Performance Limits of THz Dispersive Spectroscopes Employing Super-Resolution Imaging

The performance of terahertz (THz) dispersive spectroscopes is limited in spectral resolution and frequency accuracy due to a finite pixel count. This article demonstrates that increasing the synthetic effective pixel count by exploiting super-resolution (SR) imaging results in improved performance. To this end, we investigated the performance of a CMOS camera-based THz dispersive spectroscope using SR imaging. From 0.75–0.9 THz, average spectral resolution improved from 76 GHz to 34.2 GHz (about a factor of two), while the average frequency accuracy enhanced from 30 GHz to 1.65 GHz. Further to providing enhanced spectral resolution and frequency accuracy, our results provide an insight into the fundamental performance limits. For low-resolution (LR) imaging, the finite pixel count sets the spectral resolution limit, and for SR imaging, the camera angular resolution defines the limiting factor. For this reason, SR imaging generally improves the spectral resolution at least by a factor of two. Pixel count and noise fluctuation limit the frequency accuracy using LR and SR imaging, respectively.