Increasing the EFISH sensitivity by an optical parametric amplifier

An optical parametric amplifier (OPA) is used to increase the sensitivity of the electric field-induced second-harmonic generation (EFISH) technique. The third harmonic of a picosecond Nd:YAG laser at 355 nm is used as a pumping beam to amplify the EFISH signal at 532 nm in a Type I BBO crystal. An amplification by a factor of 60 is demonstrated by the test measurements, proving the feasibility of the EFISH-OPA approach. Further increase of the amplification is possible by increasing the 355 nm pumping energy.