Methods of spectrally pure two-frequency radiation forming for terahertz carriers generation in optical range

Abstract

One of the promising methods for generating continuous terahertz radiation is the method of photomixing, when the photoconductive material is excited by the emission of two optical continuous lasers with frequencies separated by terahertz frequencies. It should be noted that for effective photomixing the polarization, frequencies and phases of the optical beams introduced into the mixer must be constant, otherwise it is necessary to additionally use a complex system of phase synchronization. In connection with the complexity of such an implementation, variants based on the conversion of single-frequency and broadband laser radiation into two-frequency ones were investigated. The first of these is modulation and consists in the external modulation of single-frequency laser radiation in the electro-optical Mach-Zehnder modulator. The second one is broadband with the allocation of two wavelengths using two rectangular fiber Bragg gratings with a small difference in width.