T. Kirihara et al., LOSSLESS AND LOW CROSSTALK 4X4 OPTICAL SWITCH ARRAY, Electronics & communications in Japan. Part 2, Electronics, 77(11), 1994, pp. 73-81
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.