Terahertz emission from coherent phonons in lithium ternary chalcopyrite crystals illuminated by 1560 nm femtosecond laser pulses

摘要

We have investigated terahertz (THz) emission from lithium ternary chalcopyrite crystals LiInSe_2, LiGaSe_2, LiInS_2, and LiGaS_2 that were illuminated by 1560nm femtosecond pump laser pulses. Monocyclic THz emission caused by nonlinear optical effects was initially observed in all the illuminated crystals. Narrow-band THz emission from the coherent phonons were observed in LiInSe_2 (2.87THz) and LiGaSe2 (2.60 and 3.45 THz). These phonon modes were most likely caused by impulsive stimulated Raman scattering.