26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Spatial mode demultiplexing for astronomy beyond the diffraction limit

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Astronomy (ASTRO)

Speaker

John Wallis (The University of Western Australia)

Description

Super resolution techniques have achieved impressive results in fields such as microscopy and lithography where engineered sources of light can be used to beat the diffraction limit [1]. However, for astronomy the light source is set by the target object and as such to achieve super resolution a measurement must passively extract more information from each photon. One such measurement scheme that achieves this is spatial mode demultiplexing (SPADE), which measures the incoming field in a basis that is more sensitive to small separations between sources than direct imaging [2]. There have been numerous recent laboratory demonstrations of SPADE’s use to perform quantum-optimal parameter estimation in laboratory environments with narrowband thermal and coherent sources [3,4]. There is has also been a recent demonstration of the technique for photocentre measurements on sky [5]. If parameter estimation of this technique can be extended to the sources more closely resembling astronomical sources, then the technique offers great promise to scale the performance of existing and future telescopes, in some cases offering improvements of more than an order of magnitude than direct imaging.

We present experimental results that advance this technique in imaging scenarios more relevant to astronomy than existing literature. In laboratory experiments based on demultiplexing with a multi plane light converter, we show parameter estimation performance of both separation and relative brightness when imaging broadband incoherent sources separated below the diffraction limit by up to two orders of magnitude. We also show the first on-sky demonstration of binary mode sorting based hypothesis testing with this technique, in a proof-of-principle demonstration. Our results show hypothesis testing performance that outperforms theoretically ideal direct imaging for a system with an equivalent point spread function.

[1] DOI: 10.1038/s41566-024-01516-w
[2] DOI: 10.1080/00107514.2020.1736375
[3] DOI: 10.1364/OPTICAQ.505457
[4] DOI: 10.1364/OPTICA.545414
[5] DOI: 10.3847/2041-8213/ae0739