PLANAR OPTICAL WAVEGUIDES WITH DOUBLE GROOVES

摘要

A planar optical waveguiding device (e.g. a device implemented in silica glass) includes at least one section of core (10) which is located between a nd adjacent to two grooves (11, 12). The refractive index within the grooves (1 1, 12) is substantially equal to one and the grooves (11, 12) are located so th at the evanescent fields of optical signals travelling in the core (10) extend into the grooves (11, 12). Preferably the grooves (11, 12) have a direct interface with the core (10) and they extend through a layer (21) located above the core (10) into a layer (22) located below the core (10). Where the cores (10) have bends, e.g. bends with radii of curvature below 2 mm (and especially below 500 .mu.m) the grooves (11, 12) are located both inside and outside the bends.