Generation of Harmonics of Terahertz Radiation in Paraelectrics in a Wide Temperature Range

It is investigated theoretically the generation of higher electromagnetic harmonics of the lower part of terahertz range in nonlinear paraelectrics like SrTiO₃. The efficient generation of harmonics is possible when the bias electric field is applied to the crystal to get the quadratic nonlinearity. The initial focusing of the pump first harmonic makes possible to realize the selective generation of proper higher harmonics. In the paraelectric SrTiO₃ the efficient harmonic generation occurs in the wide range of temperatures 50 - 200 K.