Phase conjugation by wave-mixing interactions in solid-state laser gain media [French]

摘要

The heat load deposited in solid-state laser medium leads to thermally induced aberrations. This undesirable effect causes wavefront distorsions and reduces the brightness of lasers. Phase-distorsion correction of an optical wave propagating in laser media is thus a crucial problem that must be taken into account in solid-state laser sources. Indeed, many applications require a high-spatial-quality, diffraction-limited output beam. An approach offering great potential to solve this problem involves nonlinear optical phase conjugation. Phase conjugation can be obtained with degenerate wave mixing in the laser medium itself by gain saturation. The use of solid-state laser amplifiers for such operation presents very attractive features including the automatic matching of the nonlinearity with the laser wavelength, a fast response time and a high efficiency of the nonlinear process due to the laser amplification of all interacting beams. In as much as gain saturation is inherent in all tenporal regimes, phase conjugation in inverted media can be performed in both pulsed and cw regimes. This nonlinear mechanism is theoretically analyzed and experimentally demonstrated in flash-lamp primped Nd:YAG amplifiers and in a compact diode-pumped Nd:YVO4 amplifier in the nanosecond pulsed regime. Efficient continuous wave operation is also demonstrated in a Nd:YVO4 amplifier pumped by a cw Ti:sapphire laser. Applications to dynamic holography and correction of aberrated wavefronts propagating in laser media, are presented. Finally, it is shown that saturable gain media can be used as efficient phase conjugate mirrors for all-solid-state high beam quality laser sources. [References: 80]