Abstract

Stimulated Brillouin scattering of pulses shorter than the acoustic lifetime of the Brillouin medium is a highly transient process for which the steady-state solution of the coupled-wave equations is not necessarily valid.¹ Nevertheless, past experiments² show that high reflectivities and partial phase-conjugate fidelity can nevertheless be achieved in this regime by the cumulative addition of several pulses separated by less than the Brillouin lifetime. Here we present the results of an experimental investigation into cumulative pulse SBS thresholds, reflectivities, and phase-conjugate fidelities for high-pressure gases as a function of gas pressure, focal geometry, pulse width, and total energy in the pulse train. Phase-conjugate fidelity is carefully characterized by digitizing far- field Intensity profiles, computing relative beam radii, and drawing intensity contour plots.

© 1988 Optical Society of America