Stimulated Raman scattering and lasing in micrometer-sized cylindrical liquid jets: time and spectral dependence

Publisher Website
Google Scholar
Abstract
Stimulated Raman scattering (SRS) in micrometer-sized water and carbon tetrachloride liquid cylinders irradiated with a pulsed frequency-doubled Nd:YAG laser (pulse length 8 ns, peak intensity ≈4 GW/cm2) have been observed. As was found previously for spherical droplets, SRS is supported by natural cavity mode resonances of the cylinder. For water cylinders SRS spectra consist of quasi-periodic peaks within the spontaneous Raman band, and the separation of the peaks suggests that the dominant emission is supported by resonances of a single mode order. As many as 14 orders of Stokes shifts are observed in carbon tetrachloride cylinders. SRS is delayed (∼6 ns) with respect to elastic scattering and is suppressed by the addition of a small amount of absorptive material to the liquid. Measurement of SRS light scattered perpendicular to the cylinder axis shows it to have the same time and spectral dependence (1) in the region of the pump laser beam for perpendicular and nonperpendicular incidence and (2) in regions of the cylinder located at least 0.5 cm along the cylinder axis from the irradiated portion. Lasing has been observed in water cylinders doped with Rhodamine 6G dye, and spectral measurements suggest that, like SRS, lasing also is supported by resonances.