An optical sensing device is provided, including a first polariser, a second polariser, wherein the first polariser and the second polariser have respective transmission axes aligned in orthogonal directions, an SPR sensor arrangement including an SPR sensing surface, the SPR sensor arrangement arranged to receive an incident light beam passed through a polariser to be reflected at the SPR sensing surface and transmitted through a second polariser to provide a transmitted light beam, a detector arrangement configured to detect the transmitted light beam, the transmitted light beam including a sensing signal and a reference signal, and a processor electrically coupled to the detector arrangement, the processor configured to perform a subtraction operation between the sensing signal and the reference signal. The optical sensing is based on a differential measurement scheme. The subtraction between the sensing signal and the reference signal cancels the common path noise and enhances the sensor resolution.
