Flexible Organometal Random Lasers

Disorder is emerging as a strategy for fabricating random laser sources with very promising materials, like perovskites, for which standard laser cavities are not effective, or too expensive. We need however different fabrication protocols and technologies for reducing the laser threshold and controlling its emission. Here we demonstrate an effectively solvent-engineered method for high-quality perovskite thin films on the flexible polyimide substrate. The fractal perovskite thin films exhibit excellent optical properties at room temperature and easily achieve lasing action without any laser cavity above room temperature with a low pumping threshold. The lasing action is also observed in curved perovskite thin films on the flexible substrates. The lasing threshold can be further reduced by increasing the local curvature, which modifies the scattering strengths of the bent thin film. We also show that the curved perovskite lasers are extremely robust with respect to repeated deformations. Because of the low spatial coherence, these curved random laser devices are efficient and durable speckle-free light sources for applications in spectroscopy, bio-imaging, and illumination.

Wang et al. in ACS Nano (2019)


See also …

Nonlinear localized waves in curved geometry
Lasing in curved geometry

Graphene oxide photonics

The successful exfoliation of graphite initiated new science in any research field and is employing a huge number of scientists in the world investigating chemical, structural, mechanical and optoelectrical; properties of the atomic-thick sheets of graphene and graphene oxide. Similarly to other carbon-based materials, graphene family have shown exceptional optical responses; and nowadays it is engineered to produce efficient photonic components. In this review we aim to summarize the main results in nonlinear optical response and fluorescence of graphene oxide; moreover, its laser printing is reviewed as a novel promising lithographic technique.

Neda Ghofraniha and Claudio Conti in Journal of Optics


See also …

Deep learning, living, random, optical, and – maybe – useful

In a recent paper, we demonstrated an optical deep neural network with a real living piece of brain tumor (a 3D “tumour model”). We think this is the first example of a hybrid living/photonic hardware: a sort of artificially intelligent device performing optical functions and detecting tumour morphodynamics (including the effect of chemotherapy)

Deep optical neural network by living tumour brain cells

Abstract: The new era of artificial intelligence demands large-scale ultrafast hardware for machine learning. Optical artificial neural networks process classical and quantum information at the speed of light, 
and are compatible with silicon technology, but lack scalability and need expensive manufacturing of many computational layers. New paradigms, as reservoir computing and the extreme learning machine, suggest that disordered and biological materials may realize artificial neural networks with thousands of computational nodes trained only at the input and at the readout. Here we employ biological complex systems, i.e., living three-dimensional tumour brain models, and demonstrate a random neural network (RNN) trained to detect tumour morphodynamics via
image transmission. The RNN, with the tumour spheroid 19 as a three-dimensional deep computational reservoir, performs programmed optical functions and detects cancer morphodynamics from laser-induced hyperthermia inaccessible by optical imaging. Moreover, the RNN quantifies the effect of chemotherapy inhibiting tumour growth. We realize a non-invasive smart probe for cytotoxicity assay, which is at least one order of magnitude more sensitive with respect to conventional imaging. Our random and hybrid photonic/living system is a novel artificial machine for computing and for the real-time investigation of tumour dynamics.

Authors: D. Pierangeli, V. Palmieri, G. Marcucci, C. Moriconi, G. Perini, M. De Spirito, M. Papi, C. Conti

https://arxiv.org/abs/1812.09311

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