Phase sensitive array detection with polarisation modulated differential sensing

It has recently been shown that polarisation modulated differential surface plasmon sensing can be used to monitor refractive index changes of approximately 2 × 10−7 refractive index units. The information for these measurements is carried by a small-modulated light component and a relatively large constant background signal. These measurements have, hitherto, only been carried out as point measurements. In this paper we demonstrate that multipoint measurements can be obtained using a CMOS camera array that directly detects the amplitude and phase of the oscillating component of the light. The effectiveness of the parallel measurement is demonstrated by monitoring the changes in a waveguide mode as the refractive index of the dielectric layer is changed by exposure to ultraviolet radiation. This paper demonstrates the potential of phase sensitive CMOS detection in applications where spatially resolved differential imaging is required, especially in the field of chemical and biological sensing.