High power deep ultraviolet radiation generation from short pulse laser induced electron-hole pair production in a wide bandgap semiconductor

A theoretical approach of ultraviolet radiation generation via short pulse infrared laser pulse interaction with wide bandgap semiconductor is proposed. When a high intensity infrared short pulse laser incident upon it, the valence electrons to tunnel to the conduction band by laser field and generating the electron-hole pairs. The stimulated recombination of these electron-hole pairs generates the ultraviolet radiation. The concentration of the electron-hole pairs varies inside the semiconductor slab noticeably, maximum near the surface and falls sharply away from the surface due to the nonlocal effects (energy depletion of the incident laser pulse). The gain coefficient of UV laser depends on the Fermi level position, which is a function of free carrier concentration and the gain coefficient also decreases as we move away from the surface. For overall large gain of UV radiation, the thickness of the semiconductor specimen should be kept small as the gain coefficient becomes negative deeper into the semiconductor. This proposed approach will be useful for making a UV radiation source.