Optical guided-wave devices are of interest as sensors because the active device can be small and nonperturbing. An integrated optical modulator can form a compact electric field detector and has no long, electrically-conductive leads that can be perturbing. A channel waveguide device, with small dimensions and closely spaced electrodes, is much more sensitive than a bulk device and is therefore more useful where small physical parameters are to be detected. Lithium niobate (LiNbO3) is a suitable material in which to form a sensor; it has large electro-optic coefficients, which make it responsive to small fields, and low optical loss.
by Catherine H. Bulmer