Second-harmonic generation in bulk and waveguided LiTaO₃ with domain inversion induced by electron beam scanning

Bulk quasi-phase-matched frequency doubling experiments are reported for a lithium tantalate crystal which was periodically poled through its 0.5 mm thickness by electron beam scanning. The measured phase-matching bandwidth of 1 nm for the 2-mm-long domain inverted section was close to the theoretical value of 0.4 nm, although the conversion efficiency was lower than theoretically expected. Chemical etching revealed domain duty-cycle variations and incomplete inversions which are likely to have caused the lower conversion efficiency. Frequency doubling in waveguides fabricated in this material produced a normalized conversion efficiency of 290%/W cm2 and a phase matching bandwidth of 0.3 nm for a 1-mm-long domain inverted region.