13fs Frequency-Resolved Optical Gating Measurements with Thin Poled Nonlinear Polymers

Abstract

We use the technique of Frequency Resolved Optical Gating (FROG) [1] to measure the amplitude and phase of an ultrashort pulse.[2] Although there are several variations of the FROG technique which use different nonlinear processes, second harmonic generation (SHG) FROG is particularly well suited for measuring unamplified nJ pulses directly from a modelocked Ti:sapphire oscillator, since SHG produces a much larger signal than the higher order nonlinear processes. Experimentally, SHG FROG is similar to a second-order intensity autocorrelation, except that the second harmonic spectrum is measured as a function of time.