Tunable optical delay line in SOI implemented with step chirped Bragg gratings and serial grating arrays

Mina Spasojevic; Lawrence R. Chen

doi:10.1117/12.2037832

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11 October 2013 Tunable optical delay line in SOI implemented with step chirped Bragg gratings and serial grating arrays

Mina Spasojevic, Lawrence R. Chen

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Proceedings Volume 8915, Photonics North 2013; 89150S (2013) https://doi.org/10.1117/12.2037832
Event: Photonics North 2013, 2013, Ottawa, Canada

Abstract

Tunable optical delay devices have numerous applications in optical communications [1] and have been successfully implemented using slow light elements and fiber or waveguide gratings. There has been considerable interest in siliconon- insulator (SOI) as a technology platform for compact integration of optical signal processing systems. SOI-based delay lines have been realized using coupled ring resonators [2], photonic crystals [3], and various Bragg grating-based configurations including single or coupled chirped sidewall gratings [4,5] as well as tapered rib waveguide gratings [6]. By linearly chirping the period in sidewall gratings, relatively small delays (a few ps) over a bandwidth of tens of nm were demonstrated [4]; with tapered waveguides, significantly larger delays (300-500 ps) were obtained, albeit over a narrower bandwidth (< 2 nm) [6]. On the other hand, some signal processing applications may require large delays (e.g., tens to hundreds of ps) over large bandwidths (several to tens of nm). Several designs have been proposed to meet these requirements, e.g., a step-chirped rib waveguide grating providing 50 ps delay over 15 nm [7] or complementary apodized sidewall gratings providing up to 275 ps over 3 nm [8], however, they have not been realized experimentally. In this paper, we demonstrate discretely tunable optical delay lines that provide tens of ps delay (up to 65 ps) in steps of 15-32 ps over bandwidths of several tens of nm (35-70 nm). The devices are fabricated on SOI using electron beam lithography and implemented through two different approaches: serial sidewall Bragg grating arrays and the step-chirped sidewall Bragg gratings.

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Mina Spasojevic and Lawrence R. Chen "Tunable optical delay line in SOI implemented with step chirped Bragg gratings and serial grating arrays", Proc. SPIE 8915, Photonics North 2013, 89150S (11 October 2013); https://doi.org/10.1117/12.2037832

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