Physical Approaches to Designing a Two-Cascade Terahertz Laser Generating Difference-Frequency Radiation in a Nonlinear Optical ZnGeP{sub 2} Crystal

An optical layout of a two-cascade frequency converter of the mid-IR laser radiation into the terahertz (THz) radiation is proposed. In the first stage it is assumed to convert the Tm:YLF-laser frequency in a Cr{sup +2}:ZnSe polycrystal into the radiation with the wavelength ~2–3 μm. The second cascade can be presented as a parametric conversion of the frequencies of two laser sources operating in the ~2–3 μm range into the THz radiation via the difference-frequency mixing in a nonlinear optical ZnGeP{sub 2} crystal. The estimates of the terahertz output signal are reported.