Research On All-fiberized Yb Fiber Laser With Sub-Nanosecond Pulse Ouput

High-peak-power all fiberized fiber lasers are of great importance for their practical applications in laser material processing, remote sensing and SC generation.This thesis focuses on research on two kinds of all fiberized fiber laser technologies, one is the LD based Master Oscillator Power Amplifier (MOPA) all fiberized laser, the other is SBS based high repetition rate sub-nanosecond all fiberized Yb fiber laser.The LD based MOPA all fiberized laser was researched firstly.The seed laser was a laser diode (LD) with 4ns pulse width,100 kHz repetition rate and 100 μW output power. In the first stage of amplification we adopted the pulse pump technology in order to suppress the amplified spontaneous emission(ASE), and we can realize one stage amplification of 37.8 dB with ASE spectrum 50 dB below the laser peak spectrum. After two other continuous pump amplification, we realized all fiberized fiber laser with 4ns pulse width,100 kHz repetition rate with 38 kW peak power output.We then researched the all fiberized SBS based high repetition rate sub-nanosecond Yb fiber laser and its application for supercontinuum generation. The high repetition rate ns laser pulses were produced from a fiber Bragg grating (FBG) constructed fiber laser cavity consisting of a piece of double cladding Yb fiber as the gain medium and a short piece of Bi/Cr doped fiber as a saturable absorber (SA). By optimizing the fiber length of the Bi/Cr doped fiber and the reflectivity of the FBG, the Q-switching state of the fiber laser can be changed from SA Q-switched state to SBS Q-switched state. The fiber laser had an average laser power output of 1.2 W at 1064 nm with pulse repetition rate of about 80 kHz, almost four times of the state-of-the-art. The pulse duration was about Ins with peak power of about 15 kW. After one stage of amplification, the laser power was raised to about 3W and was used to pump a 20-m-long photonic crystal fiber (PCF). Supercontiuum (SC) laser output was obtained with average power up to 1.24W and spectrum spanning from 550 nm to 2200 nm.