Novel real-time monitoring technique of the all-optical poling process

摘要

All-optical poling technique permits purely optical orientation of molecules. The experiment consists of two steps: the writing (so called "seeding") period and the readout one. In the seeding phase two beams, the fundamental one (ω) and its second harmonic (SH, 2ω) illuminate the sample and print in the medium the second order x~((2)) susceptibility grating with a periodicity satisfying the condition of phase matching for SH generation. In the readout period only the fundamental beam irradiates the sample and the second harmonic generation is observed at the sample output. Efficient all-optical poling requires optimisation of the seeding beam intensities and their relative phase difference. We propose a novel technique for non-perturbative monitoring of the all-optical poling process and the easy method of orienting molecules without any necessity of taking into account the phase difference between seeding beams.