Optical Necklace States in Anderson Localized 1D Systems

Bertolotti, Jacopo; Gottardo, S.; Wiersma, Diederik S.; Ghulinyan, Mher; Pavesi, L.

doi:10.1103/physrevlett.94.113903

Cited by 200 publications

(166 citation statements)

References 24 publications

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“…The spatially localized defect inside the W1 waveguide that localized the mode can be considered similar to the perturbation successfully introduced to create high Q heterostructure PhC cavities. 31 A second kind of localized states has been identified as necklace states, 32,33 for instance at = 1490.3 nm and = 1491.84 nm: their particularity is to exhibit an intensity pattern that begins at the input of the waveguide but abruptly stops at a random position. Their Q factors do not exceed 10 4 .…”

Section: B Frequency Scanning Of the Modesmentioning

confidence: 99%

Light transport regimes in slow light photonic crystal waveguides

et al. 2009

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The dispersive properties of waves are strongly affected by inevitable residual disorder in man-made propagating media, in particular in the slow wave regime. By a direct measurement of the dispersion curve in k space, we show that the nature of the guided modes in real photonic crystal waveguides undergoes an abrupt transition in the vicinity of a band edge. Such a transition that is not highlighted by standard optical transmission measurement, defines the limit where k can be considered as a good quantum number. In the framework of a mean-field theory we propose a qualitative description of this effect and attribute it to the transition from the "dispersive" regime to the diffusive regime. In particular we prove that a scaling law exists between the strength of the disorder and the group velocity. As a result, for group velocities v g smaller than c / 25 the diffusive contribution to the light transport is predominant. In this regime the group velocity v g loses its relevance and the energy transport velocity v E is the proper light speed to consider.

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Section: B Frequency Scanning Of the Modesmentioning

confidence: 99%

Light transport regimes in slow light photonic crystal waveguides

et al. 2009

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“…This is exactly the case of mode A and mode B, which have a larger spatial overlap respect to the previous case (BC). The time evolution of the A and B wavelengths reported in Figure 5 observed in 1D-systems [37] and predicted for higher dimensions [23].…”

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confidence: 99%

Engineering of light confinement in strongly scattering disordered media

et al. 2014

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The ability to mold the flow of light at the wavelength scale has been largely investigated in photonic-crystal-based devices, a class of materials in which the propagation of light is driven by interferences between multiply Bragg scattered waves and whose energy dispersion is described by a photonic band diagram [1]. Light propagation in such structures is defined by Bloch modes, which can be engineered by varying the structural parameters of the material [2][3][4]. In disordered media, both the direction and phase of the propagating waves are randomized in a complex manner, making any attempt to control light propagation particularly challenging. Disordered media are currently investigated in several contexts, ranging from the study of collective multiple scattering phenomena [5,6] to cavity quantum electrodynamics and random lasing [7,8], to the possibility to provide efficient solutions in renewable energy [9], imaging [10], and spectroscopy-based applications [11]. Transport in such systems can be described in terms of photonic modes, or quasi-modes, which exhibit characteristic spatial profiles and spectra [12,13]. In diffusive systems, these modes are spatially and spectrally overlapping while in the regime of Anderson localization, they become spatially and spectrally-isolated [14]. Unlike Bloch modes in periodic systems, the precise formation of photonic modes in a single realization of the disorder is unpredictable.Control over light transport can be obtained by shaping the incident wave to excite only a specific part of the modes available in a given system [15][16][17][18]. For fully exploiting the potential of disordered systems, however, a mode control is needed. It was shown 3 theoretically that isolated modes could be selectively tuned and possibly coupled to each other by a local fine modification of the dielectric structure [19,20].In this Article, we demonstrate experimentally the ability to fully control the spectral properties of an individual photonic mode in a two-dimensional disordered photonic structure [21], in a wavelength range that is relevant for photonic research driven applications. A statistical analysis of individual spatially-isolated random photonic modes is performed by multi-dimensional near-field imaging, leading to a detailed determination of intensity fluctuations, decay lengths and mode volumes. We then demonstrate that individual modes can be fine-tuned either by near-field tip perturbation or by local sub-micrometer-scale oxidation of the semiconductor slab [22]. The resonant frequency of a selected mode is gradually shifted until it is in perfect spectral superposition with the frequency of other two modes, located a few micrometers apart and spatially overlapping with the tuned mode. On spectral resonance, we observe frequency crossing and anti-crossing behaviours, respectively, the latter indicating mode interaction. This provides the experimental proof-of- (e) and (f), respectively). The main difference between the two spectra normalized to the average intensity i...

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“…Thus, the width of F 1 (x/ The scaling of t D , shown as the blue squares, is similar to the scaling of t 1 for diffusive waves L)/F 1 (1/2) would indicate the dominance of the transport through either isolated states or necklace states for localized waves. The existence of both single peaked localized states and multiply peaked necklace states has been observed in layered media 46 , single mode waveguides 47 , natural materials 48 , and can be created in multimode optical fiber with mode coupling 49 . It is also of great interest to explore the disposition of energy within thin anisotropic scattering media, of importance in biomedical research 50 .…”

Section: Discussionmentioning

confidence: 99%

Diffusion in Translucent Media

Genack

Shi

2018

Conference on Lasers and Electro-Optics

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Diffusion is the result of repeated random scattering. It governs a wide range of phenomena from Brownian motion, to heat flow through window panes, neutron flux in fuel rods, dispersion of light in human tissue, and electronic conduction. It is universally acknowledged that the diffusion approach to describing wave transport fails in translucent samples thinner than the distance between scattering events such as are encountered in meteorology, astronomy, biomedicine, and communications. Here we show in optical measurements and numerical simulations that the scaling of transmission and the intensity profiles of transmission eigenchannels have the same form in translucent as in opaque media. Paradoxically, the similarities in transport across translucent and opaque samples explain the puzzling observations of suppressed optical and ultrasonic delay times relative to predictions of diffusion theory well into the diffusive regime.

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Optical Necklace States in Anderson Localized 1D Systems

Cited by 200 publications

References 24 publications

Light transport regimes in slow light photonic crystal waveguides

Light transport regimes in slow light photonic crystal waveguides

Engineering of light confinement in strongly scattering disordered media

Diffusion in Translucent Media

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