Methods and systems for sensing

Abstract

A sensing device for sensing a substance includes a photonics integrated circuit having a resonator element that supports two different radiation modes, e.g. radiation modes of different polarisation, at a predetermined resonance wavelength. The resonator element is configured to convert a phase change or amplitude change experienced by the two different radiation modes upon formation of a layer of receptor molecules onto a sensing surface of the device into a resonance wavelength shift for the two different radiation modes. The sensing device also includes a detection unit arranged to detect the resonance wavelength shift for the two different radiation modes. The detection unit includes a processor that is configured to derive from the detected resonance wavelength shifts for the two different radiation modes, a layer thickness and refractive index of the layer of receptor molecules.