Two-Dimensional Beam Steering Device Using Double Periodic Si Photonic Crystal Waveguide

We demonstrate a non-mechanical on-chip optical beam steering device using the photonic crystal waveguide with a double periodic structure that repeats the increase and decrease of hole diameter. Guided slow light in this waveguide is radiated to be a light beam. Slow light shows strong dispersion, which allows a deflection angle of approximately 10 times that of a normal diffraction grating. We fabricated the device using complementary metal oxide semiconductor process and observed a beam deflection angle of 24 degrees in the longitudinal direction with maintaining the divergence angle of 0.3 degrees when the wavelength was changed by 27 nm. Four such waveguides were integrated, and one of them was selected by a Mach-Zehnder optical switch. Then, the lateral beam steering was obtained when a cylindrical lens was placed above these waveguides. By combining the longitudinal and lateral beam steering, the collimated beam was scanned two-dimensionally with 80 x 4 resolution points.