Small-size terahertz spectrometer using the second harmonic of a femtosecond fiber laser

Possible implementations of a small-size terahertz spectrometer with a subpicosecond resolution on the basis of a femtosecond fiber laser are considered. An experimental sample of a spectrometer is fabricated. This spectrometer employs the method of optical rectification in a ZnTe nonlinear crystal and the Dember (photodiffusion) effect on the InAs semiconductor surface to generate terahertz radiation and the polarization-optical method to detect radiation. System operation is demonstrated by an example of measuring the terahertz absorption spectrum of water and determining the refractive index of the β -BBO crystal. The basic spectrometer parameters are found: spectral range, spectral resolution, and dynamic range of the terahertz spectrum amplitude.