Photonic crystal biosensors based on surface plasmons

Surface plasmon photonic crystals can couple the incident light with surface plasmons by the periodic array of holes on the metal film. In this paper, surface plasmon photonic crystals with periodic square array of hexagon holes were fabricated. The infrared optical properties in transmittance and reflectance of the devices were tested. A sharp peak of surface plasmon resonance was observed at the incident angles of 30° and 90°. The optical wavenumber shift at 30° incident angle was used to detect the reaction of antigen and antibody, and the line correlation between protein concentrations and wavenumber shifts were investigated. By the comparison of the results between 4 ¿m and 8 ¿m periodic arrays, the 4 ¿m periodic structure has better performance. Based on the results, the surface plasmon photonic crystals can be used as biosensors.