In graduate school at the University of New South Wales I began working on polarimetry as applied to exoplanets in particular (with some collaborative applications to debris disks, intrinsic stellar polarisation, and the interstellar medium). Polarimetry is a great resource for exoplanets because it naturally enhances the contrast with their host stars (stars typically do not produce a net polarisation), provides complementary information about atmospheric scattering to other characterisation techniques, and provides orbital information.
Along with atmospheric effects from Rayleigh scattering or scattering aerosols, polarimetry could be used to detect liquid oceans or to distinguish between biosignatures and their imposters.
In 2014, the Polarimetry and Atmospheres group, led by Jeremy Bailey, at UNSW (of which I am a part) commissioned the most precise polarimeter currently available in the world. The polarimeter--lovingly named HiPPI (High Precision Polarimetric Instrument)--is modular, compact, and inexpensive with parts particularly sensitive to the blue polarised light of Rayleigh scattering. Using the polarimeter we have measured the polarised light from several exoplanet systems. My paper on a confident non-detection for polarised light from HD 189733b is available at this link. We are currently finishing observations for the WASP 18 system. These observations were also used to validate the polarimetric capabilities of our atmospheric modelling software, VSTAR (Versatile Software for the Transfer of Atmospheric Radiation).
At the Virtual Planetary Laboratory I am hoping to extend polarised light theory towards smaller worlds, extending from early work on detectability to a modern assessment of the practicality of using polarimetry to characterise terrestrials, distinguish super Earths, and perhaps detect biosignatures.