Abstract
Insufficient receiver bandwidth destroys the orthogonality of Nyquist-shaped pulses, generating inter-symbol interference (ISI). We propose using an optical pre-sampler to alleviate the requirement on the receiver bandwidth through pulse re-shaping. Experiments and simulations using an optically shaped 40-Gbaud Nyquist-shaped on-off-keying signal (N-OOK) show receiver sensitivity improvements of 4- and 7.1-dB under 18- and 11-GHz receiver electrical bandwidths, respectively.
Highlights
Orthogonal multiplexing allows optical communication systems to efficiently occupy their available fiber bandwidth [1,2,3]
This is an extension paper of the work we presented at the Optical Fiber Communication Conference (OFC) [16], in which we discussed optical sampling of an electrically-shaped Nyquist on-off-keying (N-OOK) signal
We have experimentally demonstrated that the quality of a direct-detected, optically shaped 40-Gbaud Nyquist OOK signal can be improved by optical pre-sampling in a band-limited system, where the receiver bandwidths are below the single-sided bandwidth of the optical signal
Summary
Orthogonal multiplexing allows optical communication systems to efficiently occupy their available fiber bandwidth [1,2,3]. Orthogonal pulse shaping has received significant attention in systems employing coherent detection Direct-detection systems have recently been of interest for short-reach optical communication systems, and orthogonal multiplexing can be used in such systems These signals are received using direct detection without any ISI, if sampled at the ISI-free point, due to their time-domain orthogonality [3]. This orthogonality can be significantly degraded by electrical bandwidth limitations in the receiver
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