efficient generation 1.5thz pulses using dasc/gaas and dasb/gaas multilayer structures via difference frequency generation 1.5 µm femtosecond laser pulses

We present a study of high efficient terahertz (thz) wave generation in dasb/gaas, dasc/gaas, and dast/gaas multilayer structures at 1.5thz via difference frequency generation (dfg) process with 1.5µm femtosecond laser pulses. we also compare the conversion efficiency in proposed structures with dasb/sio2, dasc/sio2, and dast/sio2 multilayer structures and bulk crystals dasb, dasc, and dast. these structures compensate for phase mismatching in bulk crystals dasb, dasc, and dast and increase conversion efficiency from 10^-5 in bulk organic crystals up to 10^-3 in multilayer structures. we show that dasc/gaas is the best structure to generate 1.5thz waves.