Reflectarray as a 2D Dispersive Optic for Dispersive THz Spectroscopy

For research, the development of a low-cost and lightweight spectroscopy system is of interest. Spectroscopy is the investigation of the absorption and the emission of electromagnetic waves by a material, where the resulting spectrum represents the intensity of the wave as a function of frequency. In this article, we demonstrate the performance of a simple principle of THz spectroscopy, and we show that the data analysis does not require complex signal processing or complex calibration. Combining a CMOS THz camera with a reflectarray enables spatial-spectral mapping of incident THz radiation with an average spatial frequency resolution of about 5 GHz per pixel for a pixel size of 80x80 $\mu m^{2}$ of the receiver, comprising of a 2D array of 32x32 CMOS detector pixels.