The Research On High-Power Er³⁺-Yb³⁺ Codoped Pulsed Fiber Amplifier

High-power Er-Yb codoped fiber amplifiers(EYDFAs) working in the 1.5 ?m band, have many merits, such as ‘eye safe', low transmission loss in fiber and in atmosphere. They can be used in space communication, military, medical treatment and scientific research etc. As high power pulsed laser is typically required in these fields, the interest of researching on high-power pulsed EYDFAs is becoming a research hot-spot.In this thesis, high-power pulsed EYDFAs are studied both theoretically and experimentally. The main work of this thesis are summarized below:A theoretical model of high-power Er-Yb codoped pulsed fiber amplifier based on the rate equations and power transfer equations of Er-Yb codoped system is developed. Through numerical solution of this model with the finite difference method, the influence of the parameters of the pump, signal, and gain fiber on performance of highpower Er-Yb codoped pulsed fiber amplifiers has been systematically analyzed. Lowrepetition rate pulse-pumped EYDFA is also analyzed numerically. The results show that there are exist an optimal EYDF length and signal frequency. The influence of the peak power and pulse width of the signal also have influences on the performance of the EYDFA; the Yb-ASE induced parasitic lasing can be solved by pulsed-pumping and optimizing of the timing between the signal and pump pulses.A forward-pumped high-power EYDFA with a two-stage MOPA structure was built and experimentally studied. The signal pulse with a peak power of 32 mW, pulse-width of 200 ns, and repetition rate of 100 kHz was amplified to an average power of 52.40 mW after the first-stage amplifier, an Er-codoped fiber amplifier, through the Er-Yb codoped fiber amplifier, it was amplified to an average power of ~3.7 W. The equivalent peak power is ~185 W. The experimental and theoretical results agrees very well qualitatively.