Two Photon Pumped Bulk Semiconductor Laser for the Generation of Picosecond Pulses

Abstract

Recently considerable attention has been devoted to optically pumped bulk semiconductor lasers. The primary motivation has been to obtain high peak power, which has been a main drawback of diode lasers due to their small active volume confined to the junction region. Single photon longitudinal pumping of the bulk semiconductor platelets have yielded tunable semiconductor lasers with pulse widths of ~4–6 picoseconds [1,2], however, peak powers did not exceed a few tens of watts. This performance is difficult to improve through single photon longitudinal pumping due to poor heat dissipation and low thermal conductivity, and any further increase in the power of pump laser leads to the destruction of the medium. We underscore that the single photon longitudinal pumping, which is adapted from a dye laser system can not be easily adopted for optically pumped semiconductor lasers for the following two reasons: 1) heat dissipation does not present any problem in a dye system because it is flowing, 2)the absorption coefficient, a factor which is fixed in a semiconductor can be manipulated by adjusting the concentration of the dye. Thin platelets, of the order of l0μm, have been used for semiconductor lasers, which is quite thick compared to an absorption depth of 1μm. Consequently the gain medium has a nonuniform population inversion.

On leave from Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, PRC.

On leave from Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, PFC.

On leave from Peking Research Institute of Materials and Technology, Peking, PRC.