Bragg grating based integrated photonic Hilbert transformers

Photonic Hilbert transformers based on planar Bragg grating are proposed and experimentally demonstrated. Planar Bragg gratings with apodization profiles and phase shifts are utilized to implement a general Hilbert transform, fractional order Hilbert transforms and terahertz bandwidth Hilbert transforms, and devices are fabricated by using a phase-modulated direct UV grating writing technique in a silica-on-silicon platform. The design, fabrication, integration and characterization of the proposed grating structures are discussed and presented.