Integrated Photonic-based Low Noise Radiometer for Millimeter and Sub-Millimeter Applications

Millimeter-wave and THz photonic radiometers based on electro-optic upconversion represent a novel detection approach to overcome the limitations in terms of volume, size and complexity of state-of-the-art detectors based on low noise amplifiers (LNAs) and mixers. Theoretical studies have shown that room-temperature radiometers based on an efficient upconverter followed by a direct detection stage could be competitive with conventional, and even cryogenic, mixers and LNAs in the THz range. In this work we present the development of a Lithium Niobate (LN) Photonic Integrated Circuit (PIC) as part of an integrated upconversion radiometer. Two optical components: an asymmetric Mach-Zehnder interferometer (AMZI) and a Whispering Gallery Mode Resonator (WGMR) were designed, fabricated and characterized. An Extinction Ratio (ER) of 25 dB and an intrinsic quality factor of 105 were achieved for the AMZI and the WGMR, respectively. Based on the characterization results of the first PIC, a second one was designed and fabricated, where the antenna for RF signal detection has been included. Details of the antenna design are also presented here.