A Compact Immersion Grating Spectrometer with Quantum Capacitance Detectors for Space-Borne Far-IR Spectroscopy Project

<p>SPECTROMETER:&nbsp; The grating spectrometer uses a curved grating fabricated on a high resistivity silicon wafer. Light will be coupled in via a silicon immersion lens and coupling waveguide. The wafer profile, including the grating facets are defined by photolithography and deep reactive etching (DRIE) and the wafer is metallized on both sides for better light confinement (except in the regions below where the detector antennas will be placed).&nbsp; The grating both focuses and diffracts the light in the plane of the wafer to a focal arc, where the detectors are positioned. QCD DETECTOR ARRAY: The Quantum Capacitance Detector is a mesoscopic superconducting device that exploits its extreme susceptibility to the presence of quasiparticle excitations arising from pair-breaking radiation to enable background limited detection.&nbsp; QCDs have demonstrated photon noise limited performance&nbsp; at 1.5THz for optical loadings 10-20 to 10-17W.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The detector die will be placed directly on top of the spectrometer wafer and will have an array of QCDs with antennas positioned at the focusing spots of each wavelength.&nbsp; Each detector will be coupled to a superconducting resonator with a different resonant frequency to allow for frequency multiplexing with a single feedline coupling the RF signal to all resonators.&nbsp; A&nbsp; prototype with 32 spectral channels will be demonstrated</p>

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