Efficient terahertz generation in highly nonlinear organic crystal HMB-TMS

We report on generation of strong and broadband terahertz (THz) pulses via collinearly phase-matched optical rectification of near-infrared femtosecond pulses in the organic nonlinear optical HMB-TMS (2-(4-hydroxy-3-methoxystyryl)-3-methylbenzo[d]thiazol-3-ium 2,4,6-trimethylbenzenesulfonate) single crystals which exhibit optimal molecular orientation and large macroscopic optical nonlinearity for efficient THz wave generation. Single-cycle THz pulses with a peak electric field strength of 0.66 MV/cm and a bandwidth from 0.1 to 5.4 THz are achieved from an HMB-TMS crystal with only a 2-mm clear aperture pumped by 1350 nm pulses at moderate fluences. The generated THz energy is about 1 µJ and the corresponding pump-to-THz energy conversion efficiency reaches 0.23%.United States. Office of Naval Research (N00014-13-1-0509)United States. Office of Naval Research. Defense University Research Instrumentation Program (N00014-15-1-2879)Samsung Global Research Outreach ProgramNational Research Foundation of Korea (No. 2016R1A2B4011050National Research Foundation of Korea (No. 2014R1A5A1009799)National Research Foundation of Korea (No. 2015K1A3A1A14004646)National Research Foundation of Korea (No. 2009-0093826