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Optics Letters

Multiple-bit long-term data storage by backward-stimulated echo in Eu^3+:YAlO_3

M. K. Kim, Ravinder Kachru

Published May 1, 1989• 59 citations
Publisher

Abstract

We have observed faithful storage and retrieval of multiple data pulses for up to 5 h in Eu(3+):YAlO(3) crystal by using the backward-stimulated echo. We find no loss of echo fidelity as the storage time is increased. Furthermore the lack of cross talk between the input data pulses suggests that faithful long-term storage and retrieval of a large number of data pulses are possible. Our measured echo-storage lifetime of 3.8 h is to our knowledge the longest reported thus far.

DOI
10.1364/ol.14.000423

Related papers

Multiple-Bit Long-Term Data Storage by Backward Stimulated Echo in eu3+:yalo3

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The backward stimulated echo has been considered as a novel high-speed high-density optical data storage method. But its potential application has been confined to transient dynamic memory because of relatively short lifetime of optical coherence inside low-temperature solids. Here we report the longest observed storage time of at least six hours in the 581.8 nm7F0-5D0 transition of eu 3+ -doped YAlO3 crystal at 2°K. The experiments are performed using YAG-pumped pulsed dye lasers, beamsplitters and optical delay lines to produce five DATA pulses, at 20 nsec intervals, and WRITE and READ pulses. The measured echo intensity as a function of storage time has exponential decay time of 3.8 hours. This very long storage time is due to the very small effective nuclear magnetic moments of Eu3+ ions, and is consistent with the long lifetime of spectral hole in this system. We also observed that the signal fidelity is not noticeably affected by the number of DATA pulses and the long storage time.

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Long-term image storage and phase conjugation by a backward-stimulated echo in Pr^3+:LaF_3

M. K. Kim, Ravinder Kachru

We have observed spatial-image storage and phase conjugation, using a backward-stimulated echo in a solid sample. The image storage and the delayed phase conjugation were observed to last for at least 15 sec, which is 3 × 105 times longer than the radiative lifetime of the excited state. The backward-stimulated echo produced on the 3H4–3P0 transition of Pr3+:LaF3 is found to be a phase-conjugated spatial reproduction of the first excitation pulse. The image storage time depends strongly on the sample temperature.

Journal of the Optical Society of America B•Mar 1, 1987•28 citations
We have observed faithful storage and retrieval of multiple data pulses for up to 5 h in Eu(3+):YAlO(3) crystal by using the backward-stimulated echo. We find no loss of echo fidelity as the storage time is increased. Furthermore the lack of cross talk between the input data pulses suggests that faithful long-term storage and retrieval of a large number of data pulses are possible. Our measured echo-storage lifetime of 3.8 h is to our knowledge the longest reported thus far.
The backward stimulated echo has been considered as a novel high-speed high-density optical data storage method. But its potential application has been confined to transient dynamic memory because of relatively short lifetime of optical coherence inside low-temperature solids. Here we report the longest observed storage time of at least six hours in the 581.8 nm7F0-5D0 transition of eu 3+ -doped YAlO3 crystal at 2°K. The experiments are performed using YAG-pumped pulsed dye lasers, beamsplitters and optical delay lines to produce five DATA pulses, at 20 nsec intervals, and WRITE and READ pulses. The measured echo intensity as a function of storage time has exponential decay time of 3.8 hours. This very long storage time is due to the very small effective nuclear magnetic moments of Eu3+ ions, and is consistent with the long lifetime of spectral hole in this system. We also observed that the signal fidelity is not noticeably affected by the number of DATA pulses and the long storage time.
The successful storage and retrieval of 248-bit temporal optical data in Eu(3+):YAlO(3) by accumulated photon echoes is reported. Owing to the long storage time of this crystal, the input data can be written bit by bit by quickly varying the separation of two laser pulses, while the stored data are recalled simultaneously after some storage period, which extends up to a few hours. The maximum data length, previously thought to be limited by the optical dephasing time T(2), has been found to be four times shorter than T(2) and attributable to spectral diffusion.
Using a frequency-chirped ring dye laser, we have stored and recalled as much as 48 bits of information with the copropagating stimulated-echo geometry on the (3)H(4)-(1)D(2) transition in Pr(3+):YAlO(3). Since the copropagating excitation scheme has all the excitation pulses spatially overlapping, this technique will be useful to the practical implementation of stimulated-echo memory because there is no need for alignment of beams. Our experiments also demonstrate that frequency chirping of the excitation pulses dramatically improves not only pulse-shape reproduction by the echo pulse but also the shot-to-shot stability of the amplitude of the recalled data.
We have observed spatial-image storage and phase conjugation, using a backward-stimulated echo in a solid sample. The image storage and the delayed phase conjugation were observed to last for at least 15 sec, which is 3 × 105 times longer than the radiative lifetime of the excited state. The backward-stimulated echo produced on the 3H4–3P0 transition of Pr3+:LaF3 is found to be a phase-conjugated spatial reproduction of the first excitation pulse. The image storage time depends strongly on the sample temperature.