Optical Differential Phase-Shift Keying

Optical differential phase-shift keying (ODPSK) has emerged as a promising modulation format for state-of-the-art optical transport networks owing to its capability to enable optical transmissions with high receiver sensitivity, high spectral efficiency, and high tolerance to chromatic dispersion (CD), polarization-mode dispersion (PMD), and optical filtering. In this Chapter, the fundamentals, principles, implementations, and system impacts of ODPSK are reviewed. ODPSK is further categorized, based on its symbol constellation, into optical differential binary phase-shift keying (ODBPSK) and optical differential multilevel phase-shift keying (ODMPSK) that includes optical differential quadrature phase-shift keying (ODQPSK). For each ODPSK category, its transmitter and receiver implementations, fundamental receiver sensitivity, and tolerance to linear and nonlinear transmission impairments are described. Forward-looking topics on soft-detection of ODPSK, wavelength conversion and optical regeneration of ODPSK, optical packet switching based on ODPSK, are briefly discussed.