Speaker
Description
The existence of natural lasing lines in the environment of Eta Carinae is predicted by a multitude of spectral observations. Could these lines be produced by "random lasers", where traditional cavities don't exist but light feedback is supplied by scattering of the photons within the medium itself? Different emission lines in the spectrum of Eta Carinae between 960 nm and 1.7 micrometers are thought to operate in lasing mode, suspected either by the high brightness of the suspicious line itself, or by other lines of the same radiation cycle. Proof of the laser action, however, still needs to be accomplished.
One part of the IC4Stars project is to observe these emission lines with an intensity interferometer, and by that verify their origin. To support high quantum efficiencies over the entire near-infrared region, high time-resolution (<30 ps) superconducting nanowire single photon detectors (SNSPDs) are characterized and prepared for on-site observations. As a photon-correlation measurement in a single telescope can distinguish thermal and coherent emission by the existence or non-existence of photon bunching, the partially or fully coherent nature of these lines can be tested. In the case of incoherent emission, the predicted extremely narrow linewidths can be measured by their signature in the temporal correlation function, as in these cases the nanosecond-scale coherence times can be directly observed in the profile of the correlation peak.
In this contribution we will present the challenges of such a correlation measurement - signal-to-noise estimations, requirements on optical filtering and telescopes - as well as the characterization process of the SNSPDs, including time-resolution and correlation measurements in the lab at wavelengths between 780 and 1560 nm.
