Yan S, Cheng Z, Frandsen LH, Ding Y, Zhou F, Dong J, Zhang X. Bandwidth-adaptable silicon photonic differentiator employing a slow light effect.
Opt Lett 2017;
42:1596-1599. [PMID:
28409807 DOI:
10.1364/ol.42.001596]
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Abstract
A photonic differentiator (DIFF) plays a crucial role in photonic circuits. Despite the fact that a DIFF having a terahertz bandwidth has been reported, the practical bandwidth is limited to being a bandpass response. In this Letter, we propose the concept of a bandwidth-adaptable DIFF, which exploits the slow light effect in a photonic crystal waveguide (PhCW) to overcome the inherent bandwidth limitation of current photonic DIFFs. We fabricated a PhCW Mach-Zehnder interferometer (PhCW-MZI) on the silicon-on-isolator material platform to validate our concept. Input Gaussian pulses with full width to half-maximums (FWHMs) ranging from 2.7 to 81.4 ps are accurately differentiated using our PhCW-MZI. Our all-passive scheme circumvents the bandwidth bottlenecks of previously reported photonic DIFFs and can greatly broaden the application area of photonic DIFFs.
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