A 40-Gb/s duobinary carrier-suppressed return-to-zero (DCS-RZ) signal format generated from phase-modulated (PM) duobinary signals by using a phase modulator and an external intensity modulator is proposed. The transmission performance of the proposed DCS-RZ format is theoretically investigated. The proposed DCS-RZ format can produce a signal bandwidth similar to that produced by the conventional DCS-RZ format generated from conventional duobinary signals using lowpass filters. However, the receiver sensitivities of the proposed DCS-RZ format can be improved by about 2 dB more than those of the conventional DCS-RZ format due to high extinction ratio and nonlinear tolerance. Due to a short pulse of the proposed DCS-RZ format, the tolerance of the first-order polarization mode dispersion (PMD) for the format can be improved by about 1 dB up to the differential-group-delay (DGD) value of 16 ps.
Bibliographical noteFunding Information:
Manuscript received January 1, 2006; revised June 1, 2006. This work was supported in part by the Brain Korea 21 in 2006 and the National Research Laboratory (NRL) programs in South Korea.
- Modulation format
- Optical comniunication
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics