Ultra-Wideband Photonic Radiometer for Submillimeter Wavelength Remote Sensing

Abstract

The sub-mm wave region of the electromagnetic spectrum, especially the span of 70 GHz centered on the 556.9 GHz H2O water line, offers a rich harvest of highly diagnostic volatile species that provide powerful insights into a planetary body's origins, thermal history, and conditions for habitability. Previous spaceborne Heterodyne Sub-mm Wave Spectrometers (HSWS) process a small fraction of their capable bandwidth at a given moment. The design of each spectrometer channel also depends on a priori knowledge of observable spectral features. Expanding this capability using traditional electronic hardware substantially increases the mass and power consumption of the instrument, limiting its use for CubeSat and SmallSat platforms. Microwave Photonic Integrated Circuits (PIC) is an enabling technology to fabricate an ultra-wideband, high-resolution, sub-mm wave spectrometer that could simultaneously process the receiver's entire bandwidth at a reduced size, weight, and power consumption (SWaP). Through the development of a test platform to combine commercial-off-the-shelf (COTS) and PIC components, we demonstrate the feasibility of a PIC spectrometer.