1. NTT Device Technology LaboratoriesNTT Corporation, 3–1 Morinosato‐WakamiyaAtsugi243‐0198KanagawaJapan
2. Optics and Electronics LaboratoryFujikura Ltd.1440, MutsuzakiSakura285‐8550ChibaJapan
3. Graduate School of Engineering, Osaka Prefecture University1‐1 Gakuen‐cho, Naka‐kuSakai599‐8531OsakaJapan