New Wavelength Lasers Based On Nd:LYSO Crystal

Laser gain medium is the key part of a laser. The study of gain medium in the laser cavity resonator occupies most of the work in solid state laser researches. The absorption and emission spectra of the laser gain medium are very important because they have a tremendous impact on the output performances of the laser. Generally, the peak wavelengths of the absorption and emission spectra rely on the doped rare earth ions whereas the widths of the spectra have close relation to the characteristics of the gain medium. In simple terms, the gain medium absorption or emission spectral widths would be different because of the difference of crystal lattice structures and doped rare earth ion positions.In recent years, disordered crystals have drawn an enormous attention because they provide broad absorption and emission spectra which can be very useful in the laser performances. Broad absorption spectrum favorites the choosing of pump sources and broad emission spectrum is essential in some specific areas.Among all the disordered crystals, silicate materials are unique and possess merits over other materials. Silicate material allows high doping ion concentration and provides physical and chemical stability which can be used as the gain medium in lasers. Lutetium yttrium oxyorthosilicate ((Nd0.005Lu0.4975Y0.4975)2SiO5, LYSO) is one of silicate materials. In this thesis, we research the properties of the absorption and emission spectra of Nd3+doped LYSO crystal and study the continuous wave and Q-switched laser performances of this crystal under the pumping of a fiber coupled laser diode. The main contents are as follows:1. The 1059.5 nm continuous wave and actively Q-switched laser performances of b-cut Nd:LYSO crystal as the laser gain medium were demonstrated. We employed the 808 nm LD as the pump source and the acousto-optic modulator as the Q-switcher. The influences of different resonant cavities and pump coupling fibers on the continuous wave laser performances including laser thresholds and output powers were studied. By using the Q-switcher, the Q-switched laser was achieved and we studied the average output powers, laser pulse widths. The pulse energy and peak power were calculated.2. The input and output relationships of continuous wave and actively Q-switched 1359.5 nm Nd:LYSO laser under LD pumping was studied. We investigated the continuous-wave laser output performances under different resonating cavities. By inserting the acousto-optic modulator as the Q-switcher we achieved the actively Q-switched laser operation. The average output powers, laser pulse widths were studied. The pulse energy and peak power are calculated. The main innovations of this thesis are as follows:1. The 1059.5 nm continuous-wave and Q-switched laser performances of Nd:LYSO crystal are obtained for the first time.2. The Nd:LYSO crystal laser emitting at 1359.5 nm was achieved for the first time. The continuous-wave and actively Q-switched properties of the laser are studied.