Picosecond E-field CARS; A diagnostic technique for measurement of electric field in pulsed plasmas

Abstract

Proof-of-concept measurements are presented demonstrating an optical four wave mixing based electric field diagnostic with sub-nsec temporal resolution. The second harmonic output from an ~30 psec pulse duration mode-locked, cavity dumped Nd:YAG laser is input to an H2 stimulated Raman shifting (SRS) cell, which produces the required Stokes beam which is automatically overlapped in space and time with the pump. Re-focusing the collinear pump/Stokes beam into an H2 static cell with applied sub-breakdown DC electric field produces an IR beam at 2.406 microns, corresponding to the H2 J=1 fundamental vibrational frequency. Sensitivity of .8 kV/cm is demonstrated at pressures as low as 100 Torr.