A guided-wave surface plasmon resonance based sensor using graphene layer for detect the biomolecules has been analyzed. The use of waveguide layer between the gold film and graphene significantly improves the penetration depth and increases the sensitivity, then graphene layer is used to enhance the adsorption of the biomolecules. The thickness and materials of waveguide layer along with the number of graphene layer have been optimized to achieve the best performance of the sensor in terms of sensitivity. The highest sensitivity with 228.8°/RIU is obtained for visible wavelength with optimized thickness of gold and waveguide layer as 45nm and 10nm respectively while the materials of waveguide layer is chosen as zinc oxide and the optimum number of graphene layers is 2.We believe that this sensor could find potential applications in biological detection.
In order to explore the key factors of the SPR effect, such as sensitive material, thickness of sensitive metal film, incident angle and wavelength, especially the affection of the incident light wavelength on the modulated reflectivity, calculations and analyses are carried out in this paper. Simulation results show that Ag has the lowest reflectivity when the incident light with shorter wavelength in visible wave band, Au has the lowest reflectivity with red light, and Cu has the best effect from 600 nm to infrared band. The ranges of thickness measurement for thin films can be obtained when the light source wavelength and incidence angle are fixed with the adopted metal sensitive material. Moreover, there is a special range of incidence angle that can put up a significant SPR effect phenomenon when there are definite metal films and wavelength of incident light.
In this paper, the impacts of surface plasmon resonance (SPR) on the angular spin splitting of light are investigated theoretically. The expression for the angular spin splitting shifts is derived, and the angular shifts as the function of the angle of incidence under different metal film thicknesses are calculated. The simulation results manifest that the angular spin splitting is significantly enhanced when surface plasmons are strongly excited. Under the optimal parameter conditions, the largest angular shift is up to 4.493×10-5 rad. It is also found that the directions of spatial propagation of photons in the out-of-plane can be switched by adjusting the angle of incidence under certain conditions. These findings may provide a new way for photon manipulation and open another possibility for the development of new nano-photonic devices.
In this letter, we theoretically investigate the impact of the incident light polarization on photonic spin splitting induced by the photonic spin Hall effect when a linearly polarized Gaussian beam is reflected from an air-glass interface around the Brewster angle. We calculate the spin splitting shift as a function of the incident light polarization under different incident angles. We find that a tiny variation of the incident light polarization can result in a dramatic change of the spin splitting shift, and the highest sensitivity is up to 6.8 μm/deg . The largest splitting shift can reach 5.3 μm, which is larger than the previously reported values. We also find that the direction of spin accumulation of photons with different spin directions can be switched by adjusting the incident angle around the Brewster angle when the incident light polarization is near the p-polarization. These findings may be useful for precise polarization metrology and photon modulation.
In the three-dimensional angle measurement, yaw and pitch angle can be detected easily by several convention optical devices. While the roll angle is difficult to measure since its rotation axis is parallel to the incident plane. This work is based on the application of the Talbot effect with a Ronchi grating. The period of Moiré fringes which generated by two gratings will be changed with small rotation. The roll angle can be calculated by the width change of fringes.