Title

Two-beam coupling in liquids via stimulated Rayleigh-wing scattering

Abstract

Transient energy transfer or two-beam coupling is demonstrated in CS 2 and other transparent Kerr liquids using frequency chirped, 17 picosecond (HW1/eM) 532 nm pulses with several polarization combinations. As the temporal delay between pulses in a standard pump-probe geometry is varied within the coherence time, the first pulse always loses energy while the second pulse gains this energy. Scattering from phase gratings can lead to coherent energy coupling only if the nonlinearity has a finite relaxation time. This two-beam coupling in Kerr media such as CS 2 is associated with stimulated Rayleigh-wing scattering (SRWS). The frequency difference needed for beam coupling can be achieved with chirped pulses or with short pulses in nonlinear materials if irradiance dependent phase shifts are being developed during the laser pulse due to self and cross-phase modulation. Here we consider the interaction between linearly chirped pulses obtained from our modelocked, Q-switched Nd:YAG laser. This leads to an energy transfer linearly proportional to irradiance, so that the signal can be observed at irradiances lower than those needed for induced phased modulation. The measurements are performed on CS 2 but the results are valid for any Kerr liquid that has a nonlinear index of refraction with a relaxation time on the order of the laser pulse width. We demonstrate that the interaction follows the polarization dependence of SRWS. The only parameters needed for the theoretical fittings are the nonlinear index n 2, its relaxation time and the linear chirp of the laser pulse. The first two are well known for CS 2 and the laser chirp is independently measured using first and second order autocorrelations.

Publication Date

12-1-1996

Publication Title

Proceedings of SPIE - The International Society for Optical Engineering

Volume

2853

Number of Pages

116-125

Document Type

Article

Personal Identifier

scopus

Socpus ID

0030360654 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0030360654

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