Narrowband 2/spl times/10 Gbit/s quaternary intensity modulation based on duobinary modulation in two polarizations with unequal amplitudes

Abstract

Two duobinary 10 Gbit/s data streams with orthogonal polarizations and unequal amplitudes allow to generate a narrowband 20 Gbit/s quaternary intensity modulation. Sensitivity and CD tolerance of this generation scheme are -17.6dBm and 530ps/nm, respectively.

Quantum limit of optimum four-level ASK signals with direct detection optically preamplified receivers

“…With the rapid growth of Internet traffic congestion, efficiently using signal bandwidth is essential to increase the transmission capacity over already installed optical fibers and amplifiers. Multilevel amplitude-shifted-keying (ASK) format such as 4ASK has recently attracted much attention because it offers an increased spectral efficiency at a reduced symbol rate without too complex transmitting and receiving ends [1][2][3][4][5]. Benefited from the reduced symbol rate, the tolerances to chromatic dispersion (CD) and polarization mode dispersion (PMD) are enhanced compared to traditional binary format [1, 3,5].…”