Category: Random Lasers

MRS Fall Meeting 2018 (Boston): Tailored Disorder – Call for Papers

We are announcing the Tailored Disorder Symposium at the MRS (Material Research Society) Fall Meeting 2018

Disorder and perturbed periodicity in materials are in the process of becoming a vital research area that has started to show that optical media do not necessarily have to be regular. Photonic materials with deliberately introduced disorder in their respective geometries and compositions show interesting novel and tunable unforeseen properties. So far, countable scientific achievements have been reported in the areas of biology, materials science, nano-optics and -photonics that, however, already point towards a wealth of interesting effects with several applicative dimensions. This notion could be derived from the finding of structural disorder being often beneficial in nature and being useful as an engineering guide for the development of novel advanced optics and photonics devices. The general subject of structural disorder is rapidly emerging into an area of interdisciplinary scientific interest, which is however still in its infancy. Therefore, the purpose of this symposium is to bring together specialists from various scientific communities such as physics, biology and materials science and engineering to advance the structural disorder research area based on fundamental and applied research with emphasis on multidisciplinary approaches and fabrication routes. Contributions from the fields of theoretical, applied and computational physics, optics and photonics in biology, materials engineering and nano-patterning are encouraged. The development of novel approaches and design routes to realize tailored disorder in materials will be one of the main topics of the symposium. Presentations might include various patterning procedures including etching techniques, replica moulding, self-assembly, sol-gel procedures, solid state synthesis, soft lithography, layer-by-layer deposition with the focus on materials functions and properties.

Symposium organizers: Cordt Zollfrank, Claudio Conti, Hui Cao, Sushil Mujumdar

Download the  Call for Paper

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Lasing on nonlinear localized waves in curved geometry

The use of geometrical constraints exposes many new perspectives in photonics and in fundamental studies of nonlinear waves. By implementing surface structures in vertical cavity surface emitting lasers as manifolds for curved space, we experimentally study the impacts of geometrical constraints on nonlinear wave localization. We observe localized waves pinned to the maximal curvature in an elliptical-ring, and confirm the reduction in the localization length of waves by measuring near and far field patterns, as well as the corresponding energy-angle dispersion relation. Theoretically, analyses based on a dissipative model with a parabola curve give good agreement remarkably to experimental measurement on the reduction in the localization length. The introduction of curved geometry allows to control and design lasing modes in the nonlinear regime.

Kou-Bin Hong, Chun-Yan Lin, Tsu-Chi Chang, Wei-Hsuan Liang, Ying-Yu Lai, Chien-Ming Wu, You-Lin Chuang, Tien-Chang Lu, Claudio Conti, and Ray-Kuang Lee in Optics Express 25, 29068 (2017)

The Experimental Observation of Replica Symmetry Breaking in Random Lasers

Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics, and many other research fields. According to this theory, identical systems under identical conditions may reach different states and provide different values for observable quantities. This effect is known as Replica Symmetry Breaking and is theoretically revealed by the change in shape of the probability distribution function of an order parameter named the Parisi overlap.

Despite the profound implications in the new physics of complexity, a direct experimental evidence of the Replica Symmetry Breaking transition, in any field of research was never reported.

C. Conti and coworkers show that pulse-to-pulse fluctuations in random lasers, and  a direct measurement of the Parisi overlap, unveil a transition to a glassy light phase in random lasers compatible with a Replica Symmetry Breaking.

This is the first evidence of Replica Symmetry Breaking and the first direct measurement of the Parisi overlap.

Reference:

N. Ghofraniha, I. Viola, F. Di Maria, G. Barbarella, G. Gigli, L. Leuzzi and C. Conti reported on the first evidence of Replica Symmetry Breaking in Random Lasers by the direct measurement of the Parisi overlap distribution function (arXiv:1407.5428, Nature Communications 2015)

 

Biomimetic Random Lasers

Biometic random lasers

Living organisms have evolved well-adapted structures and
materials over geological eras. Through evolutional selection,
nature has devised effective solutions to all sorts of complicated
real-world problems and, following Leonardo Da Vinci,
humans have looked at nature to reach answers. The young
field of biomimetics has given rise to new technologies inspired
by nature’s strategy for materials and devices optimized from
the macroscale to the nanoscale.

Neda Ghofraniha, Luca La Volpe, Daniel Van Opdenbosch, Cordt Zollfrank, and Claudio Conti realize a novel random laser device made by biotemplated paper, and demonstrate the control of mode size and interaction. The work was published in Advanced Optical Materials.