PECULIAR PROPERTIES OF ELECTROMAGNETIC RADIATION PROPAGATION IN PHOTONIC CRYSTALLINE METAL-DIELECTRIC SYSTEMS BASED ON OPALS

The article studies the propagation of electromagnetic waves in metal-dielectric systems based on opals. We revealed anomalous transmission and absorption of light by hybrid plasmon- photonic layered heterostructures associated with the excitation of surface plasmon polaritons propagating along the metal-dielectric interface. The position of maxima in the reflection spectra of nanocomposites, obtained by filling the opal matrix with metal by the electrothermodiffusion method, is explained by the Bragg diffraction, and the asymmetric form of the spectral curves is attributed to the Fano resonance.

DETERMINATION OF THE ACOUSTO-OPTICAL DEFLECTOR PARAMETERS FOR A LASER-RADIATION ROCKET GUIDANCE SYSTEM

The work is devoted to the development of an acousto-optic deflector for a laser-beam guidance system (LLSN) of missiles. LLSN is used in semiautomatic portable missile systems to destroy hostile targets of various types. An analysis of the methods for constructing such systems has shown that the most promising devices with pulse-code modulation using semiconductor pulsed lasers. The article provides a diagram and describes the principle of operation of the LLSN with pulse-code modulation. A problematic issue in the implementation of such a system is the development of a device for deflecting a laser beam, through which the missile is guided to a target. Scanning mechanical devices that are currently in use have a complex design, significant dimensions and weight, and limited performance. The article proposes to use an acousto-optic deflector to deflect the laser beam within the information field of the guidance system, which is devoid of these disadvantages, since it replaces the mechanical scanning device with an electronic one. The purpose of the article is to determine the main parameters of the acousto-optical deflector. The article discusses the principle of operation of an acousto-optic deflector. It is noted that glasses based on germanium chalcogenides, in particular, glass with the composition Ge2.17As39.13S58.70, have especially low values of acoustic losses (α <1 dB / cm). The largest deflection angle of the laser beam will be observed with Bragg diffraction. Relationships are given that can be used to determine the main characteristics of the deflector: the angle of deflection of the laser beam, the modulation frequency of the acoustic wave, resolution, speed, and others. When using the above ratios for the typical parameters of the existing guidance system, the values of the indicated characteristics are calculated.

Hyperentanglement teleportation through external momenta states

The conventional teleportation protocol requires a state entangled in only one degree of freedom, while hyperteleportation requires more than single degree of freedom to complete the task. The hyperteleportation schematics are demonstrated only for the photonic systems, where in the present paper we extend the idea to a hyperteleportation protocol involving the atomic internal and external states. The protocol is deterministically engineered through resonant and off-resonant Atomic Bragg Diffraction (ABD) involving two-level neutral atoms under standard cavity-QED working environment. Moreover, the longer interaction time Bragg's regime with well separated transverse momenta states as an output of the neutral atoms guarantees the high enough engineering fidelities with reduced decoherence rates. The experimental parameters for the demonstration of the proposed scheme are also elucidated briefly describing the optimistic feasibility for the experimental execution of the proposed schematics.

Rapid Screening of Butyl Paraben Additive in Toner Sample by Molecularly Imprinted Photonic Crystal

In consideration of the endocrine disrupting effects caused by the butyl paraben (BP), a portable visual sensor has been developed based on the photonic crystal and molecular imprinting technology for the rapid screen of BP in toner sample, which is a type of aqueous cosmetic to soften the face skin. By integrating the self-reporting and molecular recognition properties, the molecular imprinting photonic crystal (MIPC) sensor can display obvious color changes regularly according to the concentration of BP. Based on the “color guide”, the content of BP in toner sample can be estimated directly with the naked eye. In addition, the Bragg diffraction spectrum of MIPC can red shift linearly with the increase of the concentration of BP in sample solution with correlation coefficient as 0.9968. The quantitative determination of BP can be achieved through the optical fiber spectrometer with detection limit as 0.022 mmol·L−1. With good selectivity, this MIPC film can recognize BPs against the complex sample matrix, showing a standard addition recovery of 107% for the real samples.

2D scanning system of the acousto-optical deflector with high diffraction efficiency

The paper considers advantages and special features of an acousto-optic method for the development of a functional device for spatial and temporal control of laser light and reports results of investigations to create a two-directional acousto-optic laser scanner with diffraction efficiency as high as 80 percent or better. An acousto-optic deflector on a paratellurite crystal operating under the Bragg diffraction condition with a lithium niobate piezoelectric acoustic transducer was developed and tested experimentally. The results of this work can serve as a basis for the development of prototype functional acousto-optic devices for spatial and temporal control of laser light and their application to create laser television images.

Photonic dualism of icosahedral quasicrystals

Here we report on fabrication of 3D submicron-size dielectric icosahedral quasicrystals and show a photonic dualism of these structures. Relying on far-field measurements, we found pronounced patterns of unconventional Bragg diffraction, which indicates the existence of multiple photonic pseudogaps.

Rocking Curve Imaging Investigation of the Long-Range Distortion Field between Parallel Dislocations with Opposite Burgers Vectors

We observe a long-range distortion field between parallel dislocations with opposite Burgers vectors in a platelet-shaped single crystal of 4H-SiC with a low dislocation density (~103 cm/cm3). This distortion field is in the µradian range when the distance D between dislocations is in the ~50–250 µm range. We were able to characterise this weak distortion field through Rocking Curve Imaging (RCI), a highly sensitive Bragg diffraction imaging technique using monochromatic synchrotron radiation. From the experimental images, we generate maps of the angle of maximum reflectance (“peak position”) that provide a measurement of the local lattice orientation. Deviations from the crystal matrix orientation are associated with the long-range distortion field around dislocations. Between parallel dislocations with opposite Burgers vectors, this distortion does not decay to zero but towards a constant value α. We propose a simple model considering the angular parameter α characterising the distortion. This model indicates that α should roughly vary as 1/D. This appears to be in fair agreement with our experimental data.

New developments including X-ray standing waves in the dynamical Bragg diffraction program of X-ray Server

X-ray Server (https://x-server.gmca.aps.anl.gov) is a collection of programs for online modelling of X-ray diffraction and scattering. The dynamical diffraction program is the second most popular Server program, contributing 34% of total Server usage. It models dynamical X-ray diffraction from strained crystals and multilayers for any Bragg-case geometry including grazing incidence and exit. This paper reports on a revision of equations used by the program, which yields ten times faster calculations in most use cases, on implementing calculations of X-ray standing waves and on adding new options for modelling diffraction from monolayers.

Effect of Dispersion-Enhanced Sensitivity in a Two-Mode Optical Waveguide with an Asymmetric Diffraction Grating

Analysis of trends in the development of silicon photonics shows the high efficiency regarding the creation of optical sensors. The concept of bimodal sensors, which suggests moving away from the usual paradigm based only on single-mode waveguides and using the inter-mode interaction of guided optical waves in a two-mode optical waveguide, is developed in the present paper. In this case, the interaction occurs in the presence of an asymmetric periodic perturbation of the refractive index above the waveguide surface. Such a system has unique dispersion properties that lead to the implementation of collinear Bragg diffraction with the mode number transformation, in which there is an extremely high dependence of the Bragg wavelength on the change in the refractive index of the environment. This is called the “effect of dispersion-enhanced sensitivity”. In this paper, it is shown by numerical calculation methods that the effect can be used to create optical sensors with the homogeneous sensitivity higher than 3000 nm/RIU, which is many times better than that of sensors in single-mode waveguide structures.