Enhanced second-harmonic generation by use of the photonic effect in a ferroelectric smectic C* liquid crystal.

Special phase matching of second-harmonic generation (SHG) by use of the photonic effect was experimentally confirmed for an obliquely propagating fundamental beam in the helical smectic C>(*) liquid-crystal phase, as suggested by Belyakov [JETP Lett. 70, 811 (1999)]. The enhancement of SHG occurs when the second-harmonic wave is close to a photonic bandgap (half-pitch band) and consequently the fundamental wave is close to another photonic bandgap (full-pitch band). The enhanced signal was observed from both the transmitted and the reflected directions and was compared with our recently developed simulation.