title: A comparison of modulation formats for passive optical networks.
abstract: The sensitivity of the four-dimensional modulation format, polarization-switched quadrature phase shift keying (PS-QPSK), is compared with polarization division multiplexed QPSK (PDM-QPSK), binary phase shift keying (PDM-BPSK) and 8-ary quadrature amplitude modulation (PDM-8QAM) at a constant bitrate (12.5 Gbit/s) using a preamplified signal to improve receiver sensitivity. The sensitivity without preamplification is also obtained. PS-QPSK is found to maintain a sensitivity advantage over the reference formats in line with theory with an absolute sensitivity of -52.7 dBm (4.2 photons/bit), assuming hard decision FEC.
authors.affiliation: Optical Networks Group, UCL Electronic & Electrical Engineering, Torrington Place, London, WC1E 7JE, United Kingdom. d.lavery@ee.ucl.ac.uk
authors.forename: Domaniç
authors.initials: D
authors.lastname: Lavery
authors.forename: Carsten
authors.initials: C
authors.lastname: Behrens
authors.forename: Seb J
authors.initials: SJ
authors.lastname: Savory