The performance of the tapered velocity coupler for single mode fibers is investigated theoretically and experimentally. An improved analytical solution convenient for analyzing and designing the tapered velocity couplers is derived. The mode cross-talk in the tapered region and the mode conversion loss due to the discontinuity at the ends of the fibers are measured and are compared with the theoretical results. Simultaneous shaping of the multiple single mode fibers into tapered structure is successfully realized and a low loss splicing (less than 0.2 dB) is achieved either by using adhesives or by the thermal fusion technique.

A quantum interconnection scheme by controlling the Coulomb interaction between ballistic electrons is proposed in which 2DEG (2 dimensional electron gas) plays the role of an interconnection medium. This concept brings up new possibilities for the interconnection approach in various fields such as parallel processing, telecommunications switching, and quantum functional devices. Cross-over interconnection, address collision, and address selection in a quantum information network system were analyzed as the first step. The obtained results have shown that the interconnection probability can be controlled by the velocity and timing of the ballistic electron emission from the emitter electrode. The proposed interconnection scheme is expected to open up a new field of quantum effect integrated circuits in the 21st century.