Design of a compact atto-joule-per-bit bus-coupled photonic nanocavity switch

Abstract

We experimentally demonstrate an array of bus-coupled compact one-dimensional photonic crystal nanocavities with large extinction, high-quality factor, and large free spectral range (FSR) exceeding 300 nm centered on the telecom wavelength at 1550 nm. We present designs for an oxide-clad bus-coupled PC switch with 0.96 dB insertion loss, 4.33 dB extinction, and ∼260 aJ/bit switching energy by careful control of the cavity geometry as well as p-n junction doping. We also demonstrate that air-clad bus-coupled PC switches can operate with 1 dB insertion loss, 3 dB extinction, and ∼80 aJ/bit switching energy. We present a design route integrating phase change materials that can undergo a controlled transition between amorphous to crystalline material phases of the PCMs for a large change in refractive index. The large index change can overcome fabrication imperfections to effectively align the PC nanocavity resonance to the source laser wavelength thereby enabling true atto-joule per bit operation without the need for active power-consuming thermal heaters.