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Journal ArticleDOI

Transverse localization of light in 1D disordered waveguide lattices in the presence of a photonic bandgap

TL;DR: In this article, the role of a prominent photonic bandgap (PBG) in the phenomenon of transverse localization of light in a semi-infinite lossless waveguide lattice consisting of evanescently coupled disordered one-dimensional optical waveguides has been investigated numerically.
Abstract: The role of a prominent photonic bandgap (PBG) in the phenomenon of transverse localization of light in a semi-infinite lossless waveguide lattice consisting of evanescently coupled disordered one-dimensional optical waveguides has been investigated numerically. The interplay between the underlying photonic bandgap due to inherent periodicity of the optical system and various levels of deliberately induced transverse disorder in its refractive index periodicity has been studied. We show that the PBG indeed plays an important role and that its simultaneous presence could catalyze realization of localized light even when the strength of disorder is not sufficiently strong to independently cause localization of light. An important outcome of this study revealed that the PBG could be gainfully exploited to tailor the spectral window for localization of light in potential applications such as lasing in a disordered optical lattice.
Citations
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Journal ArticleDOI
TL;DR: In this article, the influence of InP coupling cavity on Fano resonance of sub-wavelength MIM waveguide was studied by FDTD, and it was observed that the resonant wavelengths of mode mj (j = 1, 2, 3) were closely related with the height H 2 of the coupling cavity.
Abstract: In this paper, influence of InP coupling cavity on Fano resonance of sub wavelength MIM waveguide was studied by FDTD. It was observed that the resonant wavelengths of mode mj (j = 1, 2, 3) were closely related with the height H2 of InP coupling cavity. In addition, before and after the addition of air cavity, the relative farfield intensities I was a function of height H2. Therefore, InP as discrete state could be used as the filling dielectrics of Fano resonance in the MIM waveguide.

3 citations

Journal ArticleDOI
TL;DR: In this article, the FDTD of different waveguide structures with various vertical indirect coupled cavities were investigated by FDTD (finite difference-time domain) and the resonance peak at about 850nm moved to the long wavelength (redshift).
Abstract: In the paper, resonances of different waveguide structures with various vertical indirect coupled cavities were investigated by FDTD (finite difference-time domain). In the silicon cavity, Fano resonance could be observed at about 1430 nm. The coupling distance for the gold cavity/air cavity had less effect on the transmittance of the main waveguide but had a great influence on the transmission for water cavity in the visible region, which showed that water cavity could adjust resonance of waveguide structures. In addition, with the increment of refractive index n, the resonance peak at about 850 nm moved to the long wavelength (redshift). Dispersion rate about 2 × 10–3/nm indicated that the transparent dielectric selectively absorbed the surface plasmon polariton wave and the sensitivity of the waveguide structure designed in this paper has high stability for the refractive index of the main waveguide cavity. Obvious Fano resonance could be observed with the increase of refractive index for silicon cavity. Among the four dielectrics, silicon and water are suitable for studying Fano resonance and filter dielectrics.

2 citations

Journal ArticleDOI
10 Nov 2020

1 citations

References
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Journal ArticleDOI
Sajeev John1
TL;DR: A new mechanism for strong Anderson localization of photons in carefully prepared disordered dielectric superlattices with an everywhere real positive dielectrics constant is described.
Abstract: A new mechanism for strong Anderson localization of photons in carefully prepared disordered dielectric superlattices with an everywhere real positive dielectric constant is described. In three dimensions, two photon mobility edges separate high- and low-frequency extended states from an intermediate-frequency pseudogap of localized states arising from remnant geometric Bragg resonances. Experimentally observable consequences are discussed.

9,067 citations

Journal ArticleDOI
01 Mar 2007-Nature
TL;DR: The experimental observation of Anderson localization in a perturbed periodic potential is reported: the transverse localization of light caused by random fluctuations on a two-dimensional photonic lattice, demonstrating how ballistic transport becomes diffusive in the presence of disorder, and that crossover to Anderson localization occurs at a higher level of disorder.
Abstract: One of the most interesting phenomena in solid-state physics is Anderson localization, which predicts that an electron may become immobile when placed in a disordered lattice. The origin of localization is interference between multiple scatterings of the electron by random defects in the potential, altering the eigenmodes from being extended (Bloch waves) to exponentially localized. As a result, the material is transformed from a conductor to an insulator. Anderson's work dates back to 1958, yet strong localization has never been observed in atomic crystals, because localization occurs only if the potential (the periodic lattice and the fluctuations superimposed on it) is time-independent. However, in atomic crystals important deviations from the Anderson model always occur, because of thermally excited phonons and electron-electron interactions. Realizing that Anderson localization is a wave phenomenon relying on interference, these concepts were extended to optics. Indeed, both weak and strong localization effects were experimentally demonstrated, traditionally by studying the transmission properties of randomly distributed optical scatterers (typically suspensions or powders of dielectric materials). However, in these studies the potential was fully random, rather than being 'frozen' fluctuations on a periodic potential, as the Anderson model assumes. Here we report the experimental observation of Anderson localization in a perturbed periodic potential: the transverse localization of light caused by random fluctuations on a two-dimensional photonic lattice. We demonstrate how ballistic transport becomes diffusive in the presence of disorder, and that crossover to Anderson localization occurs at a higher level of disorder. Finally, we study how nonlinearities affect Anderson localization. As Anderson localization is a universal phenomenon, the ideas presented here could also be implemented in other systems (for example, matter waves), thereby making it feasible to explore experimentally long-sought fundamental concepts, and bringing up a variety of intriguing questions related to the interplay between disorder and nonlinearity.

1,368 citations

Journal ArticleDOI
TL;DR: An intermediate regime is found in which the ballistic and localized components coexist while diffusive dynamics is absent and evidence is found for a faster transition into localization under nonlinear conditions.
Abstract: We experimentally investigate the evolution of linear and nonlinear waves in a realization of the Anderson model using disordered one-dimensional waveguide lattices. Two types of localized eigenmodes, flat-phased and staggered, are directly measured. Nonlinear perturbations enhance localization in one type and induce delocalization in the other. In a complementary approach, we study the evolution on short time scales of delta-like wave packets in the presence of disorder. A transition from ballistic wave packet expansion to exponential (Anderson) localization is observed. We also find an intermediate regime in which the ballistic and localized components coexist while diffusive dynamics is absent. Evidence is found for a faster transition into localization under nonlinear conditions.

792 citations

Journal ArticleDOI
TL;DR: Exploiting the low spatial coherence of specifically designed random lasers, researchers demonstrate speckle-free full-field imaging in the regime of intense optical scattering.
Abstract: Exploiting the low spatial coherence of specifically designed random lasers, researchers demonstrate speckle-free full-field imaging in the regime of intense optical scattering. Their results show that the quality of images generated from random-laser illumination is superior to those generated from spatially coherent illumination.

777 citations

Journal ArticleDOI
TL;DR: In this article, the authors review both theoretical and experimental advances in the recently emerged field of modulated photonic lattices and highlight a new type of modulation-induced light localization based on the defect-free surface waves.

401 citations