A. Chabanov

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Papers by A. Chabanov

Optical limiter based on PT-symmetry breaking of reflectionless modes

Optica

The application of parity–time (PT) symmetry in optics, especially PT-symmetry breaking, has attr... more The application of parity–time (PT) symmetry in optics, especially PT-symmetry breaking, has attracted considerable attention as an approach to controlling light propagation. Here, we report optical limiting by two coupled optical cavities with a PT-symmetric spectrum of reflectionless modes. The optical limiting is related to broken PT symmetry due to light-induced changes in one of the cavities. Our experimental implementation involves a three-mirror resonator of alternating layers of ZnS and cryolite with a PT-symmetric spectral degeneracy of two reflectionless modes. The passive optical limiting is demonstrated by measurements of single 532 nm 6 ns laser pulses and thermo-optical simulations. At fluences below 10mJ/cm2, the multilayer exhibits a flattop passband at 532 nm. At higher fluences, laser heating combined with the thermo-optic effect in ZnS leads to cavity detuning and PT-symmetry breaking of the reflectionless modes. As a result, the entire multilayer structure quickl...

Intensity and Phase Distributions in the Transition from Ballistic to Diffusive Wave Propagation

Advances in Optical Imaging and Photon Migration

We report measurements of the intensity and phase distributions of microwave radiation transmitte... more

Light-induced optical switching in an asymmetric metal-dielectric microcavity with phase-change material

EPL (Europhysics Letters), 2019

We propose an infrared power switch based on an asymmetric high-Q microcavity incorporating a met... more We propose an infrared power switch based on an asymmetric high-Q microcavity incorporating a metallic nanolayer in close proximity to a layer made of a phase-change material (PCM). The microcavity is designed so that when the PCM layer is in the low-temperature phase, the metallic nanolayer coincides with a nodal plane of the resonant electric field component, to allow a high resonant transmittance. As the light intensity exceeds a certain threshold, lightinduced heating of the PCM layer triggers the phase transition accompanied by an abrupt change in its refractive index in the vicinity of the transition temperature. The latter results in a shift of the nodal plane away from the metallic nanolayer, rendering the entire microcavity highly reflective over a broad frequency range. The nearly binary nature of the PCM refractive index allows for the low-intensity resonant transmission over a broad range of ambient temperatures below the transition point.

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Pulsed laser deposition (PLD) employed in the fabrication of low temperature barium titanate (BTO) films on carbon fibers

2010 20th International Conference on Electronics Communications and Computers (CONIELECOMP), 2010

In order to explore the functionalization of wearable fabrics for power generation, barium titana... more In order to explore the functionalization of wearable fabrics for power generation, barium titanate (BTO) was deposited on nickel tape and on carbon fiber fabric employing pulsed laser deposition (PLD) methods under conditions normally not considered ideal to produce optimum ferroelectric properties, namely, at temperatures as low as 100 °C and under various oxygen partial pressures. The remnant charge polarization and film resistance properties were evaluated to determine the effect of the aforementioned deposition conditions. The C-V characterization indicates that the BTO films still retained ferroelectric properties in films produced at temperature as low as 200 °C, below which, the behavior was only paraelectric.

Photon localization in the time domain

Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies, 2004

ABSTRACT We observe weak and strong localization in the time domain as the nonexponential decay o... more

Impact of Weak Localization on Wave Dynamics: Crossover from Quasi-1D to Slab Geometry

Methods and Applications of Analysis, 2004

We study the dynamics of wave propagation in nominally diffusive samples by solving the Bethe-Sal... more We study the dynamics of wave propagation in nominally diffusive samples by solving the Bethe-Salpeter equation with recurrent scattering included in a frequency-dependent vertex function, which renormalizes the mean free path of the system. We calculate the renormalized time-dependent diffusion coefficient, D(t), following pulsed excitation of the system. For cylindrical samples with reflecting side walls and open ends, we observe a crossover in dynamics in the transformation from a quasi-1D to a slab geometry implemented by varying the ratio of the radius, R, to the length, L. Immediately after the peak of the transmitted pulse, D(t) falls linearly with a nonuniversal slope that approaches an asymptotic value for R/L ≫ 1. The value of D(t) extrapolated to t = 0, depends only upon the dimensionless conductance g for R/L ≪ 1 and upon kl 0 and L for R/L ≫ 1, where k is the wave vector and l 0 is the bare mean free path.

format_quoteThe renormalized diffusion coefficient values coincide with experimental results for moderate scattering strengths, validating theoretical predictions.format_quote

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Dynamics of Localized Waves

Photonic Metamaterials: From Random to Periodic, 2007

We have measured pulsed microwave transmission through quasi-1D samples with lengths up to three ... more We have measured pulsed microwave transmission through quasi-1D samples with lengths up to three localization lengths. For times approaching four times the diffusion time τD, transmission is diffusive in accord with the self-consistent theory of localization for the renormalized diffusion coefficient in space and frequency, D(z, Ω). For longer times, the transmission decay rate first agrees with and later falls increasingly below the self-consistent theory. Beyond the Heisenberg time, the decay rate approaches the predictions of a dynamic single parameter scaling model which reflects the decay of long-lived localized modes and converges to the results of 1D simulations.

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Statistical Approach to Photon Localization

Waves and Imaging through Complex Media, 2001

A statistical description of wave propagation in random media is necessary to characterize large ... more A statistical description of wave propagation in random media is necessary to characterize large fluctuations found in these samples. The nature of fluctuations is determined by the closeness to the localization transition. In the absence of inelastic processes, this can be specified, in many circumstances, by a single parameter — the ensemble average of the dimensionless conductance. As a result, the extent of localization can be determined by any of a wide variety of related statistical measurements. Among the quantities that most directly reflect key aspects of localization are the following: (i) the ensemble average of the dimensionless conductance, (ii) the degree of spatial correlation of intensity, (iii) the variances of the probability distribution of transmission quantities, such as the intensity, the total transmission, and the dimensionless conductance, and (iv) the ratio of the width to the spacing of modes of an open sample. We will emphasize the relationships between key statistical aspects of propagation in quasi-one-dimensional samples and the different impact of absorption upon these. We find that even in the presence of absorption, the extent of localization can be characterized by a single parameter — the variance of the total transmission normalized by its ensemble average. Measurements of fluctuations in intensity and total transmission of microwave radiation allow us to study photon localization in collections of dielectric spheres and in periodic metallic wire meshes containing metallic scatterers. We find in low-density collections of alumina spheres contained in a copper tube, at frequencies near the first Mie resonance, that the variance of normalized total transmission scales exponentially once it becomes greater than unity. When this parameter is large, transmission spectra are observed to be a series of narrow lines with widths that are smaller than the separation between peaks. These spectra have an extraordinarily wide intensity distribution and correspondingly large variance. These results demonstrate that the variance of normalized transmission serves as a powerful guide in the search for and characterization of photon localization.

Mesoscopic correlation in electromagnetic wave polarization

Frontiers in Optics, 2003

Strong Coupling of Terahertz Cyclotron Resonance with a One-Dimensional Photonic Crystal Cavity

Achieving strong light-matter interaction is essential for the study of cavity quantum electrodyn... more Achieving strong light-matter interaction is essential for the study of cavity quantum electrodynamics. In the ultrastrong coupling regime, where the ratio of the vacuum Rabi splitting to the transition frequency is close to or larger than one, intriguing quantum effects, e.g., the Bloch-Siegert Shift and interaction-dependent ground states, are expected to appear, due to the breakdown of the rotating wave approximation. Since this ratio increases with the transition wavelength, going to the terahertz (THz) range is promising for exploring new strong-coupling phenomena. Here, we experimentally demonstrate strong coupling between the cyclotron resonance of a high-mobility two-dimensional electron gas and a photonic defect mode in a one-dimensional (1D) THz photonic crystal (PC) cavity. Compared to THz cavities based on split-ring metamaterials, the 1D PC cavity exhibits a higher quality (Q) factor and lower loss, in spite of a larger mode volume. Our 1D PC cavities consist of quarter-wave intrinsic silicon / sapphire slabs and air gaps. The Q factor can be tuned in a wide range by changing the materials and the number of layers. An ultrathin modulation-doped GaAs quantum well is placed at the electric field maximum of the defect mode in the 1D THz PC cavity.

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Temperature dependence of ZnO thin film growth and its application to self-powered fabrics

2010 20th International Conference on Electronics Communications and Computers (CONIELECOMP), 2010

Zinc oxide thin films are becoming increasingly popular for their wide range of properties and th... more Zinc oxide thin films are becoming increasingly popular for their wide range of properties and the ability to deposit these films on organic substrates for applications such as biotemplating, OLEDs, or deposition on fabrics for functionalization purposes including power generation from the flexing and deformation of wearable textiles. However, since many fabrics and other organic substrates can not survive the typically high temperatures of thin film growth, it is important to characterize and understand the dependence of the properties of these films as a function of temperature deposition and subsequent thermal treatments. We report on the properties of zinc oxide thin films grown by Atomic Layer Deposition (ALD) and the dependence of surface roughness, film stress, surface energy and crystalline structure on deposition temperature.

Residual stress in zinc oxide thin films deposited by atomic layer deposition

The residual stress in a thin film can have an impact on the electrical and optical properties of... more The residual stress in a thin film can have an impact on the electrical and optical properties of the film. In addition, stress is an important consideration when incorporating the material into a microelectromechanical (MEMS) device as large unexpected stresses can cause such a device to fail. The residual stress in ZnO thin films prepared by atomic layer deposition was

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Integration of ferroelectric BaTiO3 on metallic Ni tapes for power generation

Ferroelectric BaTiO3 thin films were integrated directly on metallic Ni tapes by using pulsed las... more Ferroelectric BaTiO3 thin films were integrated directly on metallic Ni tapes by using pulsed laser for energy harvesting applications. Microstructure studies from x-ray diffraction and electron microscopy indicate that the as-grown BaTiO3 thin films have pure BaTiO3 crystal phase which consists of the crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm directly on the

Single-Channel Transport in Multichannel Disordered Systems

Frontiers in Optics 2011/Laser Science XXVII, 2011

ABSTRACT

Speckle Statistics of Localized Waves in Random Media

Frontiers in Optics 2010/Laser Science XXVI, 2010

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Photon Localization in Resonant Media

Physical Review Letters, 2001

We report measurements of microwave transmission over the first five Mie resonances of alumina sp... more We report measurements of microwave transmission over the first five Mie resonances of alumina spheres randomly positioned in a waveguide. Though precipitous drops in transmission and sharp peaks in the photon transit time are found near all resonances, measurements of transmission fluctuations show that localization occurs only in a narrow frequency window above the first resonance. There the drop in the photon density of states is found to be more pronounced than the fall in the photon transit time above the resonance, leading to a minimum in the Thouless number.

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Impact of Weak Localization in the Time Domain

Physical Review Letters, 2004

We find a renormalized ''time-dependent diffusion coefficient,'' Dt, for pulsed excitation of a n... more We find a renormalized ''time-dependent diffusion coefficient,'' Dt, for pulsed excitation of a nominally diffusive sample by solving the Bethe-Salpeter equation with recurrent scattering. We observe a crossover in dynamics in the transformation from a quasi-1D to a slab geometry implemented by varying the ratio of the radius, R, to the length, L, of the cylindrical sample with reflecting side walls and open ends. Immediately after the peak of the transmitted pulse, Dt falls linearly with a nonuniversal slope that approaches an asymptotic value for R=L 1. The value of Dt extrapolated to t 0 depends only upon the dimensionless conductance g for R=L 1 and only upon k' 0 for R=L 1, where k is the wave vector and ' 0 is the bare mean free path.

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Dynamic Correlation in Wave Propagation in Random Media

Physical Review Letters, 2004

We report time-resolved measurements of the statistics of pulsed transmission through quasi-onedi... more We report time-resolved measurements of the statistics of pulsed transmission through quasi-onedimensional dielectric media with static disorder. The normalized intensity correlation function with displacement and polarization rotation for an incident pulse of linewidth σ at delay time t is a function only of the field correlation function, which is identical to that found for steadystate excitation, and of κσ(t), the residual degree of intensity correlation at points at which the field correlation function vanishes. The dynamic probability distribution of normalized intensity depends only upon κσ(t). Steady-state statistics are recovered in the limit σ→0, in which κσ=0 is the steady-state degree of correlation.

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Intensity statistics of random signals in Gaussian noise

Physical Review E, 2009

The intensity statistics of signals in the presence of Gaussian noise is obtained by studying the... more The intensity statistics of signals in the presence of Gaussian noise is obtained by studying the model of a random signal plus a random phasor sum. The additive Gaussian noise is shown to result in a Bessel transform of the probability density of the signal intensity. The transformation of the intensity statistics can generally be applied to a mixture of independent random signals, one of which being a complex-valued Gaussian random process. It is used to retrieve intensity statistics of microwave pulsed transmission from Gaussian noise at long time delays.

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Statistics of the mesoscopic field

Physical Review E, 2005

We find in measurements of microwave transmission through quasi-1D dielectric samples for both di... more We find in measurements of microwave transmission through quasi-1D dielectric samples for both diffusive and localized waves that the field normalized by the square root of the spatially averaged flux in a given sample configuration is a Gaussian random process with position, polarization, frequency, and time. As a result, the probability distribution of the field in the random ensemble is a mixture of Gaussian functions weighted by the distribution of total transmission, while its correlation function is a product of correlators of the Gaussian field and the square root of the total transmission.

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