An ultra-high-speed photonic temporal differentiator using cascaded SOI microring resonators

A high-speed photonic temporal differentiator based on cascaded SOI microring resonators is proposed and experimentally demonstrated in this study. The first-order all-optical differentiation functionality is realized through approaching the critical coupling condition of the cascaded microring resonators. A three-stage double channel side-coupled cascaded microring structure is used to provide wider bandwidth and larger notch depth in its transmission spectrum. The fabricated cascaded SOI microring device is experimentally verified by Gaussian-like pulse trains with a data rate of up to 80 Gbit s−1. Due to the use of cascaded microring resonators, the notch depth in the transmission spectrum is increased from less than 30 dB to larger than 30 dB, thus the quality of the differentiated signal is improved.