Extremely narrow resonances, giant sensitivity and field enhancement in low-loss waveguide sensors

Abstract

Low-loss waveguides (WGs), which support excitation of waveguide modes (WMs), are based on a dielectric WG separated from an absorptive film by a low-index dielectric spacer layer. We perform numerical and analytical study of the impact of the losses imposed to the WG in a planar sensing structure in the Kretschmann configuration on the resonance properties of the excitation. We demonstrate that the loss degree of the WMs can be controlled by the thickness of the spacer layer for both s and p polarizations. Extremely narrow resonances are discovered in the reflectivity spectra due to excitation of the low-loss WMs, and the maximum of the estimated sensitivity by intensity is found to be of 105-fold higher as compared to the conventional surface plasmon and WG-coupled surface plasmon sensors. We reveal the giant field intensity enhancement of 107-fold on the surface of the sensing structure in aqueous sensing media that can provide stronger fluorescence intensity at lower sample volumes for fluorescent labeling sensing.

Detection of Extremely Low Concentrations of Biological Substances Using Near-Field Illumination

“…It has been reported that a layered waveguide structure can generate a stronger and thicker enhanced electric field101112. Therefore, a sensor chip with a 36-nm thick Si layer and 364-nm thick SiO 2 layer placed on a 0.725-mm thick SiO 2 substrate was employed in the present system.…”

High performance optical systems using MIM based plasmonic structures

“…This Another metric that affects the sensor performance is the sensitivity by intensity. This metric relates the change in the power level to the change of the refractive index and is given by equation (7) as defined in [39][40][41]. For the proposed sensor, the maximum value for sensitivity by intensity is around 300 RIU −1 which is two orders of magnitude smaller when compared to 3.2 × 10 4 RIU −1 reported in [39] and 1.4 × 10 7 RIU −1 reported in [41].…”

“…This metric relates the change in the power level to the change of the refractive index and is given by equation (7) as defined in [39][40][41]. For the proposed sensor, the maximum value for sensitivity by intensity is around 300 RIU −1 which is two orders of magnitude smaller when compared to 3.2 × 10 4 RIU −1 reported in [39] and 1.4 × 10 7 RIU −1 reported in [41]. On the other hand, for the proposed sensor in this paper, an angular sensitivity of 120°RIU −1 is maintained compared to 30°RIU −1 reported in [39] and 16°RIU −1 reported in [41], which is four times greater than that reported in [39,41].…”

“…Nano-particle based sensor with sensitivity 650 nm RIU −1 around ∼1500 nm was proposed [38]. Despite their small size, plasmonic structures-based on the architectural design-might achieve high sensitivity by intensity and low limit of detection as proposed by [39][40][41] where detection limit down to 10 −5 is achieved while a sensitivity by intensity in the range of 10 7 RIU −1 .…”

Сравнительный Анализ Чувствительности Оптических Датчиков На Поверхностных Волнах, Возбуждаемых По Схеме Кречмана

“…Известно, что поверхностные волны могут распространяться и в диэлектрических [17], и комбинированных металлодиэлектрических [18] пленках планарных волноводов. В связи с этим было предложено [12,19] по схеме Кречмана возбуждать поверхностную волну в многослойной чисто диэлектрической структуре, представляющий из себя планарный волновод.…”