title: Terahertz bandwidth all-optical Hilbert transformers based on long-period gratings.
abstract: A novel, all-optical design for implementing terahertz (THz) bandwidth real-time Hilbert transformers is proposed and numerically demonstrated. An all-optical Hilbert transformer can be implemented using a uniform-period long-period grating (LPG) with a properly designed amplitude-only grating apodization profile, incorporating a single π-phase shift in the middle of the grating length. The designed LPG-based Hilbert transformers can be practically implemented using either fiber-optic or integrated-waveguide technologies. As a generalization, photonic fractional Hilbert transformers are also designed based on the same optical platform. In this general case, the resulting LPGs have multiple π-phase shifts along the grating length. Our numerical simulations confirm that all-optical Hilbert transformers capable of processing arbitrary optical signals with bandwidths well in the THz range can be implemented using feasible fiber/waveguide LPG designs.
authors: Institut National de la Recherche Scientifique—Énergie, Matériaux et Télécommunications, 800 de la Gauchetière Ouest, Suite 6900, Montréal, Québec H5A 1K6, Canada. ashrafi@emt.inrs.ca
authors: Reza
authors: R
authors: Ashrafi
authors: José
authors: J
authors: Azaña