D. V. Sidorov

Reflection of wave beams, pulses, and packets from apodized and chirped Bragg layered structures

The time delay, space shift and widening of wave packet transmitted and reflected by structures with Bragg mirrors have been investigated. The specific structures such as Bragg mirrors, resonators, and structures with chirp variation of thickness of the “period” have been considered. The calculation has been carried out under the conditions that carrier frequency and incidence angle is in the vicinity of the Bragg resonance. Integral (mass center) and differential (group) estimates of the delay time and space shift have been compared. The conditions for the appearance of anomalous (negative) mass center delay or mass center shift (Goos-Hänchen shift) of the reflected wave packet have been determined. The shape transformations of the wave packet illuminating periodic and quasiperiodic apodized Bragg reflectors have been under consideration. Spatial apodization of permittivity contrast yields much smaller shape deformation of the transmitted wave packet upon incidence at angles and carrier frequency near the edges of reflection band, as well in Bragg reflection band, in comparison with phenomena in similar periodic structures. The values of group delay for layered structures with a small chirp variation of optical (electrical) thickness of the period along longitudinal coordinates have been experimentally obtained in microwave range.

Bragg structures with thin lossy layers

The behavior of quasi-periodic and aperiodic (chirp) Bragg structures with thin lossy layers was examined. In order to determine the frequency dependence of the reflection coefficient transmission matrix method was used. A deep minimum of the reflection coefficient for any frequency is implemented by proper choice of the thickness of the last thin film and its optical distance to the substrate. The possibility of providing broadband reflection by aperiodic structures has been offered.

Multiple reflections from non-periodic Bragg layered structures

The parameters of pulses reflected from non-periodic Bragg layered structures have been investigated. The specific structures such as asymmetric resonators with periodic Bragg reflectors and structures with chirp variation of the thickness of the “period” have been examined. The numerical investigations have been made both in Bragg band and outside it. The frequency characteristics of the structures have been interpolated by the methods of Prony and continued fractions.

Delays of multiple reflections from Bragg layered structures

The time delays of pulses reflected from periodic and non-periodic Bragg layered structures have been investigated. The specific structures such as Bragg reflectors and structures with chirp variation of thickness of the “period” have been considered. The calculation has been carried out under the conditions that carrier frequency is in the vicinity of the Bragg resonance values. The parameters of interpolating models have been found by methods Prony and continued fractions.

Eigen parameters of Bragg layered structures

The influence of various types of distortion of periodicity on the eigen parameters of the layered Bragg resonators has been analyzed. The conditions of reduction of the quality factor of unwanted side Bragg oscillations in quasiperiodic apodized resonators have been determined. It has been proposed the construction of periodic and quasiperiodic structures and apodized Bragg resonators with thin contrast layers, which are relatively easy technologically implemented in the microwave range. “Unsuccessful” positions of active layers and lumped elements are observed. The measurements results of reflection coefficient of periodic and quasiperiodic apodized structures and resonators with thin contrast layers are presented.

Eigen parameters of quasiperiodic Bragg layered structures

The influence of various types of apodization on the eigen parameters of the distributed Bragg reflector, layered Bragg reflectors and resonators has been analyzed. The conditions of reduction of the quality factor of unwanted side Bragg oscillations in quasiperiodic apodized resonators have been determined. It has been proposed the construction of periodic and quasiperiodic structures and apodized Bragg resonators with thin contrast layers, which are relatively easy technologically implemented in the microwave range. The measurements results for periodic and quasiperiodic apodized structures and resonators with thin contrast layers are presented.

Reflection of wave beams and pulses from non- periodic bragg layered structures

The time delay, space shift and widening of wave packet transmitted and reflected by structures with Bragg mirrors have been investigated. The specific structures such as Bragg mirrors, resonators, and structures with chirp variation of thickness of the “period” have been considered. The calculation has been carried out under the conditions that carrier frequency and incidence angle is in the vicinity of the Bragg resonance. Integral (mass center) and differential (group) estimates of the delay time and space shift have been compared. The conditions for the appearance of anomalous (negative) mass center delay or mass center shift (Goos-Hänchen shift) of the reflected wave packet have been determined. The shape transformations of the wave packet illuminating periodic and quasiperiodic apodized Bragg reflectors have been under consideration. Spatial apodization of permittivity contrast yields much smaller shape deformation of the transmitted wave packet upon incidence at angles and carrier frequency near the edges of reflection band, as well in Bragg reflection band, in comparison with phenomena in similar periodic structures. The values of group delay for layered structures with a small chirp variation of optical (electrical) thickness of the period along longitudinal coordinates have been experimentally obtained in microwave range.

Bragg resonance in multilayer structure with compound nonlinear layer

Transmission of plane monochromatic waves through the Bragg layered resonators have been considered. Iterative numeric solutions for complex amplitudes of reflected and transmitted waves are found by modified method of transmission matrices. Influences of Kerr nonlinearity of permittivity of some layers on resonance properties have been investigated. Hysteresis behavior is observed for case of combination of high quality factor and nonlinearity.

Pulse shape transformation upon reflection from Bragg resonators with asymmetric feedback

The transformation of the shape of pulses reflected by Bragg resonators with step-up and step-down perturbation types of period contrast under conditions than carrier frequency is in the vicinity of the resonance Bragg frequency have been considered. Integral and differential estimates of the delay time have been compared. The coefficients of skewness and kurtosis for the reflected pulses versus carrier frequency have been calculated within Bragg reflection band. The conditions for the appearance of negative mass center delay of the reflected pulses have been determined. The conditions of the anomalous values of the delay time have been generalized for the case of asymmetric feedback in Bragg resonators.

Pulse shape transformation upon reflection and transmission in bragg structures

The transformation of the shape of pulse reflected and transmitted by Bragg mirrors, resonators, and structures with chirp variation of thickness of the “period” under conditions than carrier frequency is in the vicinity of the resonance Bragg frequency is considered. Integral and differential estimates of the delay time have been compared. The coefficients of skewness and kurtosis for the reflected and transmitted pulses with various duration versus carrier frequency if it was in Bragg reflections band were calculated. The conditions for the appearance of negative time delay of mass center of the reflected pulse have been determined. The values of group delay for layered structures with a small chirp variation of optical (electrical) thickness of the period along longitudinal coordinates have been obtained.