SBS total gain of the fiber laser amplifier is reduced, and the service life of the fiberlaser amplifier is prolonged. Therefore, the SBS threshold of the fiber laser amplifier is improved, and higher-power narrow-linewidth laser output is realized.

Description

technical field [0001] The invention relates to the technical field of increasing the stimulated Brillouin scattering threshold of a high-power fiber laser amplifier, in particular to a fiber laser amplifier with a high stimulated Brillouin scattering threshold and high conversion efficiency. Background technique [0002] With the development of science and technology and economic growth, in the field of industrial manufacturing, higher and higher requirements are placed on the output power and conversion efficiency of laser systems. However, in the case of high power, the fiber laser amplifier is limited by the stimulated Brillouin scattering effect (hereinafter referred to as SBS), and it is difficult to increase the output power. Moreover, in the case of high power, the low conversion efficiency of the laser will convert a large amount of pump light into waste heat, which greatly increases the heat dissipation cost. A variety of schemes have been proposed to suppress the...

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Problems solved by technology

However, in the case of high power, the fiber laser amplifier will be limited by the stimulated Brillouin scattering effect (hereinafter referred to as SBS), and it is difficult to increase the output power.

Moreover, in the case of high power, the low conversion efficiency of the laser will convert a large amount of pump light into waste heat, which greatly increases the cooling cost

A variety of schemes have been proposed to suppress the SBS phenomenon in fiber laser amplifiers, such as increasing the doping concentration of the gain fiber to increase the absorption coefficient, shortening the length of the gain fiber to increase the SBS threshold of the laser, but too high a doping concentration will The generation of ion clusters inside the gain fiber degrades the performance of the fiber. At the same time, the use of a gain fiber with an excessively high absorption coefficient can easily reduce the mode instability threshold (MI) of the laser, deteriorating the beam quality; another example can be to design a special fiber to reduce the SBS gain coefficient, but this method will make the fiber design difficult, the fiber drawing process is complicated, and the current application effect is not ideal; and the application of special components / structure fibers will greatly increase the cost of fiber laser amplifiers; The method of applying stress causes the SBS gain spectrum of the fiber to move, and the SBS gain spectrum at different positions of the same fiber has staggered peaks to suppress the SBS phenomenon in the fiber. However, this method requires precise control of applying different stresses to the fibers at different positions, resulting in The overall structure of the fiber laser amplifier becomes complicated, which reduces the reliability of the fiber laser amplifier and increases the production cost, which is not conducive to the commercialization of the laser

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