New approaches to practical guided-wave passive devices based on ion-exchange technologies in glass

For the use in cost-effective optical communication systems, two types of guided-wave devices have been studied using ion exchange in glass: (1) A microlens-loaded coupler module composed of a polarization-maintaining fiber array, a directional coupler and a twin-microlens array for coherent balanced receivers has been proposed and fabricated with an excess loss of 1.0 dB and an extinction ratio of _> 20 dB for 0-60 degC operation. (2) An optimum mask pattern for splitters has been devised theoretically and verified experimentally, which has reduced the scattering loss to < .0.1 dB and also suppressed their possible bimodal behavior in the branching region.