Université de Fribourg

Unequivocal signatures of the crossover to Anderson localization in realistic models of disordered quasi-one-dimensional materials

Lopez-Bezanilla, Alejandro ; Froufe-Pérez, Luis S. ; Roche, Stephan ; Sáenz, Juan José

In: Physical Review B, 2018, vol. 98, no. 23, p. 235423

The only unequivocal known criterion for single-parameter scaling Anderson localization relies on the knowledge of the full conductance statistics. To date, theoretical studies have been restricted to model systems with symmetric scatterers, hence lacking universality. We present an in-depth statistical study of conductance distributions P(g), in disordered ‘micrometer-long’ carbon...

Université de Fribourg

Band gap formation and Anderson localization in disordered photonic materials with structural correlations

Froufe-Pérez, Luis S. ; Engel, Michael ; Sáenz, Juan José ; Scheffold, Frank

In: Proceedings of the National Academy of Sciences, 2017, vol. 114, no. 36, p. 9570–9574

Disordered dielectric materials with structural correlations show unconventional optical behavior: They can be transparent to long-wavelength radiation, while at the same time have isotropic band gaps in another frequency range. This phenomenon raises fundamental questions concerning photon transport through disordered media. While optical transparency in these materials is robust against...

Université de Fribourg

Fluctuations of the electromagnetic local density of states as a probe for structural phase switching

Sousa, N. de ; Sáenz, Juan José ; Scheffold, Frank ; García-Martín, A. ; Froufe-Pérez, Luis S.

In: Physical Review A, 2016, vol. 94, no. 4, p. 043832

We study the statistics of the fluorescence decay rates for single quantum emitters embedded in a scattering medium undergoing a phase transition. Under certain circumstances, the structural properties of the scattering medium explore a regime in which the system dynamically switches between two different phases. While in that regime the light-scattering properties of both phases are hardly...

Université de Fribourg

Role of short-range order and hyperuniformity in the formation of band gaps in disordered photonic materials

Froufe-Pérez, Luis S. ; Engel, Michael ; Damasceno, Pablo F. ; Muller, Nicolas ; Haberko, Jakub ; Glotzer, Sharon C. ; Scheffold, Frank

In: Physical Review Letters, 2016, vol. 117, no. 5, p. 053902

We study photonic band gap formation in two-dimensional high-refractive-index disordered materials where the dielectric structure is derived from packing disks in real and reciprocal space. Numerical calculations of the photonic density of states demonstrate the presence of a band gap for all polarizations in both cases. We find that the band gap width is controlled by the increase in...

Université de Fribourg

Magneto-Optical Activity in High Index Dielectric Nanoantennas

Sousa, N. de ; Froufe-Pérez, Luis S. ; Sáenz, Juan José ; García-Martín, A.

In: Scientific Reports, 2016, vol. 6, p. 30803

The magneto-optical activity, namely the polarization conversion capabilities of high- index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system....

Université de Fribourg

High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide

Marichy, Catherine ; Muller, Nicolas ; Froufe-Pérez, Luis S. ; Scheffold, Frank

In: Scientific Reports, 2016, vol. 6, p. 21818

Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold...

Université de Fribourg

Localized magnetic plasmons in all-dielectric $\ensuremath{\mu}<0$ metastructures

Paniagua-Domínguez, R. ; Froufe-Pérez, Luis S. ; Sáenz, J. J. ; Sánchez-Gil, J. A.

In: Physical Review B, 2015, vol. 91, no. 23, p. 235120

Metamaterials are known to exhibit a variety of electromagnetic properties nonexisting in nature. We show that an all-dielectric (nonmagnetic) system consisting of deep-subwavelength, high-permittivity resonant spheres possesses effective negative magnetic permeability (dielectric permittivity being positive and small). Due to the symmetry of the electromagnetic wave equations in classical...

Université de Fribourg

Controlling dispersion forces between small particles with artificially created random light fields

Brügger, Georges ; Froufe-Pérez, Luis S. ; Scheffold, Frank ; Sáenz, Juan José

In: Nature Communications, 2015, vol. 6, p. 7460

Appropriate combinations of laser beams can be used to trap and manipulate small particles with optical tweezers as well as to induce significant optical binding forces between particles. These interaction forces are usually strongly anisotropic depending on the interference landscape of the external fields. This is in contrast with the familiar isotropic, translationally invariant, van der Waals...

Université de Fribourg

Speckle fluctuations resolve the interdistance between incoherent point sources in complex media

Carminati, R. ; Cwilich, G. ; Froufe-Pérez, Luis S. ; Sáenz, J. J.

In: Physical Review A, 2015, vol. 91, no. 2, p. 023807

We study the fluctuations of the light emitted by two identical incoherent point sources in a disordered environment. The intensity-intensity correlation function and the speckle contrast, obtained after proper temporal and configurational averaging, encode the relative distance between the two sources. This suggests the intriguing possibility that intensity measurements at only one point in a...