Widely tunable and monochromatic terahertz difference frequency generation with organic crystal DSTMSPengxiang Liu, Degang Xu, Yin Li, Xinyuan Zhang, Yuye Wang, Jianquan Yao and Yicheng WuEPL, 106 6 (2014) 60001DOI: https://doi.org/10.1209/0295-5075/106/60001