Double acousto-optic deflector system for increased scanning range of laser beams

Temperature Effects in an Acousto-Optic Modulator of Terahertz Radiation Based on Liquefied SF6 Gas

The acousto-optic (AO) diffraction of terahertz (THz) radiation in liquefied sulfur hexafluoride (SF6) was investigated in various temperature regimes. It was found that with the increase in the temperature from +10 to +23 °C, the efficiency of the AO diffraction became one order higher at the same amplitude of the driving electrical signal. At the same time, the efficiency of the AO diffraction per 1 W of the sound power as well as the angular bandwidth of the efficient AO interaction were temperature independent within the measurement error. Increase of the resonant sound frequency with decreasing temperature and strong narrowing of the sound frequency bandwidth of the efficient AO interaction were detected.

Two-dimensional beam-steering device using a doubly periodic Si photonic-crystal waveguide

We demonstrate a nonmechanical, on-chip optical beam-steering device using a photonic-crystal waveguide with a doubly periodic structure that repeats the increase and decrease of the hole diameter. We fabricated the device using a complementary metal-oxide-semiconductor process. We obtained a beam-deflection angle of 24° in the longitudinal direction, while maintaining a divergence angle of 0.3°. Four such waveguides were integrated, and one was selected by a Mach-Zehnder optical switch. We obtained lateral beam steering by placing a cylindrical lens above these waveguides. By combining the lateral and longitudinal beam steering, we were able to scan the collimated beam in two dimensions, with 80 × 4 resolution points.