PROJECT TITLE :

First In-Field Application of a Full Photonic Local Oscillator to Terahertz Astronomy

ABSTRACT:

This letter reports on our recent enhancements in photomixing technology for the realization of a photonic native oscillator (LO) at one.05 THz for the Atacama Pathfinder Experiment (APEX) radio telescope. Experiments with state-of-the-art photomixers, operated at space temperature and in cryogenic setting demonstrate successful operation of an astronomical heterodyne receiver at 1050 GHz with a superconductor–insulator–superconductor (SIS) mixer. The system noise temperature of the heterodyne receiver pumped by the photonic LO was a minimum of as low as that using a typical solid-state LO in the same receiver system. An optical comb generator served as a relative frequency reference to that both lasers were part-locked. Beneath the phase lock condition, the 3 dB linewidth of the THz signal was below 3 kHz and could be continuously tuned within a vary of five hundred MHz—the tunability of the system make up my mind by the photomixer antenna resonance bandwidth, which was roughly 200 GHz. We have a tendency to installed the laser system within the telescope pedestal, from there, the frequency-stabilized laser signal, was fed into the photomixer, installed within the Nasmyth cabin of the telescope, through a 20 meters long single-mode fiber optic.