Experimental investigation of the spatial structure of the first Stokes component of stimulated Raman scattering

Abstract

Large amplitude low frequency (0.7-2.5 kHz) oscillations which are in phase across the minor radius have been observed in soft X-ray emission since the removal of limiters from HBTXlB Reversed Field Pinch for plasmas with small field reversal, F, at all toroidal currents. These oscillations. due to variations in electron temperature, are in antiphase with oscillations in plasma resistance and ion temperature and occur in the majority of discharges where the resistance is closest to its lowest value. Correlated magnetic oscillations indicate cyclic behaviour in the F-8 plane similar to that observed at high values of 8 on other experiments, where 0 is the pinch parameter.

High Efficiency Pulse Compression by Raman Induced Cavity Dumping

“…Beam properties of the Stokes pulses depended strongly on the set-up used. The relatively poor spatial quality of the EPICRO beam was partly due to the inhomogeneity of the pumping laser, which was transferred to the Stokes beams [12]. It also resulted from the four-wave mixing process, giving rise to the second Stokes pulse.…”

Spatio-spectral beam control in multimode diode-pumped Raman fibre lasers via intracavity filtering and Kerr cleaning

“…It is well-known that stimulated Raman scattering on molecular vibrations not only shifts the wavelength of laser radiation, but may also improve laser beam quality. Initially driven by applications such as laser fusion 1 , Raman beam cleanup (RBC) has been extensively studied since its first demonstration in 1979 2 , as it provided an effective solution for improving quality and brightness of high-power Nd:glass or excimer laser beams via Raman conversion in gaseous 2 – 6 or solid-state 7 – 9 media.…”

Mechanism of brightness enhancement in multimode LD-pumped graded-index fiber Raman lasers

“…The Raman beam cleanup (RBC) effect was first demonstrated in 1979 by Andreev et al [1], and provided an effective solution for the improvement of both quality and brightness of high-power solid-state or excimer laser beams at their Raman conversion in gaseous [1] or solid-state [2] media. This idea was further applied to Raman lasers based on a multimode fiber, in which low-quality multimode pump radiation is converted into a high-quality Stokes beam [3].…”