Ld Pumped Microchip Lasers Study

LD-pumped microchip lasers combine many advantages such as compactness, reliability, high beam quality, high efficiency and long lifetime. They are of great interest in the field of laser radar, biomedicine, micro-mechanism, range finder, remote sensing, pollution detection and space optical communication, etc. They have been a hot point in laser technology and devices.To get stable and controllable laser pulses with short duration and high repetition rate for a seed source in MOPA system, the dissertation focuses on two important technology to generate short pulses: passive Q-switching and gain-switching. The theory analyses, simulation calculations, experiment researches and parameters optimization have been made. The following results were achieved in the article.A signal generator based on NE555 and 74LS123 was designed, which will be used as LD modulation signal. By choosing the capacitance and tune the resistance, frequency between 15Hz to 277KHz and pulse width between 65ns~l.lms were easily gained.During the solution process of the rate equations of Cr~4+ doped passive Q-switched lasers, many parameters of resonance cavity and saturable absorber are integrated into two synthesis parameters. The relationship of and the energy, peak power and duration of Q-switched laser pulses with the synthesis parameters are calculated.Using pre-pumping technique, the highly stable Q-switched laser pulses with repetition rate from 15Hz to 25kHz was acquired in a Cr~4+,Nd~3+:YAG microchip laser. The experimental results accord well with the theory calculations.In the dissertation, the gain-switching model of four-level lasers is established. For the first time, the variation of the laser output characteristics with LD pump direct current, pump pulse current and pump pulse width was calculated by numerically solving the model. Furthermore the optimal LD pump parameters were acquired aiming to get maximum peak power and minimum pulse duration.A monolithic small Nd~3+:YVO4 gain-switched laser was developed. Stable laser pulses with repetition rate varied in a large range of lHz-25kHz were acquired with homemade modulation signal generator.