Comparative analysis of tunable terahertz generation in DAST and BNA using difference frequency mixing

Abstract

In this work, numerical analysis has been carried out to study the tunable terahertz (THz) generation in DAST (4N, N-dimethylamino-4′-N′-methyl-stilbazoliumtoyslate) and BNA (N-Benzyl-2-Methyl-4-Nitroanaline) using difference frequency generation (DFG) between the two optical beams, which can be generated from dual signal wavelength optical parametric oscillator (DSW-OPO) pumped by a single suitable laser. By varying the input wavelengths in the range 1,300–1,450 nm we obtained 0.1–23 THz tunable THz frequency in DAST. For BNA crystal, we varied the input wavelength in the range 750–900 nm to get widely tunable output ranging from sub- THz to 30 THz. The output THz power at the 0.47 THz was 0.02 and 0.07 W in DAST and BNA respectively. Thus, BNA is considered to be more suitable for sub-THz generation. At higher THz frequencies DAST provides greater output power and hence DAST and BNA supplement the dips in THz power spectrum of each other. It was also found that the THz power was saturated beyond 36 and 45 mm at 2.14 and 1.67 THz in BNA while, at the same frequencies the THz power was saturated at 4 and 2 mm length of DAST crystal.