Discretely tunable optical delay lines using serial and step-chirped sidewall Bragg gratings in SOI

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Why is it important?

In this paper, we report the realization of discretely tunable optical delay lines using sidewall Bragg gratings in SOI. We achieved tens of ps of delay (up to 60 ps) in steps of 20 ps spanning a bandwidth of several tens of nm (up to 53 nm) using devices based on serial grating arrays or step-chirped gratings. In contrast, previously reported experimental demonstrations involve smaller delays (several ps) spanning broad bandwidths (tens of nm) or larger delays (up to several hundred ps) spanning a narrow bandwidth. Our delay lines should allow for certain signal processing functions (those requiring tens of ps delay spanning bandwidths of tens of nm) to be implemented on-chip.