POLARSENSE · Polarimetry with spatially coherent detection for ultrasensitive detection

Polarimetry with spatially coherent detection for ultrasensitive detection

The POLARSENSE project proposed a new ground-breaking approach for the detection and quantification of optical activity that permits ultrasensitive chiral discrimination through optical means. Its objective was to set up a coherent detection method that exploited the spatial coherence of light, similarly as in double beam interferometers exploit the temporal coherence of light. Switching from temporal coherence to spatial coherence supposed a paradigm shift for the optical coherent detection technique and it allowed using a single light beam instead of having to deal with two different beams. With this new technique, two different parts of the beam will acquire different polarizations and will then recombine coherently. The formed interference pattern depends on the optical properties of the sample, and they can be recovered after an holographic analysis. This spatially coherent detection method can be implemented in a Mueller matrix polarimeter capable of detecting minute differences of polarization states associated to chiral signals. The main goal of the POLARSENSE project was to achieve an unprecedented sensitivity in detection of optical activity, a wide applicability for virtually any kind of sample and in a wide spectral range. This has been achieved with a new technique for chiral sensing that is based on snapshot circular dichroism polarimetry, which permits recovering the chiroptical properties of a sample from analysis of an interference pattern formed in polarimetric experiment with a single beam. Molecular chirality is a key area for large added value products: The pharmaceutical industry alone has worldwide sales of single enantiomer drugs of anywhere up to 410 billion Euros according to recent estimates. It is therefore not surprising that the necessity of producing enantiomerically pure compounds is now a basic tenet of the Chemical Industry. It is also a growing area for fundamental scientific research, given the unknown nature of the origins of homochirality in biological systems and the increasing number of applications of optical activity in photonics.

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