Numerical Model of Chirped Pulse Amplification in Pulsed Synchronously Pumped Low-Repetition-Rate Fiber Amplifiers

We propose a numerical model to simulate amplification in a pulsed synchronously pumped chirped pulse amplifier (CPA) operating at a low repetition rate. The generalized nonlinear Schrödinger equation and dynamic rate equations are employed to facilitate an accurate treatment of time-space-dependent-gain, wavelength-dependent saturation energy, nonlinearity, and dispersion. Because of an accurate instantaneous gain term, the model can adequately explain pulse distortion and spectral redshift during amplification. The bidirectional amplified spontaneous emission, final output energy, and evolution of temporal and spectral intensities are also investigated through simulations. In addition, a pulsed synchronously pumped CPA fiber system is estbalished to validate the model. The experimental results for the wave shape, spectrum and energy show excellent agreement with those of simulations.