Dispersion tailoring and soliton propagation in silicon waveguides

Institute of Optics, University of Rochester, Rochester, New York, United States
Optics Letters (Impact Factor: 3.29). 06/2006; 31(9):1295-7. DOI: 10.1364/OL.31.001295
Source: PubMed


The dispersive properties of silicon-on-insulator (SOI) waveguides are studied by using the effective-index method. Extensive calculations indicate that an SOI waveguide can be designed to have its zero-dispersion wavelength near 1.5 microm with reasonable device dimensions. Numerical simulations show that soliton-like pulse propagation is achievable in such a waveguide in the spectral region at approximately 1.55 microm. The concept of path-averaged solitons is used to minimize the impact of linear loss and two-photon absorption.

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    • "μm close to the bandgap wavelength. Moreover , even if the waveguide size is increased to move the ZDW to longer wavelength, the dispersion slope near the ZDW is not small, as shown in [187] [188] [189], causing a limited low-dispersion bandwidth. Recently, a dispersion engineering technique for integrated high-index-contrast waveguides has been proposed , in which an off-center nano-scale slot controls modal distribution at different wavelengths [59] [60]. "
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    ABSTRACT: Group IV photonics hold great potential for nonlinear applications in the near- and mid-infrared (IR) wavelength ranges, exhibiting strong nonlinearities in bulk materials, high index contrast, CMOS compatibility, and cost-effectiveness. In this paper, we review our recent numerical work on various types of silicon and germanium waveguides for octave-spanning ultrafast nonlinear applications. We discuss the material properties of silicon, silicon nitride, silicon nano-crystals, silica, germanium, and chalcogenide glasses including arsenic sulfide and arsenic selenide to use them for waveguide core, cladding and slot layer. The waveguides are analyzed and improved for four spectrum ranges from visible, near-IR to mid-IR, with material dispersion given by Sellmeier equations and wavelength-dependent nonlinear Kerr index taken into account. Broadband dispersion engineering is emphasized as a critical approach to achieving on-chip octavespanning nonlinear functions. These include octave-wide supercontinuum generation, ultrashort pulse compression to sub-cycle level, and mode-locked Kerr frequency comb generation based on few-cycle cavity solitons, which are potentially useful for next-generation optical communications, signal processing, imaging and sensing applications.
    Nanophotonics 08/2014; 3(4-5). DOI:10.1515/nanoph-2013-0020 · 5.69 Impact Factor
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    • "It is difficult to achieve because of strong wavelength-dependent dispersion in high-index-contrast silicon waveguides [15], [16]. Modifying the dimensions of a silicon waveguide can shift the zero-dispersion wavelength (ZDW) widely [17]–[19], but the dispersion flatness is not sufficiently improved to support ultrabroad continuum generation. The introduction of a nanoscale slot opens a new opportunity in dispersion engineering [20]–[22]. "
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    IEEE Journal of Selected Topics in Quantum Electronics 11/2012; 18(6):1799-1806. DOI:10.1109/JSTQE.2012.2200032 · 2.83 Impact Factor
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    • "Interestingly, these nonresonant effects are further enhanced inside SOI waveguides because of a tight mode confinement leading to a relatively small effective mode area ( 1 m ). Further, the dispersion inside SOI waveguides can be easily tailored by adjusting the waveguide geometry [7]–[10]. All these amalgamate to a material with rich optical features and great potential for structural and performance engineering, making silicon a viable alternative and a potential contender for integrated optics applications [11]–[13]. "
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    ABSTRACT: Owing to recent progress in silicon-on-insulator (SOI) technology for signal processing of optical pulses, a detailed intuitive understanding of the different processes governing pulse propagation through SOI waveguides is desired. Even though it is possible to carry out numerical simulations to characterize device performance by varying material and pulse parameters, such an approach does not provide an intuitive understanding. For this reason, we develop an analytic approach in this paper and present approximate solutions that are valid under realistic conditions and characterize with reasonable accuracy the dynamical evolution of a short optical pulse through SOI waveguides. Our analytical expressions take into account linear losses, Kerr nonlinearity, two-photon absorption, and free-carrier effects (both absorptive and dispersive) and thus are likely to be useful for a variety of applications in the area of silicon photonics. Even though free-carrier absorption is included, we limit our analysis to the case where its influence on the temporal pulse shape is minimal. To provide a comprehensive understanding of our results and to validate their accuracy, we consider general properties of our analytical solutions, analyze their applicability in different parametric ranges relevant for applications, and compare them with published results. We envision utilizing these results in optimizing the design of SOI-based devices aimed at integrated optics applications.
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