Abstract

Since the off-axis multiple-pass cell (MPC) constructed by two mirrors with an equal curvature can provide a long optical length in small physical space they are used for various applications such as Raman conversion, absorption spectroscopy, and optical delay lines. A number of studies have been carried out to analyze the propagation characteristics of Gaussian beams in the MPC, however, the subject of those works concentrated on the lowest-order Gaussian beams.^1,2 The behavior of non-Gaussian beams such as annular beam is of great interest because intense laser beam produced from a single unstable TEA CO₂ resonator oscillator is attractive for pumping the para-H₂ Raman laser, which presently use a long master oscillator power amplifier chain of CO₂ laser. In this paper we present propagation characteristics of non-Gaussian beams in the MPC aiming at effective Raman conversion.

© 1995 IEEE