A grating-coupled surface plasmon resonance sensor based on bilayer aluminum nanowire arrays is fabricated by laser interference lithography. The device presents impressive reflective sharp peaks by lateral surface plasmon resonances even for aluminum thicknesses of merely several nanometers. Distinct reflective peaks and dramatic color shifts under different analytes are observed within a wide range of incident angle, metal thickness, and refractive index. The sensitivity of 307 nm per refractive index unit is experimentally obtained. The reflective-peak-type surface plasmon resonance sensors are suitable for practical applications because of easy fabrication, low cost, wide range, and high signal visibility.

Separating lights into different paths according to the polarization states while keeping their respective path’s polarizations with high purification is keen for polarization multiplex in optical communications. Metallic nanowire gratings with multi-slits in a period are proposed to achieve polarized beam splitters (PBSs) in reflection and diffraction. The setting of multi-slits largely reduces the reflection of photons with a transverse magnetific field via the plasmonic waveguiding effect, which leads to highly polarized output lights with extinction ratio larger than 20 dB in each channel. The proposed reflection/diffraction PBSs enrich the approaches to control the polarization states with the advantages of wide incident angles and flexible beam splitting angles.

A slim optical fingerprint recognition sensor (OFRS) based on a grating input coupler and a microprism sensing surface is proposed. By using a subwavelength grating coupler, input light is coupled into the planar waveguide and the propagation angle is well engineered to avoid image overlap, thus an undistorted fingerprint is captured. For maintaining a thin structure, a microprism array is utilized to facilitate the breaking of total internal reflection under a large diffraction angle from the grating. The feasibility, efficiency, and image quality of the proposed structure are verified and discussed. The device has the advantages of a slim structure, a high image contrast, and a compact architecture, suitable for mobile devices.