Large scale simulations in the realm of nanooptics (original) (raw)
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Large scale simulations in the realm of nanooptics
Integrated Optics: Devices, Materials, and Technologies XIV, 2010
The realm of nanooptics is usually characterized by the interaction of light with structures having relevant feature sizes much smaller than the wavelength. To model such problems, a large variety of methods exists. However, most of them either require a periodic arrangement of a unit cell or can handle only single entities. But there exists a great variety of functional
Light scattering by correlated disordered assemblies of nanoantennas
Applied Physics Letters, 2019
Optical nanoantennas are widely used to build absorbing metasurfaces with applications in photodetection, solar cells, and sensing. Most of the time, the nanoantennas are assembled as a periodic distribution, but there have been various works where disordered arrays are used, either to get rid of diffraction orders or due to a fabrication process that prevents any determined distribution. Here, we investigate both theoretically and experimentally the unavoidable scattering introduced by such disorders. By introducing a perturbation on the positions of 1D arrays of metal-insulator-metal (MIM) nanoantennas, the light is scattered rather than increasingly absorbed. The scattering occurs only in the plane of incidence and on a given spectral range. We show how this scattering can be manipulated from 0% to 55% of the incoming light.
Proceedings of the National Academy of Sciences, 2014
Many experimental systems consist of large ensembles of uncoupled or weakly interacting elements operating as a single whole; this is particularly the case for applications in nano-optics and plasmonics, including colloidal solutions, plasmonic or dielectric nanoparticles on a substrate, antenna arrays, and others. In such experiments, measurements of the optical spectra of ensembles will differ from measurements of the independent elements as a result of small variations from element to element (also known as polydispersity) even if these elements are designed to be identical. In particular, sharp spectral features arising from narrow-band resonances will tend to appear broader and can even be washed out completely. Here, we explore this effect of inhomogeneous broadening as it occurs in colloidal nanopolymers comprising selfassembled nanorod chains in solution. Using a technique combining finite-difference time-domain simulations and Monte Carlo sampling, we predict the inhomogeneously broadened optical spectra of these colloidal nanopolymers and observe significant qualitative differences compared with the unbroadened spectra. The approach combining an electromagnetic simulation technique with Monte Carlo sampling is widely applicable for quantifying the effects of inhomogeneous broadening in a variety of physical systems, including those with many degrees of freedom that are otherwise computationally intractable. photonics | FDTD | random sampling | stochastic
Simulation of Solar Cells with Integration of Optical Nanoantennas
Nanomaterials, 2021
The evolution of nanotechnology has provided a better understanding of light-matter interaction at a subwavelength scale and has led to the development of new devices that can possibly play an important role in future applications. Nanoantennas are an example of such devices, having gained interest in recent years for their application in the field of photovoltaic technology at visible and infrared wavelengths, due to their ability to capture and confine energy of free-propagating waves. This property results from a unique phenomenon called extraordinary optical transmission (EOT) where, due to resonant behavior, light passing through subwavelength apertures in a metal film can be transmitted in greater orders of magnitude than that predicted by classical theories. During this study, 2D and 3D models featuring a metallic nanoantenna array with subwavelength holes coupled to a photovoltaic cell are simulated using a Finite Element Tool. These models present with slight variations bet...
Modeling and Computation of Nano Optics
2016
This work is devoted to a review of our recent studies in the modeling and compu3 tation of nano optical devices. Motivated by technological advances at nano scale, to quantitatively 4 understand the mechanism and improve the designing, we make an effort to model nano optical 5 systems involving multiple physical processes across different time and space scales, and develop 6 multiscale and adaptive numerical methods for simulation. Challenges on rigorous analysis of the 7 models and algorithms are also discussed. 8
GSvit — An open source FDTD solver for realistic nanoscale optics simulations
Computer Physics Communications, 2021
Surface and volume imperfections can significantly affect the performance of nanoscale or microscale devices used in photonics, optoelectronics or scientific instrumentation. In this article we present an open source software package for Finite-Difference Time-Domain electromagnetic field calculations suitable for calculations on graphics cards. Its special features include handling realistic models of imperfect nanoscale objects, such as treatment of arbitrary geometries including addition of random roughness to any geometrical object. The method is compared to conventional optical approach represented by Rayleigh-Rice theory. Practical applicability is demonstrated using a calculation of variation of field enhancement at proximity of a rough nanoscale antenna and rough particle scattering. It is shown that such approach can be namely useful in the areas where many repeated calculations are necessary, e.g. when studying how the optical response of nanoscale objects can vary when they are rough.
Toward Ultimate Nanoplasmonics Modeling
ACS Nano, 2014
Advances in the field of nanoplasmonics are hindered by the limited capabilities of simulation tools in dealing with realistic systems comprising regions that extend over many light wavelengths. We show that the optical response of unprecedentedly large systems can be accurately calculated by using a combination of surface integral equation (SIE) method of moments (MoM) formulation and an expansion of the electromagnetic fields in a suitable set of spatial wave functions via fast multipole methods. We start with a critical review of volume versus surface integral methods, followed by a short tutorial on the key features that render plasmons useful for sensing (field enhancement and confinement). We then use the SIE-MoM to examine the plasmonic and sensing capabilities of various systems with increasing degrees of complexity, including both individual and interacting gold nanorods and nanostars, as well as large random and periodic arrangements of ∼1000 gold nanorods. We believe that the present results and methodology raise the standard of numerical electromagnetic simulations in the field of nanoplasmonics to a new level, which can be beneficial for the design of advanced nanophotonic devices and optical sensing structures.
Optimization of the optical properties of nanostructures through fast numerical approaches
SPIE Proceedings, 2014
Surface nanostructuration is an important challenge for the optimization of light trapping in solar cell. We present simulations on both the optical properties and the efficiency of micro pillars-MPs-or nanocones-NCs-silicon based solar cells together with measurements on their associated optical absorption. We address the simulation using the Finite Difference Time Domain method, well-adapted to deal with a periodic set of nanostructures. We study the effect of the period, the bottom diameter, the top diameter, and the height of the MPs or NCs on the efficiency, assuming that one absorbed photon induces one exciton. This allows us to give a kind of abacus involving all the geometrical parameters of the nanostructured surface with regard to the efficiency of the associated solar cell. We also show that for a given ratio of the diameter over the period, the best efficiency is obtained for small diameters. For small lengths, MPs are extended to NCs by changing the angle between the bottom surface and the vertical face of the MPs. The best efficiency is obtained for an angle of the order of 70. Finally, nanostructures have been processed and allow comparing experimental results with simulations. In every case, a good agreement is found. V
A Novel Analysis for Light Patterns in Nano Structures
IEEE Photonics Journal
Nano antennas have a significant role in photonic nanodevices due to the ability of concentrating radiation in a small space region. The confined fields present a high sensitivity to the used materials in that regions. The electromagnetic wave models of nanoantennas usually operate in the frequency domain. However, electromagnetic wave models in the time domain are just as important and more advantageous, for example, in light pulses propagation. In this article, a new stochastic method based on the ray model of light in absorbing media is presented and light patterns on a target near a nanoantenna are obtained. The optical properties of the materials are described by their complex refractive index. When dealing with photons in the time domain, this formulation allows the calculation of the probability of a given photon movement. Different patterns, obtained with the new method, are compared with a Finite Element Tool ones, leading to model validation. The simulated structure included an aperture nanoantenna. With this method, the results show the light confinement and the extraordinary optical transmission phenomenon, meaning some photons on the target are refracted and re-transmitted by the metal. Thus, the output beam is more intense than the transmitted directly by the apertures. Index Terms-Extraordinary optical transmission, light patterns, nano arrays, nano antennas, optical devices. I. INTRODUCTION N OWADAYS, nanotechnology is an emergent area with several applications. For example, optical devices such as nano arrays or nanoantennas are commonly used in photonic circuits. The physical principle is based on light-matter interaction [1], [2], [3], [4]. The classical theories, assuming that metals reflect all incident light, can adequately represent light-metal interaction for radio and microwave frequencies. However, they no longer apply to optical frequencies and at nano scale. In 1998, Ebbesen discovered a new optical phenomenon, named extraordinary optical transmission (EOT), which is a resonant
Rigorous simulations of emitting and non-emitting nano-optical structures
In the next decade, several applications of nanotechnology will change our lives. LED lighting is about to replace the common light bulb. The main advantages are its energy efficiency and long lifetime. LEDs can be much more efficient, when part of the emitted light that is currently trapped in the device, could be radiated out of the device. Other devices such as photovoltaic solar cells and biosensors can also be made more efficient and cheaper. LEDs, solar cells and biosensors have in common that they consist of small structures of the order of the wavelength of the light. With such small structures light can be manipulated in a special way. In this thesis, we describe a method to calculate the interaction of light with these small structures. It is shown that an efficient LED which radiates light, can be treated as a solar cell that absorbs as much of the incoming light as possible. On this so-called reciprocity principle, which was discovered by Henrik Antoon Lorentz, a very efficient computational optimalisation method can be based. With this method existing designs of for example LEDs can be made more efficient iteratively. This thesis shows optimized designs of LEDs, solar cells and biosensors.