SPECTRAL CHANGES OF STIMULATED RAMAN-SCATTERING FROM MODULATED WATER CYLINDER

The spectral changes of stimulated Raman scattering (SRS) from a micro meter-sized sinusoidally modulated water jet (radius, similar to 14.5 mu m) have been observed. The pumping pulses of a frequency-doubled Q- switched Nd:YAG laser were synchronized to the modulation wave on the water jet. Before conducting SRS experiments, we measured the modulati on amplitudes of the water jet from the diffraction patterns. The spec tral changes of SRS exhibited the peak's shifts, the narrowing down of the SRS spectral range, and the reduction of the SRS peak. From the e stimation of the mode orders of the SRS peaks with the cylinder modes, we found that the cylinder modes are not sufficient to explain the ob served SRS peaks at small modulation amplitude, which are thought to b e caused by the appearance of new modes in the modulated jet. We have interpreted the spectral changes as the reduction of the effective qua lity factor in the modulated cylinder. (C) 1997 Optical Society of Ame rica.