Observation of micromechanically controlled tuning of photonic crystal line-defect waveguide

We fabricated a photonic crystal (PC) line-defect waveguide integrated with a microelectromechanical actuator and demonstrated the optical switching operation. The device consisted of a PC line-defect waveguide fabricated in a silicon-on-insulator substrate and a polycrystalline-Si dielectric plate located above the PC waveguide. An applied voltage moved the dielectric plate towards the PC surface due to the electrostatic force. This motion increased out-of-plane scattering of the guided light through the evanescent interaction with the dielectric plate, and modulated the transmittance of the PC waveguide. With only a 5 μm interaction length, an extinction ratio of ∼10 dB was obtained at a wavelength of 1568 nm under an applied voltage of 60 V. The response time of the switching operation was approximately 1 ms.