Variable-Bandwidth Superchannels Using Synchronized Colorless Transceivers

We propose a modular architecture for long-haul optical networks supporting flexible-bandwidth superchannels. Colorless transceivers can be designed to modulate/detect up to M = 4 subcarriers, each at a symbol rate of 12.5 Gbaud, achieving a maximum bit rate of 200 Gbit/s, assuming polarization-multiplexed quadrature phase-shift keying (PM-QPSK). A set of N synchronized transceivers can cooperate to modulate/detect a superchannel comprising N·M subcarriers using no-guard-interval orthogonal frequency-division multiplexing, enabling transmission at bit rates beyond 1 Tbit/s. We analyze and simulate the performance of the proposed architecture in the presence of linear fiber impairments and synchronization errors and establish design requirements for practical deployment of the architecture. Simulation results are shown for transmission of a superchannel comprising 24 subcarriers, which conveys approximately 1.1 Tbit/s with a spectral efficiency of 3.5 bits/s/Hz using PM-QPSK.