Basis for Picosecond Structure in Mode-Locked Laser Pulses

Abstract

In careful experimental measurements of mode-locked laser pulses, using nonlinear media, a number of workers have found evidence for what appear to be coexisting subpicosecond pulses, and pulses in the range of 10–40 psec. In this letter we describe a model of a light pulse in which a Gaussian random-radiation field (i.e., a thermal field) of limited spectral extent is modulated by a temporal pulse envelope, and we show that predictions based on such a model are in excellent detailed agreement with published experimental results. We also consider the case of a pulse of linearly chirped radiation, and show that a clear distinction can be made between this case and a pulse of Gaussian random radiation.