A new method of terahertz detection based on photoluminescence modulation

We present a new approach for terahertz (THz) detection that can be adapted into a less complex and cost-effective THz imaging system. Unlike conventional techniques, this approach does not require direct measurement of THz radiation and hence enables the use of standard silicon-based sensors, such as a CMOS camera, for the detection. The THz signals are inferred through measurement of changes in the photoluminescence (PL) signal induced by THz absorption in a photo-excited silicon wafer. We analyze the PL spectrum over a wavelength range from 950 to 1300nm to determine a spectral range that exhibits the largest change in the PL spectrum and thus provides optimal sensitivity. The spectral measurements show that the maximum change in PL occurs near 1140nm, which corresponds to the silicon bandgap. Based on this observation, the PL spectrum is spectrally filtered around this wavelength and is used for THz detection. Furthermore, we demonstrate that this approach can potentially be extended for THz imaging. This proposed method is easy to implement and opens the possibility of integrating THz technology with existing optical imaging systems.