High Repetition Rate and Mode-Locked Phosphate Glass Laser

摘要

High repetition rate operation of a picosecond glass laser up to 10 Hz was achieved by using a new kind of phosphate glass. The pulse duration is 24 ps, the spectral width is 0.84 A and the total energy of the pulse train is 6 mJ. The key to the operation of glass materials at high repetition rates lies not only in an improvement of their thermal conductivity, but also in an avoidance or elimination of the undesired optical pumping induced thermal effects, such as the optical path change due to change in the index of refraction with temperature, and the linear expansion coefficient. For silicate glass, both are positive. The new-type of phosphate glass adopted in our laboratory exhibits negative and positive linear expansion coefficient behavior, so that changes in the optical path resulting from both of them can be compensated by each other. As a result, such a change can reach a minimum value each time when light travels back and forth in a laser cavity.