180 $^{\circ}$ Light Path Conversion Device With Tapered Self-Written Waveguide for Optical Interconnection

A 180° light path conversion device with a tapered self-written waveguide (SWW) is proposed for optical interconnection. Larger tolerance width and improved light-coupling efficiency are expected when coupling this device to optical devices, because the size of the end faces at both the light-emitting and light-receiving devices can be optimized, owing to the tapered shape of the SWW. A ray-tracing simulation indicates that positional tolerance width of 1 dB down can be increased more than two fold by fabricating a tapered core. We constructed a prototype device with a tapered SWW and achieved optical coupling efficiency of -3.6 dB.