LOSSLESS AND LOW CROSSTALK 4X4 OPTICAL SWITCH ARRAY

The optical switch array is a key device for realizing photonic switch ing systems. A lossless and low crosstalk switch is the most desirable component of large-scale switching systems which have more than 100 i nput/output ports. To realize such a switch monolithically, a carrier- injection-type optical single-slip structure (S-3) switch With traveli ng-wave amplifier (COSTA) have been proposed. To realize the COSTA, a carrier-injection-type optical switch and an optical amplifier that ar e suitable for integration have been developed. First, a carrier-injec tion-type optical switch where the PN junction was formed by crystal g rowth was fabricated. It was confirmed that the characteristics of the device do not deteriorate during heating, which makes it suitable for integration. Next, the structure of an optical amplifier which can be integrated into the optical waveguide using the reactive ion etching (RIE) process was investigated. An optical amplifier that was integrat ed into a straight optical waveguide was fabricated, and it was confir med that this amplifier could produce enough gain (internal gain of 25 dB) to compensate for the loss in the optical switch. Using these two basic techniques, a 4 x 4 COSTA was fabricated. With this 4 X 4 COSTA , fiber-to-fiber lossless (maximum gain of 5 dB) and extremely low cro sstalk characteristics (ON-OFF ratio of 54 dB) were demonstrated.