Subterahertz noise signal generation using a photodetector and wavelength-sliced optical noise signals for spectroscopic measurements

Abstract

We present a photonic technique for generating a subterahertz time-continuous noise signal, which provides not only fine resolution and a potential for broadband measurements but also a higher output power resulting in high signal to noise ratio for the spectroscopy measurement. To increase the output noise power at subterahertz frequencies, the optical noise is sliced with the arrayed waveguide gratings (AWGs), resulting in the power level of -126.1 dBm/Hz at 350 GHz, which is approximately 17 dB higher than that without the AWGs. Using the implemented subterahertz noise signal source, we demonstrate a simple spectroscopic measurement of the H2O absorption line at around 380 GHz.