Device for generating high-energy ultrashort pulses and working method thereof

Abstract

The invention relates to a device for generating high-energy ultrashort pulses and a working method thereof. The device comprises a femtosecond laser front end, a pre-chirp management unit, a pulse separation unit, a nonlinear optical fiber amplification unit, a pulse synthesis unit and a pulse compression unit. The front end of the femtosecond laser emits a line bias pulse sequence; the pulse pre-chirp amount of the line offset pulse sequence is adjusted through a pre-chirp management unit; the pulse separation unit separates the pre-chirped pulse into a plurality of pulses in time; the non-linear optical fiber amplification unit performs power amplification on the separated pulses; the pulse synthesis unit combines the amplified pulses in time so as to obtain pulses with higher energy; and the pulse compression unit is used for compressing the synthesized high-energy pulse to obtain an ultra-short high-energy pulse. On the basis of the advantage that the pre-chirp amplification technology can generate the sub-50fs pulse, the sub-pulse amplification technology is combined to break through the upper limit of single pulse energy, and the 200W sub-50fs ultra-short femtosecond pulse can be directly generated in a large-mode-area optical fiber amplification system.

Description

Technical field [0001] The invention relates to the technical fields of nonlinear fiber optics and femtosecond lasers, in particular to a method and device for generating high-energy femtosecond pulsed lasers with high efficiency. Background technique [0002] Femtosecond laser drive source with high repetition frequency and high energy is the key to construct high-throughput harmonic source. Compared with solid-state lasers such as Ti:Sapphire, fiber lasers have natural heat dissipation advantages, which makes fiber lasers the first choice for high repetition frequency femtosecond lasers. At present, the commonly used solution in fiber lasers is based on the chirped pulse amplification technology (CPA) of the grating to the compressor. In this technology, the seed pulse input to the stretcher can be fully stretched to the order of nanoseconds to ensure that the pulse is in The approximately linear amplification in the amplifier avoids non-linear effects. Therefore, a large-size...

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Problems solved by technology

Since the pulse width in the main amplifier stage of the pre-chirp management amplification technology is generally maintained at about 1ps, it is limited by the self-focusing threshold of the silica fiber (4MW / cm 2 ), the pulse energy output by this method is severely limited to 2-4 microjoules, and it is difficult to continue to climb;

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