Design and Analysis of a Deep UV Laser based on Ce³⁺: LiSrAIF₆

Abstract

Ce³⁺:LiSrAlF₆ (Ce:LiSAF) has been demonstrated to amplify light between the wavelengths of 285 and 297 mn by several groups. A source in this region of the ultraviolet is attractive for biophysics, physical chemistry, and ultra-strong-field physics, particularly if femtosecond operation can be achieved. Motivated by the successful operation of Kerr-Lens mode-locked (KLM) Cr³⁺:LiSAF oscillators in the red and near infrared, we have undertaken the analysis and design of a KLM oscillator and amplifier system based on Ce:LiSAF. Since Ce:LiSAF has an absorption band centered near 260 nm, a limited selection of pump sources is available. A comparison of those sources is presented. The two-photon absorption band edge of the colquiriite host can be estimated to be in the region of 105 – 130 nm, a range based on the absorption properties of its constituents. This suggests minimal two-photon absorption of the UV radiation by the host. As a result, the second order index of refraction (n₂) should be positive so that conventional KLM operation of a laser cavity will be possible. In addition, since the bandwidth is capable of supporting sub-100 femtosecond pulses, the material is a promising gain medium for amplification to high peak powers. Accordingly, an outline of the development of a terawatt class 290 nm, sub 100 fs laser system is given.