Nonlinear frequency conversion using common optical coatings and applications

We investigate nonlinear signal generation from a variety of optical coatings on common filters and mirrors. The prevalent signal is third harmonic generation (THG). The THG conversion efficiency of some widely available optical coatings was surprisingly high, >10^-4 with modest femtosecond laser excitation pulse energies of ∼6 nJ. In addition, we demonstrate third order interferometric autocorrelation, fifth harmonic generation, and non-collinear sum frequency generation using thin film coatings of off-the-shelf bandpass filters.