Stimulated Photon Echo Induced by Broad-Bandwidth Pulses

Optical coherent transients induced by time-delayed correlated fluctuating pulses [1–4] have received a great deal of attention in the last few years, owing to their potential as a source of sub-picosecond time resolution. In particular, the effect of field fluctuations on the intensity of stimulated photon echoes (SPE) has been studied in some detail. Two laser pulses of duration tp, with wave vectors \({\vec k_1}\) and \({\vec k_2}\), respectively, are sent into a sample of two-level atoms with a relative time delay denoted by t12. These pulses (which may or may not be correlated ) create spatial gratings in the population difference of atoms with Bragg vectors \(n\vec K = n\left( {{{\vec k}_2} - {{\vec k}_1}} \right),n = 0, \pm 1, \ldots \) These gratings are subsequently probed by a third laser pulse with a wave vector \({\vec k_3}\) which is time delayed by t23 > tp relative to the first two excitation pulses. The SPE energy Wn(t12) in the directions \({\vec k_3} \pm n\vec K\) is measured as a function of delay time t12.