The impact of optical OFDM (orthogonal frequency division multiplexing) with adaptive modulation on reducing the filter concatenation effect is investigated, for the first time, in intensity modulation and direct-detection transparent metropolitan/regional network systems incorporating cascaded reconfigurable optical add/drop multiplexers (ROADMs). The ROADMs considered are based on different optical filters including fiber Bragg grating, Chebyshev, thin film and wavelength-blocker/wavelength-selective switch devices. It is shown that, in comparison with conventional identical modulation, adaptive modulation can improve the system performance by a factor of up to 60%. The utilization of adaptive modulation can also significantly enhance the network tolerance to filter loss ripple, group delay ripple and frequency dip.
© 2011 OSA
Original Manuscript: March 29, 2011
Revised Manuscript: June 2, 2011
Manuscript Accepted: June 2, 2011
Published: June 28, 2011
Elias Giacoumidis, Ioannis Tomkos, and J. M. Tang, "Adaptive Modulation-Induced Reduction in Filter Concatenation Impairment for Optical OFDM Metro/Regional Systems," J. Opt. Commun. Netw. 3, 587-593 (2011)