JPS6473301A - Single-mode star coupler - Google Patents

Abstract

PURPOSE:To narrow down the gap of an optical waveguide for connecting an input and an output optical fiber and to reduce its loss by structuring the optical waveguide for a directional coupler which is formed on a substrate and distributes light beams equally so that the optical waveguides crosses each other through the directional coupler which provides 100% coupling. CONSTITUTION:The directional coupler 20 which has an almost 100% coupling rate is formed at the position of a conventional optical waveguide instead of the optical waveguide. For example, one of optical signals distributed equally by, for example, a directional coupler 15 is incident on the directional coupler 16 and distributed equally. The other light signal is incident on the directional coupler 20, but the directional coupler 20 distributes almost 100% of the light power to another optical waveguide, so the other optical signal is guided to a directional coupler 16' and distributed equally. The optical signal which is incident from an optical fiber 17a for input is therefore guided out of respective optical fibers 18a-18d for output while almost equal to one another. Consequently, the gap of optical waveguides to be connected to the input and output optical fibers is narrowed down and the loss is reduced.