All Fiberized Linearly Polarized Pulsed Yb Fiber Laser With High Repetition Rate

High power pulsed fiber lasers are finding a wide variety of application in material processing, laser radar, laser medical treatment and nonlinear frequency conversion, etc., are becoming one of the main concerns in the laser photoelectron technique field, because of their advantages such as good beam quality, good thermal dissipation, high efficiency, compactness and reduced weight. MOPA structured pulsed fiber lasers, whose output pulse characteristics can be controlled by laser seeder, are suitable for all-fiberized structured design. They can output a high power, short time duration and high beam quality laser and have become the research hotpot. As many nonlinear frequency conversion applications require polarization maintain operation, linearly polarized pulsed fiber lasers draw a lot of attentions in recent years. In this thesis, the main work is the research of all-fiberized MOPA structured linearly polarized pulsed Yb fiber laser with high repetition rate. The thesis is composed of the following research work:pulsed laser seeder based on directly modulated laser diode (LD) and MOPA structured linearly polarized pulsed Yb fiber laser with high repetition rate.Pulsed laser seeder based on directly modulated laser diode (LD) is demonstrated. Design an all-digital pulsed fiber laser direct-electrical driver system based on FPGA controller, which is composed of FPGA control circuit, LD protection circuit, temperature controller, LD pulse driver and PC communication modules. Using this compact high-speed electric driver to directly drive a laser diode operating at 1064 nm, a near diffraction-limited linearly polarized laser output at 1064 nm is achieved with a tunable repetition rate ranging from 5 kHz to 10 MHz,a pulse duration between 20 ns and 200 ns, a great polarization extinction ratio and a beam quality factor close to 1, and can control the LD working temperature stably within the range from 15°to 35°with the step of 0.1°.MOPA structured linearly polarized pulsed Yb fiber laser with high repetition rate is demonstrated. In the base of the pulsed laser seeder based on directly modulated laser diode (LD), using a polarization-maintaining (PM) large mode area(LMA) Yb-doped double-cladding fiber as the gain medium, developed an all-fiberized MOPA structured linearly polarized pulsed Yb fiber laser with high repetition rate. The pulsed fiber laser keeps the good qualities of the laser seeder and generates a linearly polarized laser at 1064 nm with a tunable repetition rate ranging from 5 kHz to 10 MHz and pulse duration between 20 ns and 200 ns. Under the repetition rate of 200 kHz and pulse duration time of 100 ns, the pulsed fiber laser emittes a near diffraction-limited linearly polarized pulse laser output with an average power of 800 mW, a polarization extinction ratio greater than 25 dB and a beam quality factor close to 1. It can be served as a seeder of other high power linearly polarized fiber laser.