Investigation on the sensitivity of direct coupling porous silicon membrane waveguide sensor

A direct coupling porous silicon waveguide biosensor structure utilizing propagation wave is proposed. The waveguide sensor has a porous silicon membrane as the core and two metal layers as cladding. Direct coupling of light is possible due to attenuated total reflection at the air-metal interface. Sensitivities of two interrogation methods using this sensor structure have been studied, the mode angle shifting (MAS) method and the reflectance shifting (RS) method. Relationships between sensitivity and mode angle, porous silicon membrane thickness, and laser source wavelength and polarization have been investigated through simulation.