Experimental Assessment of Filter Narrowing Effect for Low Bandwidth Connections in EON

In this letter, we experimentally analyze the filter narrowing effect for low bandwidth connections in the context of the flexi-grid paradigm for optical aggregation networks. First of all, we characterize the concatenation of up to 12 filters by means of a high resolution optical spectral analyzer. Then, we set up the programmable filters with the obtained characterization, in order to emulate the filter concatenation impairments. The studied filters have nominal bandwidths of 12.5 GHz, 25 GHz, and 50 GHz. The two potential candidates analyzed are intensity modulation/direct detection on-off keying and direct detection orthogonal frequency division multiplexing (OFDM) with uniform and bit loading. Results show a significant signal degradation for filter bandwidths of 12.5 GHz with respect to 25 GHz and 50 GHz, considering a net bit rate of 10 Gb/s. We also conclude that for future entire flexi-paradigm, OFDM is an appropriate candidate.