Спектры поглощения пробного сигнала и резонансной флуоресценции для излучателей при их взаимодействии с локальным окружением в прозрачных средах

The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong monochromatic cw laser. The sensitivity of absorption and emission optical spectroscopy method is compared for revealing the effects of the medium on individual emitters and their ensembles. Spectral curves were calculated for model emitters considering local field influence of a transparent dielectric medium and local electron-phonon interactions, which determined the response of the emitters to an external laser field and effective relaxation mechanisms. The calculation formalism is based on a semiclassical approach, while the relaxation processes associated with the phonon contribution are introduced phenomenologically with references to other studies.

Optical BPSK Modulation and Demodulation using Opti System Simulator

Fibre optics deals with study of propagation of light through transparent dielectric waveguides. The fibre optics is used for transmission of data from point to point location. Fibre optic systems currently used are most extensively as the transmission line between terrestrial hardwired systems. The carrier frequencies used in conventional systems had the limitations in handling the volume and rate of the data transmission. Greater the carrier frequency larger is the available bandwidth and information carrying capacity. This paper explains about Optical BPSK, where input data is converted to BPSK data which is optically modulated by optical modulator and transmitted through an optical fibre cable. The transmitted data and received data are compared in the end.

Dipole–Dipole Broadening in the Selective Reflection of an Intense Laser Beam from the Interface between a Transparent Dielectric and a Dense Resonance Gas

The dipole–dipole broadening of the spectrum of the selective reflection of intense resonance light from the interface between a transparent dielectric and a gas of the natural mixture of Rb isotopes has been studied experimentally. The case of a high gas density where the Doppler broadening can be neglected has been investigated. It has been shown that dipole–dipole broadening is reduced with increasing the number density of excited atoms. When the laser beam intensity is much higher than the saturation intensity of a resonance transition, a significant broadening due to the very high laser beam intensity has not been observed in the reflection spectrum from the transparent dielectric/gas interface. The observed intensity dependence of the spectral width has been explained by the quenching collisions of the excited atoms with the interface.

Omnidirectional Photonic Bandgap in Two-dimensional Photonic Quasicrystal Made of Near-Transparent Dielectric Material

Complete bandgap for all-dielectric photonic crystals in the microwave region can be obtained only by using high-contrast materials. This requires the usage of dielectric materials with high relative permittivity coefficient. In this paper, we study, both numerically and experimentally, a two-dimensional all-dielectric photonic quasicrystal made of polyurethane foam, which is considered in all microwave applications as a transparent material. The quasicrystal structure having an omnidirectional two-dimensional bandgap is mathematically generated by the direct inscription of Bragg’s peaks of the structure in the reciprocal space. The sample of the quasicrystal was manufactured on CNC (computer numerical controlled) milling machine out of foam with very low dielectric permittivity of 1.254. The numerical simulations and the experimental study are in good agreement with the theoretical model.

Effects of Electrical Stress in Solution-Processed Spin-On Glass Dielectric Films: Frequency Dependence

In this work, the effects of the frequency dependence of transparent dielectric based on Spin-on Glass (SOG) under electrical stress is presented. The SOG thin films were cured at 200 °C in ambient air. The capacitance-voltage and capacitance-frequency characteristics were measured in Metal-Oxide-Semiconductor (MOS) capacitors using the SOG thin film. In addition, electrical stress is applied to the MOS capacitors at different voltage values and during a long period of time. The results show, depending on the bias stress applied, a reversible interface charge contribution and an irreversible charge induced by interface states probably generated by the degradation of the film.