Azaña, J.3; Oxenløwe, Leif Katsuo1; Palushani, Evarist2; Slavík, R.5; Galili, Michael1; Mulvad, Hans Christian Hansen1; Hu, Hao1; Park, Y.3; Clausen, Anders1; Jeppesen, Palle1
1 Department of Photonics Engineering, Technical University of Denmark2 High-Speed Optical Communication, Department of Photonics Engineering, Technical University of Denmark3 Centre National de la Recherche Scientifique4 University of Southampton5 University of Southampton
We review recent work on all-fiber (long-period fiber grating) devices for optical pulse shaping, particularly flat-top pulse generation, down to the subpicosecond range and their application for nonlinear switching (demultiplexing) of optical time-division multiplexed (OTDM) data signals in fiber-optic telecommunication links operating up to 640 Gbit/s. Experiments are presented demonstrating error-free 640-to-10 Gbit/s demultiplexing of the 64 tributary channels using the generated flat-top pulses for temporal gating in a Kerr-effect-based nonlinear optical loop mirror. The use of flat-top pulses has critical benefits in the demultiplexing process, including a significantly increased timing-jitter tolerance (up to ~500 fs, i.e., 30% of the bit period) and the associated improvement in the bit-error-rate performance (e.g., with a sensitivity increase of up to ~13 dB as compared with the use of Gaussian-like gating pulses). Long-period fiber grating pulse shapers with reduced polarization dependence are fabricated and successfully used for polarization-independent 640-to-10 Gbit/s demultiplexing experiments.