arXiv subjects

Andrey E. Miroshnichenko

Publications and source records attributed to Andrey E. Miroshnichenko.

87 records · Page 5Linked to original sources

arXiv2009

Reversible nonreciprocity in photonic structures infiltrated with liquid crystals

We demonstrate how to achieve reversible nonreciprocal optical response in a periodic photonic structure with a pair of defects, one of them being a nonlinear liquid crystal defect layer. The twin defect layers structure is symmetric at low intensity and becomes asymmetric above a power threshold corresponding to the optical reordering of the liquid crystal. We show that nonreciprocal effects can be reversed by changing the wavelength as a consequence of the defect mode dependent light localization inside the structure.

physics.optics↗

arXiv2009

Mach-Zehnder-Fano interferometer

We introduce a concept of the Mach-Zehnder-Fano interferometer by inserting a cavity exhibiting Fano resonance into a conventional interferometer. By employing the scattering-matrix approach, we demonstrate that the transmission is sensitive to a position of the cavity such that an asymmetric structure exhibits a series of narrow resonances with almost perfect reflection. We discuss how to implement this novel geometry in two-dimensional photonic crystals and use direct numerical simulations to demonstrate novel regimes of the resonant transmission and reflection.

physics.optics↗

arXiv2009

Fano resonances in nanoscale structures

Nowadays nanotechnology allows to scale-down various important devices (sensors, chips, fibres, etc), and, thus, opens up new horizon for their applications. Nevertheless, the efficiency most of them is still based on the fundamental physical phenomena, such as resonances. Thus, the understanding of the resonance phenomena will be beneficial. One of the well-known examples is the resonant enhancement of the transmission known as Breit-Wigner resonances, which can be described by a Lorentzian function. But, in many physical systems the scattering of waves involves propagation along different paths, and, as a consequence, results in interference phenomena, where constructive interference corresponds to resonant enhancement and destructive interference to resonant suppression of the transmission. Recently, a variety of experimental and theoretical work has revealed such patterns in different branches of physics. The purpose of this Review is to demonstrate that this kind of resonant scattering is related to the Fano resonances, known from atomic physics. One of the main features of the Fano resonances is the asymmetric profile. The asymmetry comes from the close coexistence of resonant transmission and resonant reflection. Fano successfully explained such a phenomenon in his seminal paper in 1961 in terms of interaction of a discrete (localized) state with a continuum of propagation modes. It allows to describe both resonant enhancement and resonant suppression in a unified manner. All of these properties can be demonstrated in the frame of a very simple model, which will be used throughout the Review to show that resonant reflections observed in different complex systems are indeed closely related to the Fano resonances.

cond-mat.mtrl-sci↗

arXiv2009

Non-Rayleigh limit of the Lorenz-Mie solution and suppression of the scattering by the spheres of negative refractive index

We study light scattering by spheres made of negative refractive index materials. We demonstrate that scattering efficiency of the light does not always obey the well-known Rayleigh's law $Q_{\rm sca}\sim1/λ^4$ for small values of size parameter, but could be wavelength independent $Q_{\rm sca}\sim const$, or even increase with the wavelength as $Q_{\rm sca}\simλ^2$. In addition, it is found that spheres with radius comparable with the input wavelength may exhibit suppression of the scattering in any directions, particularly in forward one. It can be considered as analogues of Brewster's angles for spheres.

physics.optics↗

arXiv2008

Low-threshold bistability of slow light in photonic-crystal waveguides

We analyze the resonant transmission of light through a photonic-crystal waveguide side coupled to a Kerr nonlinear cavity, and demonstrate how to design the structure geometry for achieving bistability and all-optical switching at ultra-low powers in the slow-light regime. We show that the resonance quality factor in such structures scales inversely proportional to the group velocity of light at the resonant frequency and thus grows indefinitely in the slow-light regime. Accordingly, the power threshold required for all-optical switching in such structures scales as a square of the group velocity, rapidly vanishing in the slow-light regime.

physics.optics↗

arXiv2008

Coupled-resonator-induced reflection in photonic-crystal waveguide structures

We study the resonant transmission of light in a coupled-resonator optical waveguide interacting with two nearly identical side cavities. We reveal and describe a novel effect of the coupled-resonator-induced reflection (CRIR) characterized by a very high and easily tunable quality factor of the reflection line, for the case of the inter-site coupling between the cavities and the waveguide. This effect differs sharply from the coupled-resonator-induced transparency (CRIT) -- an all-optical analogue of the electromagnetically-induced transparency -- which has recently been studied theoretically and observed experimentally for the structures based on micro-ring resonators and photonic crystal cavities. Both CRIR and CRIT effects have the same physical origin which can be attributed to the Fano-Feshbach resonances in the systems exhibiting more than one resonance. We discuss the applicability of the novel CRIR effect to the control of the slow-light propagation and low-threshold all-optical switching.

physics.optics↗

arXiv2007

All-optical switching and multistability in photonic structures with liquid crystal defects

We demonstrate that one-dimensional photonic crystals with pure nematic liquid-crystal defects can operate as all-optical switching devices based on optical orientational nonlinearities of liquid crystals. We show that such a periodic structure is responsible for a modulated threshold of the optical Fréedericksz transition in the spectral domain, and this leads to all-optical switching and light-induced multistability. This effect has no quasi-statics electric field analogue, and it results from nonlinear coupling between light and a defect mode.

cond-mat.soft↗

arXiv2007

Fano resonances at light scattering by an obstacle

It is shown that elastic resonance scattering of light by a finite-size obstacle with weak dissipation is analogous to quantum scattering by a potential with quasi-discrete levels and exhibits Fano resonances. Localized plasmons (polaritons), exited in the obstacle by the incident light, are equivalent to the quasi-discrete levels, while the radiative decay of these excitations plays exactly the same role as tunnelling from the quasi-discrete levels for the quantum problem. Mie scattering of light by a spherical particle and an exactly solvable discrete model with nonlocal coupling simulating wave scattering in systems with reduced spatial dimensionality are discussed as examples.

cond-mat.other↗

arXiv2006

Localized modes and bistable scattering in nonlinear network junctions

We study the properties of junctions created by crossing of N identical branches of linear discrete networks. We reveal that for N>2 such a junction creates a topological defect and supports two types of spatially localized modes. We analyze the wave scattering by the junction defect and demonstrate nonzero reflection for any set of parameters. If the junction is nonlinear, it is possible to achieve the maximum transmission for any frequency by tuning the intensity of the scattering wave. In addition, near the maximum transmission the system shows the bistable behaviour.

physics.optics↗

arXiv2006

All-optical switching, bistability, and slow-light transmission in photonic crystal waveguide-resonator structures

We analyze the resonant linear and nonlinear transmission through a photonic crystal waveguide side-coupled to a Kerr-nonlinear photonic crystal resonator. Firstly, we extend the standard coupled-mode theory analysis to photonic crystal structures and obtain explicit analytical expressions for the bistability thresholds and transmission coefficients which provide the basis for a detailed understanding of the possibilities associated with these structures. Next, we discuss limitations of standard coupled-mode theory and present an alternative analytical approach based on the effective discrete equations derived using a Green's function method. We find that the discrete nature of the photonic crystal waveguides allows a novel, geometry-driven enhancement of nonlinear effects by shifting the resonator location relative to the waveguide, thus providing an additional control of resonant waveguide transmission and Fano resonances. We further demonstrate that this enhancement may result in the lowering of the bistability threshold and switching power of nonlinear devices by several orders of magnitude. Finally, we show that employing such enhancements is of paramount importance for the design of all-optical devices based on slow-light photonic crystal waveguides.

physics.optics↗

arXiv2006

Light-induced multistability and Freedericksz transition in nematic liquid crystals

We study light transmission through a homeotropically oriented nematic liquid crystal cell and solve self-consistently a nonlinear equation for the nematic director coupled to Maxwell's equations. We demonstrate that above a certain threshold of the input light intensity, the liquid-crystal cell changes abruptly its optical properties due to the light-induced Freedericksz transition, demonstrating multistable hysteresis-like dependencies in the transmission. We suggest that these properties can be employed for tunable all-optical switching photonic devices based on liquid crystals.

physics.optics↗

arXiv2006

Tunable all-optical switching in periodic structures with liquid-crystal defects

We suggest that tunable orientational nonlinearity of nematic liquid crystals can be employed for all-optical switching in periodic photonic structures with liquid-crystal defects. We consider a one-dimensional periodic structure of Si layers with a local defect created by infiltrating a liquid crystal into a pore, and demonstrate, by solving numerically a system of coupled nonlinear equations for the nematic director and the propagating electric field, that the light-induced Freedericksz transition can lead to a sharp switching and diode operation in the photonic devices.

physics.optics↗

arXiv2005

Engineering Fano resonances in discrete networks

We study transmission properties of discrete networks composed of linear arrays coupled to systems of N side defects, and demonstrate the basic principles of the resonant scattering management through engineering Fano resonances. We find exact solutions for the wave transmission coefficient and reveal the conditions for the perfect reflections and transmissions due to either destructive or constructive interferences. We associate these reflections and transmissions with Fano resonances, and demonstrate how they can be tuned by introducing nonlinear defects into the network.

cond-mat.other↗

arXiv2005

Sharp bends in photonic crystal waveguides as nonlinear Fano resonators

We demonstrate that high transmission through sharp bends in photonic crystal waveguides can be described by a simple model of the Fano resonance where the waveguide bend plays a role of a specific localized defect. We derive effective discrete equations for two types of the waveguide bends in two-dimensional photonic crystals and obtain exact analytical solutions for the resonant transmission and reflection. This approach allows us to get a deeper insight into the physics of resonant transmission, and it is also useful for the study and design of power-dependent transmission through the waveguide bends with embedded nonlinear defects.

cond-mat.mtrl-sci↗

arXiv2004

Nonlinear Fano resonance and bistable wave transmission

We consider a discrete model that describes a linear chain of particles coupled to a single-site defect with instantaneous Kerr nonlinearity. We show that this model can be regarded as a nonlinear generalization of the familiar Fano-Anderson model, and it can generate the amplitude depended bistable resonant transmission or reflection. We identify these effects as the nonlinear Fano resonance, and study its properties for continuous waves and pulses.

cond-mat.soft↗