Optical echo-spectroscopy of highly doped Tm:YAG

Two-pulse, stimulated and accumulated photon echoes are investigated for the first time in a highly doped crystal Tm: YAG containing 10 at.% Tm3+. The decay curves of the two-pulse and stimulated photon echoes generated at 793.15 nm on the transition 3H6 (1)-3H4 (1) of the impurity ions are measured in the absence of an applied magnetic field and parameters describing the energy and phase relaxation are determined. The dependence of the intensity of the accumulated photon echo on the number of excitation pulse pairs is investigated. © 2008 by Astro Ltd

Locking of a long-lived photon echo in a nonuniform electric field

A method is developed to control the generation of optical coherent responses in a resonance medium under the action of an external spatially nonuniform electric field. It is shown that a change in the field gradient between the data recording and reading by means of a photon echo suppresses the response generation after the action of the reading pulse, resulting in locking of the data recorded in the medium. The possibilities of using this method in optical memory devices based on a photon echo are discussed

Investigation of femtosecond photon echo in dye-doped polymer film at room temperature

Signals of primary and stimulated femtosecond photon echo were found and investigated at room temperature in a polyvinyl butyral film doped with phthalocyanine molecules. The decay curve of relative intensity and the spectrum of the signal of primary femtosecond photon echo were recorded. The physical mechanism of formation of such signals in a system of impurity centers excited through the phonon wing of the optical absorption band was discussed. © 2007 by Allerton Press, Inc

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

Angular regularities of the photon echo in doped crystals

The regularities of the two-pulse photon echo generation in doped crystals under changes in the angle a between directions of propagation of pumping pulses are investigated theoretically. The explanation of some experimental results obtained by U.P. Wild and coworkers, in particular, the modulation character of the response-intensity dependence on the angle a is presented. Copyright © 1996 by MANK Hayka/Interperiodica Publishing

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

Formation of photonic echo signals in the presents of a strong concentration quenching effect

The connection between the photonic echo formation in crystals doped by rare-earth elements and the concentration effects was studied. The application of optical echo spectroscopy in studies of garnet crystals with a high content of thulium impurity was demonstrated. By the example of activated crystals of ruby and lanthanum trifluoride, the spectral transformation of the photonic echo signals was analyzed in the present of the concentration quenching effect. © 2009 Allerton Press, Inc

Spatial and spectral properties of a photon echo

Spatial and spectral regularities in the formation of photon echo signals are studied. The frequency shift of the signal of a primary photon echo with respect to the carrier frequency of excitation laser pulses that was experimentally observed upon variation of the angle between the wave vectors of the laser pulses is explained. The feasibility of high-resolution angular optical echo spectroscopy is shown

A new technique for laser cooling with superradiance

We present a new theoretical scheme for laser cooling of rare earth doped solids with optical super-radiance (SR), which is the coherent, sharply directed spontaneous emission of photons by a system of laser excited rare earth ions in the solid state host (glass or crystal). We consider an Yb3+ doped ZBLAN sample pumped at the wavelength 1015 nm with a rectangular pulsed source with a power of ~433W and duration of 10ns. The intensity of the SR is proportional to the square of the number of excited ions. This unique feature of SR permits a dramatic increase in the rate of the cooling process in comparison with the traditional laser cooling of the rare earth doped solids with anti-Stokes spontaneous incoherent radiation (fluorescence). This scheme overcomes the limitation of using only low phonon energy hosts for laser cooling.Comment: 10 pages,6 figure

Angular regularities of the photon echo in doped crystals

The regularities of the two-pulse photon echo generation in doped crystals under changes in the angle a between directions of propagation of pumping pulses are investigated theoretically. The explanation of some experimental results obtained by U.P. Wild and coworkers, in particular, the modulation character of the response-intensity dependence on the angle a is presented. Copyright © 1996 by MANK Hayka/Interperiodica Publishing