Magneto-optical switching in microcavities based on a TGG defect sandwiched between periodic and disordered one-dimensional photonic structures

The employment of magneto-optical materials to fabricate photonic crystals gives the unique opportunity to achieve optical tuning by applying a magnetic field. In this study we have simulated the transmission spectrum of a microcavity in which the Bragg reflectors are made with silica (SiO2) and yttria (Y2O3) and the defect layer is made with TGG (Tb3Ga5O12). We show that the application of an external magnetic field results in a tuning of the defect mode of the microcavity. In the simulations we have considered the wavelength dependence of the refractive indexes and the Verdet constants of the materials. A tuning of the defect mode of about 22 nm with a magnetic field of 5 T, at low temperature (8 K), is demonstrated. Furthermore, we discuss the possibility to tune a microcavity with disordered photonic structures as reflectors. In the presence of the magnetic field such microcavity shows a shift of resonances in a broad range of wavelengths. This study presents a method of contactless optical tuning.Comment: 8 pages, 4 figure

Light-induced switching in pDTE - FICO 1D photonic structures

We propose the design of 1D photonic crystals and microcavities in which fluorine-indium codoped cadmium oxide (FICO) nanocrystal based layers and layers of diarylethene-based polyester (pDTE) are alternated or embedded in a microcavity. The irradiation with UV light results in two different behaviours: i) it dopes the FICO nanocrystals inducing a blue shift of their plasmonic resonances; ii) it changes the real part of the refractive index of the photochromic pDTE polymer. These two behaviours are combined in the proposed photonic structures and can be useful for switchable filters and cavities for light emission.Comment: 9 pages, 5 figure

A probabilistic model of the electron transport in films of PbSe nanocrystals arranged in a cubic lattice

The fabrication of nanocrystal (NC) films, starting from colloidal dispersion, is a very attractive topic in condensed matter physics community. NC films can be employed for transistors, light emitting diodes, laser, and solar cells. For this reason the understanding of the film conductivity is of major importance. In this paper we describe a probabilistic model that allow to predict the conductivity of the NC films, in this case of a cubic lattice of Lead Selenide NCs. The model is based on the hopping probability between NCs show a comparison with experimental data reported in literature.Comment: 5 pages, 4 figure

An energy window study of light transmission-disorder relationship in 1D photonic structures

While the light transmission of photonic crystals is characterized by the photonic band gap, the one of disordered photonic structures is typified by a multiplicity of transmission depths. The total transmission over a range of wavelengths is related to the width of such range, but also to the type of disorder. Less homogeneous disordered structures transmit more light than the ordered counterpart regardless of the wavelengths range width. More homogeneous disordered structures transmit more light than the ordered counterpart only above a certain value of the width. We studied this behaviour with a statistical analysis over 5000 permutations of structures for each wavelength width and for each homogeneity degree (Shannon-Wiener index).Comment: 8 pages, 4 figure

Materialist Premises in Hobbes and Kropotkin for Antipodean Conclusions: The State of War and the Mutual Aid

A methodological similarity between Thomas Hobbes and Pëtr Kropotkin is the intention to elucidate a theoretical foundation to a broad audience, in the sense that they are willing to popularize a clear description of the reality and a subsequent political view. To do so, they use a scientific method, deductive (starting from empirical observations) in the case of Hobbes, inductive-deductive in the case of Kropotkin. Kropotkin also underlines the educational value of the scientific method. Although they both start their argumentations from a materialist ontology, Hobbes and Kropotkin conjecture two completely different states of nature. Hobbes describes the state of nature through the two famous metaphors homo homini lupus and bellum omnium contra omnes, while Kropotkin introduced the theory of mutual aid. Hobbes has been influenced by the scientific revolution initiated by Francis Bacon, one of his mentors, and Galileo Galilei. Kropotkin has been influenced by the ground-breaking writings of Charles Darwin together with a very fruitful Russian scientific environment. The disenchanted view of the human nature in Hobbes, a state of war due to the fact that everyone has rights on everything, helps him to legitimate sovereignty, while the positive view of human nature in Kropotkin, a spontaneous mutual aid among people in a community, helps him to legitimate anarchy. Therefore, the fascinating scientific methods of the two materialists Hobbes and Kropotkin to structure a solid political theory cannot neglect different views on human nature due to their historical contexts

Multilayer plasmonic photonic structures embedding photochromic molecules or optical gain molecules

We design photonic structures embedding different functional molecular systems of photochromic switching and lasing. We study the light absorption of two photochromic molecules and of 4,4'-bis[(N-carbazole)styryl]biphenyl (BSB-Cz) with density functional theory. For the photochromic diarylethene we derivate the refractive index with Kramers-Kronig relations and we design multilayer photonic structures alternating diarylethene with either poly vinyl carbazole or fluorine indium co-doped cadmium oxide (FICO) nanoparticlebased layers. For BSB-Cz we design a one-dimensional photonic crystal alternating BSB-Cz layers with $SiO_{2}$ layers and a microcavity embedding BSB-Cz between indium tin oxide (ITO) / FICO nanoparticle-based multilayers.Comment: 18 pages, 8 figure