Research/MEMS-NEMS Photonic Crystal Devices

2019-02-18 (月) 00:12:02 (542d)

Miniaturization of Planar Lightwave Circuit



Most planar lightwave circuits made of glass substrates are made large (from a MEMS point of view) because traveling light cannot make a quick turn in the waveguide but it leaks out of the core owing to the small difference of refractive indices between the waveguide core and the clad (substrate). Furthermore, the change of refractive index by, for instance, thermo-optical effect, is very small (less than 1 %), which makes the optical modulator large. The purpose of this project is to develop ultimately small optical circuits by using the silicon photonic band-gap crystal (PhC) waveguide with micromechanical optical modulator that works in the evanescent field over the waveguide.

Micromechanical Optical Modulation in Evanescent Field



It has been long known that the light traveling in the waveguide can be intensity-modulated by bringing a piece of dielectric/metal material into the close vicinity of the waveguide, which is called the "evanescent field," where a fraction of optical energy is smearing out from the waveguide core. We use the MEMS techinque to bring a micro piece of silicon into the evanescent field to induce optical modulation.

MEMS PhC Structure



We used electrostatic operation of a polysilicon cantilever / bridge structure that over-hangs across the PhC waveguide. The PhC waveguide is made by silicon DRIE on a thin SOI layer, and the micromechanical structure is made by the surface micromachining of an LPCVD polysilcon film.

Contact Investigators

  • Akio Higo and Prof. Satoshi Iwamoto (IIS / RCAST, University of Tokyo)


  1. A. Higo, S. Iwamoto, M. Ishida, Y. Arakawa, H. Fujita, A. Gomyo, M. Tokushima, H. Yamada, and H. Toshiyoshi, "Design and Fabrication of MEMS Optical Modulators Integrated with PhC Waveguides," IEEE/LEOS Int. Conf. on Optical MEMS and Their Applications, August 1-4, 2005, Oulu, Finland. (to be oral presented, G4)