Accumulated photon echoes with incoherent light inNd3+-doped silicate glass

Abstract

Accumulated photon echoes were observed in ${\mathrm{Nd}}^{3+}$-doped silicate glass by using coherent and incoherent light, and it was theoretically and experimentally verified that the time resolution is determined not by the pulse width but by the correlation time of the excitation field. Even by using a cw laser, instead of a mode-locked laser, a subpicosecond time resolution was obtained when it was operated with a broad and smooth spectrum. The broadest output spectrum, and hence the highest time resolution, was attained when the dye laser was pumped by a mode-locked ${\mathrm{Ar}}^{+}$ laser, and their cavity lengths were mismatched by a few μm. In an experiment with a resolution time of 220 fsec, a new very fast decay was observed in the echo decay curve besides a slower decay already reported.