Ultra-fast all-optical integrated differentiators in Bragg gratings

In this work we present the design and first experimental demonstration of integrated-waveguide, ultra-fast all-optical differentiator based on π-phase-shifted Bragg gratings. Such a photonic device was achieved in deeply-side-etched Silicon-on-Insulator (SOI) ridged waveguides. High coupling coefficient, up to 1.15^∗ 10⁵ m⁻¹, achieved in fabricated set of devices, allows for the wide operational bandwidth, resulting in terahertz-processing speeds, experimentally obtained on sub-millimetres length scales. Moreover, using our device, we have managed to generate sub-picosecond Hermite-Gaussian pulse waveforms. The proposed optical element, allowing for complete operations to be performed on a single chip, is a subject for many potential applications in ultra-fast data processing and analysis, giving inter alia a possibility for analog solving of differential equations. It can be also used in optical ultra-fast coding, sensing, pulse shaping and communications.