Design of High-Gain Single-Stage and Single-Pass Nd:YVO4 Amplifier Pumped by Fiber-Coupled Laser Diodes: Simulation and Experiment

In this paper, factors influencing the performance of high-gain Nd:YVO 4 amplifiers are analyzed and a schematic map of the relationships between different factors is given. A model, including the pump absorption saturation effect and overlap efficiency along the beam propagation direction, as well as non-radiative decays due to high doping concentration, is developed. The performance of laser amplifier is studied by changing doping concentration, pump beam quality, and focal size of pump laser. To get high gain, samples with low doping concentration should cooperate with long crystals and laser diodes with good beam quality. Based on the model, the focal radius of pump laser could be optimized for different doping concentrations and beam qualities of pump laser. Experiments were conducted and the results agreed well with the simulated ones. Moreover, a single-stage and single-pass amplifier was realized, achieving a small-signal gain of 51 dB.