Semitransparent Mirror Research Articles

Semi-transparent boundary in Lee–Wick electrodynamics

In this paper, we investigate certain aspects of Lee–Wick electrodynamics near a semitransparent planar mirror. Specifically, we derive the modified propagator for the Lee–Wick gauge field in the presence of the mirror and conduct a detailed analysis of the interaction energy and the interaction force that arise between the mirror and a stationary point-like charge. We demonstrate that there are several peculiarities in this interaction compared to the results obtained for Maxwell electrodynamics. Our focus is on the divergences mitigated by the Podolsky mass term.

Quantum Coherent Feedback Control With Photons

The purpose of this paper is to study two-photon dynamics induced by the coherent feedback control of a cavity quantum electrodynamics (cavity-QED) system coupled to a waveguide. In this set-up, the two-level system in the cavity can work as a photon source, and the photon emitted into the waveguide can re-interact with the cavity-QED system many times after the transmission and reflection in the waveguide, during which the feedback can tune the number of the photons in and out of the cavity. We analyze the dynamics of two-photon processes in this coherent feedback network in two scenarios: the continuous mode coupling scheme and the discrete periodic mode coupling scheme between the waveguide and cavity. The difference of these coupling schemes is due to their relative scales and the number of semi-transparent mirrors for coupling. Specifically, in the continuous mode coupling scheme, the generation of two-photon states is influenced by the length of the feedback loop by the waveguide and the coupling strength between the waveguide and the cavity-QED system. By tuning the length of the waveguide and the coupling strength, we are able to generate two-photon states efficiently. In the discrete periodic mode coupling scheme, the Rabi oscillation in the cavity can be stabilized and there are no notable two-photon states in the waveguide.

Particle production by a relativistic semitransparent mirror of finite size and thickness

Production of massless scalar particles by a relativistic semitransparent mirror of finite transverse size and longitudinal thickness in (1+3)D flat spacetime is studied. The derived particle spectrum formula is applied to two specific trajectories. One is the gravitational collapse trajectory invoked in (1+1)D perfectly reflecting moving mirror literature to mimic Hawking radiation, and the other is the plasma mirror trajectory proposed to be realizable in future experiments. It is found that the finiteness of the transverse size leads to diffraction, while the nontrivial thickness amplifies the production rate. We also estimated the particle yield as ∼3000\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim 3000$$\\end{document} in a 20-day data acquisition based on the parameters invoked in the proposed AnaBHEL experiment.

A RECONFIGURABLE METASURFACE IN THE FORM OF A FABRY-PÉROT RESONATOR, INVOLVING SEMI-TRANSPARENT MIRRORS AND A NONLINEAR DIELECTRICINSERT

Subject and Purpose. The paper is aimed at suggesting ways for implementing electromagnetic devices that would involve a nonlinear dielectric inside the structure for concentrating electromagnetic field within it at relatively low intensities of the excitation field. A representative example is offered by a Fabry-Pérot resonator with semi-transparent mirrors and a nonlinear dielectric inside. Methods and Methodology. The paper presents a fundamentally new approach to controlling the frequency response of a metasurface, and a method for protecting electronic modules from high excitation powers. The method is based on the use of nonlinear properties of a Fabry-Pérot "resonator-capacitor" containing a nonlinear dielectric in its volume. Thus, we propose a method for creating spatial filters and antenna protecting fairings capable of active reconfiguration. Results. Analysis of the results has shown that by changing the voltage across the resonator-capacitor plates it is possible to control the degree of electromagnetic field localization in the resonator volume. The frequency response of the metasurface based on the Fabry-Pérot resonator with a nonlinear dielectric inside can be reconfigured by changing the voltage applied to the resonator mirrors. The advantages provided by electrical control of the frequency-selective characteristics include an increased efficiency and possibility of integrating digitally controllable systems into antennas. Conclusions. The use of a Fabry-Pérot "resonator-capacitor"model, with a nonlinear dielectric inside, in the capacity of a reconfigurable metasurface, else as a power limiter in a variety of devices, has sufficient prospects for application in microwave transmitting systems. A special area of application for the reconfigurable Fabry-Pérot resonators is creation of broadband receive antenna systems for direction- finding. In essence, the proposed Fabry-Pérot resonator is a reflective antenna array with an ability to exhibit, conceal or alter its electrodynamic properties according to a certain algorithm. This opens up prospects for its application in "friend-or-foe" recognition systems, reflective beacons, navigation systems, etc.

Unstable confocal resonator with external flat semi-transparent mirror for additional feedback

Main characteristics (mode structure of power loss, divergence of resonant radiation) of a three-mirror laser cavity with additional feedback are theoretically studied in the Fresnel approximation on the basis of the Fox-Lee integral equation. The resonator consists of two spherical mirrors, which form an unstable confocal resonator, and a flat semi-transparent mirror, which is installed outside the reference unstable resonator perpendicular to its optical axis. The flat coupling mirror returns part of the radiation back inside the resonator. The level of additional feedback is determined by the reflection coefficient of the flat mirror and the position of the mirror along the optical axis of the resonator. Variation of these parameters makes it possible to control the transparency of the three-mirror resonator over a wide range, up to values close to zero. Results of this paper can be used in the development of high-power lasers with wide aperture (Fresnel numbers of ∼100) on the basis of low-gain active media.

Gaussian beam propagation in a Lorentz-violating vacuum in the presence of a semi-transparent mirror

In this paper we study the propagation of structured optical scalar beams in a Lorentz-violating (LV) vacuum parametrized by a constant 4-vector u μ and in the presence of a semi-transparent mirror. The two bosonic degrees of freedom of the electromagnetic field can be described by a LV extension of the massless scalar field theory, whose LV part is characterized by the term (u · ∂ϕ)2. The mirror at a surface Σ is modelled by a delta-type potential in the Lagrange density for the LV scalar field, i.e. λ δ(Σ)ϕ 2, where the parameter λ controls the degree of transparency of the mirror. Using Green’s function techniques, we investigate the propagation of a Gaussian beam in the presence of a mirror which is perpendicular to the propagation direction and for two particular choices of the background 4-vector: parallel and perpendicular to the propagation direction. To quantify the Lorentz-violating effects we introduce the fidelity as a measurement of the closeness of the propagated field distribution with respect to that in the conventional vacuum. In the absence of the mirror (λ = 0) the fidelity is found to be close to one, and hence LV effects are quite small. However in the presence of the mirror, there are regions where the fidelity drops to zero, thus implying that LV effects could be clearly differentiated from the propagation in vacuum. Within the paraxial approximation we determine analytically the LV effects upon the Rayleigh range, the radius of the beam, the Gouy phase and the radius of curvature of the wavefronts. We discuss possible scenarios where our results could apply, by using optically transparent multiferroic materials, which offer unprecedented opportunities to tailor structured beam propagation, as well as to simulate an LV vacuum.

Dispersion Managed Mode-Locking in All-Fiber Polarization-Maintaining Nd-Doped Laser at 920 nm

We present a comprehensive study of dispersion managed ultrashort-pulse generation in Nd-doped polarization maintaining all-fiber laser at a 920 nm wavelength. We implement a linear laser scheme with a chirped fiber Bragg grating (CFBG) serving as a semitransparent mirror and semiconductor saturable absorber mirror (SESAM) as a mode-locker and as a second non-transparent mirror. Complete 1064 nm emission filtering is ensured by 920/1064 wavelength division multiplexer. The dispersion compensation by CFBG was sufficient to reach anomalous net dispersion in the shortest laser scheme allowing us to investigate mode-locking regimes in the −0.05 ps <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ÷ 0.24 ps <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> net dispersion range by varying the length of the passive fiber. With this approach we demonstrate high order harmonic mode-locking at dispersion closer to zero and large energy span near-parabolic shape single pulse operation in anomalous dispersion regime. The investigation is supported by numerical simulations used to optimize the laser resonator design and to investigate intracavity pulse evolution.

Solving integral equations in free space with inverse-designed ultrathin optical metagratings.

As standard microelectronic technology approaches fundamental limitations in speed and power consumption, novel computing strategies are strongly needed. Analogue optical computing enables the processing of large amounts of data at a negligible energy cost and high speeds. Based on these principles, ultrathin optical metasurfaces have been recently explored to process large images in real time, in particular for edge detection. By incorporating feedback, it has also recently been shown that metamaterials can be tailored to solve complex mathematical problems in the analogue domain, although these efforts have so far been limited to guided-wave systems and bulky set-ups. Here, we present an ultrathin Si metasurface-based platform for analogue computing that is able to solve Fredholm integral equations of the second kind using free-space visible radiation. A Si-based metagrating was inverse-designed to implement the scattering matrix synthesizing a prescribed kernel corresponding to the mathematical problem of interest. Next, a semitransparent mirror was incorporated into the sample to provide adequate feedback and thus perform the required Neumann series, solving the corresponding equation in the analogue domain at the speed of light. Visible wavelength operation enables a highly compact, ultrathin device that can be interrogated from free space, implying high processing speeds and the possibility of on-chip integration.

Антенная решетка Ku-диапазона частот на основе резонатора Фабри-Перо

The work is devoted to the development and study of the antenna array based on Fabry-Perot cavity in the radio band. The antenna array element in the form of a Fabry-Perot cavity with circular polarization is proposed, the semitransparent mirror of the cavity is realized in the form of a two-layer frequency-selective surface (FFS). A power divider based on thin waveguides to feed the antenna array with size 2x8 was developed. А model of the antenna array was manufactured. The power divider is made by laser cutting of sheet aluminum, semitransparent resonator layer is made by photolithography. The total efficiency of the antenna array was about 50% in the 5% frequency band with a VSWR of no more than 1.5.

Depth of field and resolution-enhanced integral imaging display system.

Depth of field (DOF) and resolution are mutually restricted in integral imaging (II) display. To overcome the trade-offs, we propose an II display system that simultaneously enhances the DOF and resolution. The system consists of a transmissive mirror device (TMD), a semi-transparent mirror (STM), and two II display units. Each II display unit consists of a 4K display screen and a micro-lens array (MLA). Benefiting from the parallel placement of the TMD and the STM, two central depth planes are reconstructed, which effectively enhances the DOF. Meanwhile, the resolution in the overlapping DOF region is increased to two times due to the interpolation of the light field information from two II display units. The impact of the distance between the two II display units and the TMD on the 3D image quality is analyzed. In geometric optics, a distance between the II two display units and the TMD is optimized to eliminate ghost images. In wave optics, a distance is optimized to eliminate 3D pixel gaps by exploiting the diffraction effect of the TMD. Both the geometric and wave optics are considered simultaneously to obtain a high-quality 3D image without ghost images and 3D pixel gaps. A DOF and resolution-enhanced II display system is developed, and the experimental results verify its feasibility.

P‐7.20: Depth‐enhanced Integral Imaging 3D Display System

A depth-enhance integral imaging (InIm) 3D display system is proposed. Two InIm 3D displays that are placed vertically and be used in the proposed system by combining a transmissive mirror device (TMD) and a semi-transparent mirror (STM) to enhance the depth. Due to the distance between the two InIm 3D displays and the TMD is different, so the 3D display proposed achieves the extension of depth of field (DOF). The experimental results demonstrate the validity of our proposed system.

Semi-transparent boundaries in CPT-even Lorentz violating electrodynamics

Some aspects of the nonbirefringent CPT-even gauge sector of the Standard Model Extension (SME), in the vicinity of a semi-transparent mirror, are investigated in this paper. We first consider a model where the Lorentz symmetry breaking is caused by a single background vector vμ, and we obtain perturbative results up to second order in vμ. Specifically, we compute the modified propagator for the gauge field due to the presence of the mirror and we analyze the corresponding interaction between the mirror and a stationary point-like charge. We show that when the charge is placed in the vicinity of the mirror, a spontaneous torque emerges, which is a new effect with no counterpart in Maxwell electrodynamics. We also compare these results with the corresponding ones obtained for the Lorentz violating scalar field theory. As expected, in the limiting case of perfect mirrors, we recover the interaction found via the image method. Finally, we discuss how we can extend these results for a more general Lorentz violating background.

Locally acting mirror Hamiltonians

Photons, i.e. the basic energy quanta of monochromatic waves, are highly non-localized and occupy all available space in one dimension. This non-local property can complicate the modelling of the quantized electromagnetic field in the presence of optical elements that are local objects. Therefore, in this paper, we take an alternative approach and quantize the electromagnetic field in position space. Taking into account the negative- and the positive-frequency solutions of Maxwell's equations, we construct annihilation operators for highly localized field excitations with bosonic commutator relations. These provide natural building blocks of wave packets of light and enable us to construct locally acting interaction Hamiltonians for two-sided semi-transparent mirrors.

Formation of beams with nonuniform polarisation of radiation in a cw waveguide terahertz laser

A method for obtaining non-Gaussian light beams with azimuthal field polarisation in a waveguide quasi-optical cavity is described. The method is based on the employment of polarisation-selective diffraction structures as laser mirrors. Efficient excitation of such beams at the output from an optically pumped waveguide HCOOH laser (λ = 0.4326 mm) with an inhomogeneous reflecting input and semitransparent output mirrors is confirmed theoretically and experimentally.

Dynamical Casimir effect in nonlinear vibrating cavities

Nonlinear terms in the equations of motion can induce secularly growing loop corrections to correlation functions. Recently such corrections were shown to affect the particle production by a nonuniformly moving ideal mirror. We extend this conclusion to the cases of ideal vibrating cavity and single semitransparent mirror. These models provide natural IR and UV scales and allow a more accurate study of the loop behavior. In both cases we confirm that two-loop correction to the Keldysh propagator quadratically grows with time. This growth indicates a breakdown of the semiclassical approximation and emphasizes that bulk nonlinearities in the dynamical Casimir effect cannot be neglected for large evolution times.

Dansyl-Labelled Ag@SiO2 Core-Shell Nanostructures—Synthesis, Characterization, and Metal-Enhanced Fluorescence

The present work describes synthesis, characterization, and use of a new dansyl-labelled Ag@SiO2 nanocomposite as an element of a new plasmonic platform to enhance the fluorescence intensity. Keeping in mind that typical surface plasmon resonance (SPR) characteristics of silver nanoparticles coincide well enough with the absorption of dansyl molecules, we used them to build the core of the nanocomposite. Moreover, we utilized 10 nm amino-functionalized silica shell as a separator between silver nanoparticles and the dansyl dye to prevent the dye-to-metal energy transfer. The dansyl group was incorporated into Ag@SiO2 core-shell nanostructures by the reaction of aminopropyltrimethoxysilane with dansyl chloride and we characterized the new dansyl-labelled Ag@SiO2 nanocomposite using transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). Additionally, water wettability measurements (WWM) were carried out to assess the hydrophobicity and hydrophilicity of the studied surface. We found that the nanocomposite deposited on a semitransparent silver mirror strongly increased the fluorescence intensity of dansyl dye (about 87-fold) compared with the control sample on the glass, proving that the system is a perfect candidate for a sensitive plasmonic platform.

Improvements of resolution of light field imaging based on four-dimensional optical framing via a semi-transparent mirror.

A simple light field imaging system is proposed, which could improve the resolution of light field imaging and enhance the signal-to-noise ratio of the result image. In the experiment, the light field imaging system consists of a single CCD with a microlens array and a semi-transparent mirror. The Fourier slice theorem has been used to transform the four-dimensional (4D) light field information into an infinite number of two-dimensional (2D) slices. With the use of the semi-transparent mirror, the high spatial resolution image can be reconstructed on the terminal sensor. The proposed method can not only reduce the aliasing defocus degree in the imaging process but also improve the slice image resolution to meet the requirement of image definition.

METHODS FOR ESTIMATING THE INTERNAL NOISES IN AUTO COLLIMATING DEVICES

Methods for estimating the internal noises in auto collimating devices are proposed. These devices are designed for measuring of angular shifting of an object with mirror surface, able to make shifts in certain range. Auto collimating method for measuring of angles is one of the high accurate methods for solving of unique technological problems. The accuracy in angular measuring through auto columniation in laboratory conditions reaches ten parts of the second. Classification of the existing photoelectric devices, their optical schemes, main metrological characteristics and working principle are exemplified in [1, 4, 6] and others. The objective of this research is the analysis of the internal light noises in AC for measuring angular shifts of the mirror surface object, which could move freely in restricted. Generally, auto collimators (AC) consists of auto collimating lens, scale, and source of light, condenser and analyzer of visible area. The scale, together with the source of light and the photo electric analyzer are placed in the focal plane of the lens and could be separated with semitransparent mirror. Having in mind the requirements of the overall dimensions and the tendency of making them smaller, the constructor has a choice of selecting a scale, analyzer and AC lens.

Mirrors and field sources in a Lorentz-violating scalar field theory

In this paper we consider classical effects in a model for a scalar field incorporating Lorentz symmetry breaking due to the presence of a single background vector vμ coupled to its derivative. We investigate of the interaction energy between stationary steady sources concentrated along parallel branes with an arbitrary number of dimensions, and derive from this study some physical consequences. For the case of the scalar dipole we show the emergence of a nontrivial torque, which is a distinctive sign of the Lorentz violation. We also investigate a similar model in the presence of a semi-transparent mirror. For a general relative orientation between the mirror and the vμ, we are able to perform calculations perturbatively in vμ up to second order, and we also present exact results specific cases. For all these configurations, the propagator for the scalar field and the interaction force between the mirror and a point-like field source are computed. It is shown that the image method is valid in our model for the Dirichlet's boundary condition, and we argue that this is a non-trivial result. We also show the emergence of a torque on the mirror depending on its orientation with respect to the Lorentz violating background: this is a new effect with no counterpart in theories with Lorentz symmetry in the presence of mirrors.

Linear scattering off a dynamically controlled nanosphere-mirror plasmonic antenna on a fiber taper.

A quartz-tuning-fork shear-force microscope was used to demonstrate the gap size dependency of the resonance frequency for a nanosphere-mirror plasmonic antenna. The nanosphere was mounted at the end of a fiber taper scanning probe. A semi-transparent silicon film mirror was used to couple evanescent fields from incident light with the plasmonic antenna using an inverted optical microscope. The plasmon resonance spectra were acquired with a 0.4 nm-step gap size tuning resolution, and were confirmed by finite-difference time-domain simulations. The proposed technique provides a dynamic approach to tuning and detecting distance-dependent localized surface plasmon resonance with a sub-nanometer step resolution.