Novel compact magnetless isolator based on a magneto-optical garnet material

A compact magnetless isolator for optical communication systems based on a ring resonator with an outer layer made of silicon and an inner layer made of a magneto-optical material that does not require an external magnet to keep its magnetization saturated is suggested. Three-dimensional computational simulations of the device performed with the full-wave electromagnetic solver COMSOL Multiphysics show that the insertion loss and isolation levels are about −1.9 dB and −23 dB, respectively, thus confirming the feasibility of the isolator. An analytical model of the device based on the temporal coupled-mode theory method has been formulated and there is a good agreement between the analytical and simulation results. Since it does not require a magnetization scheme based on permanent magnets or electromagnets as conventional isolators do, the presented isolator is much more compact, with a footprint at least one order of magnitude smaller in comparison with other isolator designs known from the literature, and this feature makes the suggested device an ideal candidate for optical circuits with very high integration density

Dispositivos de controle não recíprocos baseados em cristais fotônicos para utilização na faixa de frequências óptica

The study of the photonic crystals technology is being performed by many research groups, mostly because of their many practical applications. Photonic crystal structures are comprised by materials with different refractive indexes, periodically arranged in one, two or three dimensions. They can be employed in the construction of passive photonic devices, for use in optical systems. Photonic crystal based devices have reduced dimensions when compared to the traditionally employed ones, favoring an increase on the component integration density in optical systems. On the basis of studies related to the symmetry groups of several geometrical configurations of photonic crystals and by performing many computational simulations, eight unprecedented passive devices were developed, with new operating principles. Five switches, one circulator, one nonreciprocal power divider and one multifunctional device were designed, on the basis of photonic crystals technology. The designed devices can be used, for example, in the next generation optical computers, as well as in optical communication systems.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoO estudo da tecnologia de cristais fotônicos vem sendo realizado por muitos grupos de pesquisa, principalmente por conta das muitas aplicações práticas deles. Cristais fotônicos são estruturas constituídas por materiais com diferentes índices de refração, arranjados periodicamente em uma, duas ou três dimensões. Podem ser empregados na construção de dispositivos fotônicos passivos, para utilização em sistemas ópticos. Dispositivos baseados em cristais fotônicos têm dimensões reduzidas, quando comparados aqueles tradicionalmente empregados, favorecendo o aumento na densidade de integração de componentes de sistemas ópticos. Tendo como base a realização de estudos sobre os grupos de simetrias de várias configurações geométricas de cristais fotônicos e a execução de uma série de simulações computacionais, foram desenvolvidos oito dispositivos passivos inéditos, com novos princípios de operação. Cinco chaves, um circulador, um divisor de potência não recíproco e um dispositivo multifuncional foram projetados, com base na tecnologia de cristais fotônicos. Os dispositivos desenvolvidos podem ser utilizados, por exemplo, em computadores ópticos da próxima geração, bem como em sistemas de comunicações ópticas

Magnetless optical circulator based on an iron garnet with reduced magnetization saturation

A three-port circulator for optical communication systems comprising a photonic crystal slab made of a magneto-optical material in which an magnetizing element is not required to keep its magnetic domains aligned is suggested for the first time. By maximizing the incorporation of europium to its molecular formula, the magneto-optical material can remain in the saturated magnetic state even in the absence of an external DC magnetic field. Two-and three-dimensional simulations of the device performed with full-wave electromagnetic solvers based on the finite element method demonstrate that, at the 1550 nm wavelength, the insertion loss, isolation, and reflection levels are equal to or better than −1 dB, −14 dB, and −20 dB, respectively. Since its operation does not require an electromagnet or a permanent magnet, the suggested circulator is much more compact, being able to reach footprints in the range of three orders of magnitude smaller, when compared to other circulator designs referred to in the literature and the presented results can be useful for the design of other nonreciprocal devices with reduced dimensions for optical communication systems

Theoretical Study of Plasmonically Induced Transparency Effect in Arrays of Graphene-Based Double Disk Resonators

Abstract In this paper, we consider coupled disk-shaped resonators separated by a thin dielectric substrate that can be used as frequency-tunable filters or as electromagnetic switches in the terahertz frequency band. The two disks are electromagnetically coupled and resonate with dipole plasmonic modes. By using a Temporal Coupled-Mode Theory based approach, we show how to analytically calculate the frequency response of such structures.The analytical results are in good agreement with those obtained from computational simulations based on the finite element method

Photonic integrated circulators based on iron garnets without external magnetization

A new compact optical circulator based on a photonic crystal made of a triangular lattice of air holes etched in a magneto-optical material that does not require an external DC magnetic field to keep its saturated magnetic state is presented. The design has a threefold rotational symmetry and it consists of three single-mode waveguides and one resonator supporting dipole resonances introduced in the photonic crystal structure. Computational simulations of the circulator demonstrate that, at the 1.55 μm wavelength, the insertion losses are about-1 dB, while the isolation and reflection levels are about-15 dB and-24 dB, respectively

Theoretical study of plasmonically induced transparency effect in arrays of graphene-based double disk resonators

In this paper, we consider coupled disk-shaped resonators separated by a thin dielectric substrate that can be used as frequency-tunable filters or as electromagnetic switches in the terahertz frequency band. The two disks are electromagnetically coupled and resonate with dipole plasmonic modes. By using a Temporal Coupled-Mode Theory based approach, we show how to analytically calculate the frequency response of such structures.The analytical results are in good agreement with those obtained from computational simulations based on the finite element method.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorUFPA - Universidade Federal do ParáNeste trabalho, consideramos ressonadores em forma de disco acoplados separados por um substrato dielétrico fino que pode ser usado como filtros sintonizáveis ​​por freqüência ou como interruptores eletromagnéticos na faixa de freqüência terahertz. Os dois discos são acoplados eletromagneticamente e ressoam com os modos de plasma dipolo. Utilizando uma abordagem baseada na Teoria do Modo Acoplado Temporal, mostramos como calcular analiticamente a resposta de freqüência de tais estruturas. Os resultados analíticos estão em boa concordância com aqueles obtidos de simulações computacionais baseadas no método dos elementos finitos.PORTELA, G. M. T.; DMITRIEV, V. A.; OLIVEIRA, C. B. Universidade Federal do Par

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