Affiliation: | a Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577, Japan b Korea Photonics Technology Institute, 459-3 Bonchon-dong, Buk-gu, Gwangiu 500-210, South Korea c Department of Materials Engineering, Chungnam National University, Daeduk Science Town, Daejeon 305-764, South Korea d Lucent Technologies, Bell Laboratories, Murray Hill, NJ 07974-0636, USA |