Optical characteristics of transverse A-O waveguide devices with SAW by FDTD analysis

Acousto-Optic(A-O) waveguide devices have been used in the photonics network such as switch, tunable filter and wave separator in wavelength division multiplexed system, etc. Most of the works employ collinear devices, where acoustic waves and optical signals propagate along the longitudinal propagation direction in an integrated optical waveguide device. Transverse A-O waveguide device using surface acoustic wave (SAW) is expected to overcome the slow responses of collinear devices and accomplish Gigabit class high speed switching. When SAW is propagating in a direction transverse to the optical signal propagation direction in a slab optical waveguide, due to the A-O effect, the refractive index (permittivity) of waveguide will be modulated. Accordingly, optical signal is derived with mode conversion and change in propagation constant. These effects can be used to construct optical devices for high speed modulation and switching applications. In this paper, we have presented the optical propagation characteristics of optical fundamental mode launched in to A-O waveguide, investigated using numerical computer simulation of Finite Difference Time Domain (FDTD) analysis. We have investigated the optical mode conversion and phase modulation using FDTD computer simulations.