Effect of group velocity mismatch in nonlinear mixing schemes to recover ultrashort optical signals

Abstract

Frequency resolved optical gating (FROG) as a technique for the full characterization of ultrashort optical signals as complex electric fields is based upon nonlinear processes like second harmonic generation (SHG) or sum frequency generation (SFG). To determine the effect of group velocity mismatch an expression for SHG and SFG FROG traces is derived for a collinear geometry. Effects to the FROG traces like smearing and temporal shifting are predicted. With the result one can judge the errors in conventional and angle integrated FROG traces.