Theoretical and optimized design of low-repetition-rate high-energy pulse amplification in multi-stage MOPA systems

Abstract

Based on the modeling of a fiber amplification system, a closed form rate and power evolution equation for low-repetition-rate pulse amplification in a multi-stage fiber master-oscillator-power-amplifier (MOPA) is constructed. In order to ensure a high-energy conversing efficiency at the lowest cost, a novel multi-stage optimization method is proposed for the optimization of the multi-stage MOPA system. Differently from the individual optimization method for single fiber amplifiers, every stage amplifier is considered as a part of the whole system and optimized by analyzing the final output pulse energy. As an example, the system parameters of a two stage ytterbium-doped fiber MOPA system including the fiber length, pump power, and peak power of the seed source are optimized by using the proposed method. Under the condition of obtaining almost the same output pulse energy, the fiber length and pump power of the first stage optimized by the new method are, respectively, shorter and lower, 1.6 m and 57.3 W, than those optimized by the individual optimization method. Meanwhile, the optimization results also show that increasing the input signal energy is not an effective way to increase the output energy. The proposed theoretical optimization method can provide an important guide for the design and optimization of the low-repetition-rate pulse amplification in a multi-stage MOPA system.

Modeling of a dual-wavelength fiber amplification system for further mid-infrared generation

“…Due to its high surface-area-tovolume ratio, the fiber laser system overcomes heat dissipation problems, provides higher average power, and realizes stable and alignment-free operation. There are many research efforts working on the fiber amplification theoretical model [24][25][26][27][28][29][30][31][32][33]. Early studies focused on the steady-state of the fiber system [24][25][26][27][28], and recent studies show more complicated works were centered on the behavior of the pulse amplification by combining the laser rate and Ginzburg-Landau equations [29][30][31][32][33], which took nonlinearity and dispersion into consideration.…”

“…There are many research efforts working on the fiber amplification theoretical model [24][25][26][27][28][29][30][31][32][33]. Early studies focused on the steady-state of the fiber system [24][25][26][27][28], and recent studies show more complicated works were centered on the behavior of the pulse amplification by combining the laser rate and Ginzburg-Landau equations [29][30][31][32][33], which took nonlinearity and dispersion into consideration. However, there is not too much theoretical research working on the dual-wavelength fiber amplifier due to the complexity of gain competition during amplification and amplified spontaneous emission (ASE) between the two wavelength regions.…”

Theory of noise in a kilo-Hz cascaded high-energy Yb-doped nanosecond pulsed fiber amplifier

“…With the development of pulsed fiber lasers, more and more extremely high records of output pulses are published including highest peak power, highest pulse energy, highest average power, etc. [1][2][3][4][5][6][7][8][9][10] However, as far as we know, the analysis on high power pulsed system back ground noise has sel-dom been made. And most noise theories are based on the application of fiber communications, [1,2] in which the noise is high frequency coherent interference signal that usually increases the bit error rate.…”

“…In Ref. [8] a numerical model analysis on low repetition rate multistage MOPA systems was made representatively. However, the ASE noise transfer between stages is not considered, and the pumping procedure is analyzed by steady state for a very low repetition rate.…”

A 12 mJ 11 ns spectrally narrow fiber amplifier with a pulsed pump

“…determine the optimum input pulse-shape required to obtain any arbitrary target pulse-shape at the output of the saturated laser amplifier, and the relation was experimentally verified using an all-fiber amplifier [7]. In 2010, Li constructed a closed form rate and power evolution equation for a low-repetitionrate multi-stage fiber amplifier [8]. By using the equation, the fiber length, pump power, and peak power of the seed source are optimized.…”