Pg. Kazansky et V. Pruneri, ELECTRICALLY STIMULATED LIGHT-INDUCED 2ND-HARMONIC GENERATION IN GLASS - EVIDENCE OF COHERENT PHOTOCONDUCTIVITY, Physical review letters, 78(15), 1997, pp. 2956-2959
A strong electrostatic field applied to glass is spatially modulated b
y intense light at frequencies omega and 2 omega. The phenomenon is ex
plained in terms of photoconductivity being dependent on the relative
phase of the light fields at different frequencies.