Silicon Optical Nanocavities for Multiple Sensing

This paper investigates an optical nanocavity sensor based on a 1D photonic bandgap. The sensor is unique in that it provides high -factor (sensitivity), and low attenuation and wavelength variation. It incorporates an optical splitter/combiner structure in realizing multiple sensing. Active sensing can be achieved by implementing a p-i-n diode. The optical diode requires an on state power of 81 nW with rise and fall times of 0.2 ns and 0.043 ns, respectively. The sensitivity of the active sensor, at 120, is a magnitude higher than conventional surface sensing and is characterized with respect to the optical phase change and by the diode biasing voltage. It will be shown that the aspect of multiple sensing, resonant wavelengths, the Q-factor and transmission can be optimized by tuning the length of the cavity and the radius of the two innermost air holes. This method allows ease of fabrication by not having to vary the waveguide width and height to obtain tuning effects.