Gain-Assisted Surface Plasmon Resonance Refractive Index Sensor

Surface plasmon resonance (SPR) has been a topic of intense research in refractive index sensors due to the benefits of high resolution, high sensitive, real-time, and label-free technology. But losses restrict the operational parameters of SPR-based devices. In this paper, a new design of SPR sensor structures using gain medium are proposed. These novel prisms-based structures are based on Otto and Kretschmann configurations. Regard to gain coefficient of an active layer, two different regimes have been introduced in which loss compensating and amplifying surface plasmons polaritons are occurred. The effect of geometrical parameters on SNR enhancement factor is investigated theoretically and finally, the optimum layers' thicknesses for the fixed values of gain coefficient and wavelength will be examined. Signal-to-noise ratio in the proposed structures could be enhanced by a factor of two orders of magnitudes.