Speaker
Description
Like intensity interferometry, optical heterodyne interferometry offers a compelling and scalable alternative to direct interferometry for hectometric/kilometric baselines. However, it is well known that direct detection of light outcompetes coherent heterodyne detection in terms of signal-to-noise ratio at optical wavelengths, not only because of the narrow (<100 GHz) electronic bandwidth of photodetectors bandwidth, but also because of the shot noise of the optical reference. The mass production of high-quality, cost-effective fiber telecom components (detectors, modulators, WDMs) in the J+H band (soon also K band), combined with the rise of large-bandwidth ultrafast lasers, may open a new detection scheme for heterodyne interferometry. In this talk, we present a multiplexing approach to parallelize heterodyne detection in an all-fiber, telecom-based system using a broadband swept-source from an ultrafast laser as a local oscillator. To support its feasibility, we present a first laboratory proof of concept achieving a signal-to-noise ratio likely sufficient for observing the brightest H-band stars with ~1 m² collecting area telescopes and short integration times (<100 ms). This provides a basis for discussing the shared multiplexing challenges common to both intensity and amplitude interferometry, and opens the possibility of sharing photonics technologies to compete with direct detection.
