title: Optical 60° hybrid for demodulating six-level DPSK signal.
abstract: We propose and demonstrate an optical 60° hybrid for demodulating optical signals with six-level DPSK modulation format. The proposed device consisting of a paired-interference 2∶6MMI coupler, phase shifters, and 2∶2MMI couplers with an asymmetric splitting ratio of 72∶28 exhibited hexagonal phase response over a C-band range.
authors.affiliation: Fujitsu Laboratories Ltd., Atsugi, Japan. jeong.sh@jp.fujitsu.com
authors.forename: Seok-Hwan
authors.initials: SH
authors.lastname: Jeong
authors.forename: Ken
authors.initials: K
authors.lastname: Morito