Delay Effect in Laser Amplifiers

In the Stanford Free Electron Laser it is necessary t o desynchronize the electron pulses from the accelerator with the light pulses. This effect is a major complication in the data analysis of the FEL. In this presentation, the desynchronism effect is considered for a Laser amplifier. The equations are substantially simpler than the FEL, and most of the results can be obtained analytically. Both the gain (linear) and saturation (nonlinear) regimes are investigated. BASIC MODEL Excited two level atoms are injected transversly into a channel in which the light builds up. The gain bandwidth of such an amplifier is caused by the transit time of the atoms, which is the same broadening mechanism as in the FEL in the 'cold beam' limit. Light pulse moving Gain Channel excited atoms moving at a scissor velocity v<c. Gun Fig. 1. Light propagating down a channel is amplified by scanned atomic beam. The atoms are injected in the excited state and move transversely t o the channel. The gain bandwidth of this amplifier is determined by the transit-time to the atoms in the channel. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983110