High-energy low-repetition-frequency fiber laser

Abstract

The invention relates to a high-energy low-repetition-frequency fiber laser, which comprises a pump light source used for providing energy for generating laser light, a gain fiber used for providing gains, a mode locking device used for modulating the laser light so as to generate ultrashort pulses, and a single-mode transmission fiber used for laser transmission, wherein the gain fiber, the single-mode transmission fiber and the mode locking device form a resonant cavity of the fiber laser; the generated laser light is oscillated in the resonant cavity; and under the condition that the lengths of the gain fiber and the mode locking device are not increased, the length of the single-mode transmission fiber is increased according to a relation that the length L of the resonant cavity is inversely proportional to the repetition frequency frep of the fiber laser and according to the reduction of the needed repetition frequency frep. By increasing the length of the resonant cavity, the high-energy low-repetition-frequency fiber laser reduces the repetition frequency of pulses in the resonant cavity, correspondingly improves the energy of a single pulse, further simplifies the structure of an amplification system, improves the efficiency of an amplifier and effectively reduces the cost.

Description

technical field [0001] The invention relates to the field of mode-locked fiber lasers and amplifiers, in particular to a fiber laser with high energy and low repetition frequency. Background technique [0002] Mode-locked fiber laser refers to an experimental device that uses mode-locked technology to generate femtosecond and picosecond ultrashort pulses in fiber lasers. Mode-locking technology is a method of modulating a laser beam, so that different longitudinal modes of oscillation in the beam have a definite phase relationship, so that each mode can be coherently superimposed to obtain an ultrashort pulse. In general, ultrashort pulses refer to femtosecond and picosecond pulses, where 1 femtosecond = 1×10 -15 Second, 1 picosecond = 1×10 -12 Second. General mode-locked fiber lasers use semiconductor lasers as pump light sources, use special fibers doped with rare earth elements as gain fibers, use single-mode fibers as basic components in the laser cavity, and use the ...

AI Technical Summary

Problems solved by technology

However, this kind of photonic crystal fiber has great disadvantages: it is very expensive and monopolized by foreign companies (such as Crystal Fiber in Denmark), and welding is very difficult (ordinary fusion splicers cannot be welded and need to be welded by the original factory), etc.

In other words, if the cavity length of the laser is lengthened (that is, the length of the single-mode fiber in the cavity is increased), the nonlinear polarization rotation technology is not as good as the mode-locking effect of the saturable absorption method.

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