A theoretical analysis of optical-to-THz conversion efficiency via optical rectification

A theoretical analysis of an ultra-short pulse converted to Terahertz radiation via optical rectification in nonlinear optical crystal is presented here; several factors that affect optical-to-THz conversion efficiencies are discussed; pulse durations affect the conversion efficiency effectively: when crystal length is equal to the optimal crystal length l (c), optical-to-THz conversion efficiency is the highest, but for the periodically-inverted electro-optic crystals, conversion efficiency is almost proportional to the crystal length when absorption can be neglected. Taking account of the absorption of crystals, effective length of crystal is L (eff)=0.63/alpha, there is no apparent increase of conversion efficiency and the conversion efficiency approaches to a constant eventually when the crystal length is increased.