Photon echo locking via inhomogeneous broadening controlled by a weak pulsed magnetic field and optical storage

Two-pulse photon echo in LiLuF 4:Er 3+ crystal subjected to a weak pulsed magnetic field is investigated. The dependence of the echo intensity on the magnetic field switching time is analyzed. Prospects for using photon echo modulation by a weak magnetic field for photon-echo-based storage are discussed. © 2011 SPIE

New possibilities of photon echo: Determination of ground and excited states g-factors applying a weak magnetic field pulse

© Published under licence by IOP Publishing Ltd. We have measured the magnetic parameters of a paramagnetic ion in the ground and excited states by controlling the relative phases of excited dipoles with pulse of a weak magnetic field. Er3+ in two crystals LuLiF4 and YLiF4 has been used as a paramagnetic ion. The second matrix was used for control. Optical transition is 4I15/2 → 4F9/2

Low magnetic fields behavior of photon echo in LuLiF4:Er3+

It is reported about the first observation and studying of the photon echo in LuLiF4:Er3+. The energy transition is 4I15/2 → 4F9/ 2 (λ = 6536 Å). The density of ErF3 is 0.025 wt%. The operation temperature is 1.9 K. Measurements were spent at low (up to 1200 Oe) and even zero external magnetic fields. It was studied a behavior of the photon echo intensity versus the magnetic field mgnitude and direction about the crystal axis C and versus the laser pulse separation t12. It was observed an expotential growth and then, after some plateau, an exponential decreasing of the photon echo intensity as a function of magnetic field with increasing of the magnetic field from zero value. The parameters describing the exponential growth and decreasing are not depended on direction of magnetic field. Value of a magnetic field at which the echo intensity accepts the maximum, and quantity of this maximum decrease with increased the pulse sepatation t12 and the angle θ between the magnetic field and crystals axis. The echo intensity expotentially decreases with increased θ. The parameter describing the exponential decreasing is not depended on the magnitude of the field. The echo intensity as a function of pulse separation shows exponential decay. The phase relaxation time is depended on the magnitude and direction of the magnetic field. T2 is equal to 202±16 ns at zero magnetic field. Phenomenological formula is suggested, which qualitatively presents the mentioned dependencies. Polarization properties of the backward photon echo in this crystal are studied also. A graph is presented. Echo size versus magnetic field directed as along optic axis as at an angle of θ = 5° of different values of t12. The color symbols show experimental points. The solid curves were calculated using experession (1). The Y-scale is logarithmic. © 2006 by Astro Ltd. Published exclusively by Wiley-VCH Verlag GmbH & Co. KGaA

Incoherently generated photon echo in a crystal of ruby using fiber optical delay line

This paper is about the possibilities of optically dense impurity media spectroscopy by means of the incoherent photon echo. The theoretical model of the phenomenon is given. The results of experiment on incoherent photon echo in a crystal of ruby at liquid helium temperature are presented. Fiber optical delay line was used to make an incoherence of the excitation radiation. The dependence of the incoherent echo intensity on the excitation wavelength was studied. The echo decay curve was obtained and the phase relaxation time was found to be equal to 98 ns

Incoherent photon echo in spectroscopy of optically dense impurity media

The possibility of using incoherent photon echo in spectroscopy of optically dense impurity media is considered. A theoretical approach to description of this phenomenon is presented. The experimental data on incoherent photon echo in ruby at liquid-helium temperature, with transport of an excitation pulse through a fiber, are reported. The spectral dependence of the echo intensity is studied. The decay curve for an incoherent echo signal is investigated, and the phase relaxation time is found to be 98 ns. © Allerton Press, Inc. 2008

Weak magnetic field behavior of photon echo in a LuLiF4:Er 3+ crystal

We report the first observation and study of the photon echo in Er 3+:LuLiF4. The energy transition is 4 I 15/2 → 4 F 9/2 (λ = 6536 Å). The density of ErF3 is 0.025 wt %. The operation temperature is 1.9 K. Measurements were made at low (up to 1200 Oe) and even zero external magnetic fields. We studied the behavior of the photon echo intensity vs. the magnetic field magnitude and direction about the crystal axis C and vs. the laser pulse separation t 12 and observed an exponential growth and then, after a certain plateau, an exponential decrease in the photon echo intensity as a function of magnetic field upon increasing the magnetic field from zero. The parameters describing the exponential growth and decrease are independent of the direction of magnetic field. The value of the magnetic field (∼20-200 Oe) at which the echo intensity is maximal and the value of the maximum itself decrease with increasing pulse separation t 12 and the angle Θ between the magnetic field and crystal axis. The echo intensity decreases exponentially with increasing Θ. The parameter describing the exponential decrease is independent of the magnitude of the field. The echo intensity as a function of pulse separation shows exponential decay. The phase relaxation time depends on the magnitude and direction of the magnetic field. T 2 is equal to 202 ± 16 ns at zero magnetic field. A phenomenological formula is suggested, which qualitatively presents the mentioned dependences, and the polarization properties of the backward photon echo in this crystal are studied. Because the ion of trivalent erbium is an optimum data carrier, the above results show that fine control of the multichannel transfer of processed optical information may be achieved by weak magnetic fields. © Nauka/Interperiodica 2007

Multichannel information processing in the optical echo-processors on the basis of Van-Fleck paramagnet crystals

The analysis of various modes of multichannel information recording and readout in conditions of a stimulated (accumulated and long-living) photon echo in the crystals doped with rare earth ions which are known as Van-Fleck paramagnets has been performed in order to utilize them in the operation of low-temperature optical echo-processors. © Allerton Press, Inc., 2012

СПОСОБ ДИАГНОСТИКИ ОСТРЫХ КИШЕЧНЫХ ИНФЕКЦИЙ У НОВОРОЖДЕННЫХ ДЕТЕЙ

In this article development of mathematical model of diagnosis of sharp intestinal infections in newborn children depending on the nature of the infectious agent is described. All risk factors promoting development of intestinal infections were considered. By means of a method of logical regression the medico-mathematical model the express of diagnosis of sharp intestinal infections in newborn children was developed.Разработана математическая модель диагностики острых кишечных инфекций у новорожденных детей в зависимости от природы инфекционного агента. Были рассмотрены все факторы риска, способствующие развитию кишечных инфекций. С помощью метода логической регрессии была разработана медико-математическая модель экспресс диагностики острых кишечных инфекций у новорожденных детей, что значительно сокращает сроки постановки верного диагноза и начала лечения.