title: Signed frequency offset measurement for direct detection DPSK system with a chromatic dispersion offset.
abstract: We demonstrated a method for the measurement of signed frequency offset between optical source and delay interferometer (DI) for 10 Gb/s DPSK signals based on asynchronous delay-tap sampling technique with a chromatic dispersion (CD) offset. The demodulated DPSK signals show asymmetrical property and amplitude shoulder appears on the waveforms with frequency offset and a fixed CD offset together. The delay-tap sampling scatter plots also show the asymmetry related to the asymmetrical signal distortion. Our proposed method cannot only realize the measurement of the magnitude of frequency offset but also the polarity. The measurement range is from -2 GHz to +2 GHz and the sensitivity can reach ±100MHz. The simulation and experimental results are demonstrated and in good agreement.
authors.affiliation: Tianjin University of Technology, Engineering Research Centre of Communication Devices (Ministry of Education), Tianjin Key Laboratory of Film Electronic and Communication Device, School of Computer and Communication Engineering, Tianjin 300000, China. hkzhaojian@gmail.com
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Alan Pak Tao
authors.initials: AP
authors.lastname: Lau
authors.forename: Khurram Karim
authors.initials: KK
authors.lastname: Qureshi
authors.forename: Chao
authors.initials: C
authors.lastname: Lu
authors.forename: X R
authors.initials: XR
authors.lastname: Ma
authors.forename: H Y
authors.initials: HY
authors.lastname: Tam
authors.forename: P K A
authors.initials: PK
authors.lastname: Wai