| 1. |
- Dyke, T.R., et al.
(författare)
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Experimental demonstration of data erasure for time-domain optical memories
- 1999
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Ingår i: Optical Society of America. Journal B: Optical Physics. - 0740-3224. ; 16:5, s. 805-811
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Tidskriftsartikel (refereegranskat)abstract
- Data erasure is considered an essential requirement for a practical optical time-domain memory, and it requires that the laser used have very good frequency stability. Such a laser is developed for this work, and data erasure is demonstrated with a sample of YSiO5:Eu3+ for write/rewrite pulse sequences of up to a duration of 100 μs. This is two orders of magnitude longer than had been achieved previously. Phase-sensitive detection is introduced and is shown to be invaluable for monitoring the write, rewrite, and read processes.
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| 2. |
- Elman, U., et al.
(författare)
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Influence of laser phase and frequency fluctuations on photon-echo data erasure
- 1996
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Ingår i: Optical Society of America. Journal B: Optical Physics. - 0740-3224. ; 13:9, s. 1905-1915
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Tidskriftsartikel (refereegranskat)abstract
- Erasure of data stored by use of photon echoes has been investigated as a function of data writing time and data storage time. The results clarify the requirements on laser phase and frequency stability for performing photon-echo data erasure. The analysis of phase and frequency stability of a light source by the photon-echo erasure process is illustrated. A theoretical analysis emphasizing the physical processes that affect the erasure efficiency as well as an extensive discussion of possible error sources are given. Finally, an approach to bit-selective photon-echo data erasure that is insensitive to laser phase and frequency fluctuations is suggested.
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| 3. |
- Elman, U., et al.
(författare)
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Statistical modeling and theoretical analysis of the influence of laser phase fluctuations on photon echo data erasure and stimulated photon echoes
- 1996
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Ingår i: Laser Physics. - 1054-660X. ; 6:4, s. 721-728
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Tidskriftsartikel (refereegranskat)abstract
- The effect of random laser phase fluctuations on stimulated photon echoes (SPEs) and on coherently added SPEs was studied and evaluated both experimentally and analytically with statistical methods. The general concept of describing laser frequency fluctuations as a stationary stochastic process is presented and applied to three specific SPE configurations. The effect of phase fluctuations on erasing an SPE by coherently adding another SPE, phase-shifted by 180 degrees relative to the first, is presented.
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| 4. |
- Kröll, Stefan, et al.
(författare)
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Photon-echo-based logical processing
- 1993
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Ingår i: Optics Letters. - 0146-9592. ; 18:21, s. 1834-1836
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Tidskriftsartikel (refereegranskat)abstract
- Word-by-word logical AND and OR operation with photon-echo processing is demonstrated for what is to our knowledge the first time. The photon-echo process can store sequences of optical data before processing. The present logical operations on 8- and 4-bit words are performed by using single-shot frequency-chirped photon echoes. Data rates of approximately 1 MHz, input energies of 1-10 nJ/bit, and output energies in the picojoule-per-bit range are demonstrated by using a transition with a transition probability of only 20 s(-1).
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| 5. |
- Luo, B., et al.
(författare)
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Amplification of photon echo signals by use of a fiber amplifier
- 1998
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Ingår i: Optics Letters. - 0146-9592. ; 23:6, s. 442-444
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of photon-echo processes typically lies in the 0.1–1% range. For many photon-echo-based applications suggested in optical storage and all-optical communication the photon-echo output pulses would need to be used as input data to a new photon-echo process. In such cases amplification of the photon-echo output signals would be necessary for an acceptable signal-to-noise ratio to be obtained. We show that a Pr-doped ZBLAN fiber is able to produce significant amplification of photon-echo signals generated in Pr-doped Y2SiO5 at 606 nm.
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| 6. |
- Mohan, R. K, et al.
(författare)
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Bit selective erasure of photon-echo data using Ti : S and dye laser systems: a comparative analysis
- 1998
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Ingår i: Optics Communications. - 0030-4018. ; 158:1-6, s. 149-158
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Tidskriftsartikel (refereegranskat)abstract
- It is investigated how the erasure efficiency for a single bit of data, stored using photon echoes, depends on the data writing time and data storage time. A comparative analysis of the erasure efficiency using a Ti:S laser system and a ring dye laser system is performed. The results clearly establish that the Ti:S laser system, which has a narrower line width than the dye laser system, could be used for efficient erasure over a much larger range of data writing and data storage times. A simple threshold detection-based scheme to convert the photon-echo signals into bits is also used to compare the performances of the two laser systems. A surprising but encouraging result was that it may not be absolutely necessary to have a very high erasure efficiency in an operable photon-echo storage system. (C) 1998 Elsevier Science B.V. All rights reserved.
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| 7. |
- Mohan, R. K., et al.
(författare)
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Regeneration of photon echoes with amplified photon echoes
- 1999
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Ingår i: Optics Letters. - 0146-9592. ; 24:1, s. 37-39
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Tidskriftsartikel (refereegranskat)abstract
- Photon-echo-based devices have been proposed for many applications in data storage, image processing, and optical communications. Many of these applications would benefit if the output from the photon-echo process could be used as input in a second photon-echo process. We demonstrate the generation of such secondary echoes, using the amplified output from an initial photon-echo process. The amplification is performed with a Pr:ZBLAN fiber amplifier, which gives a gain of more than 300 at 606 nm when pumped with 320 mW of power at 476 nm.
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| 8. |
- Smartt, S. J., et al.
(författare)
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PESSTO : survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 579
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Tidskriftsartikel (refereegranskat)abstract
- Context. The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. PESSTO classifies transients from publicly available sources and wide-field surveys, and selects science targets for detailed spectroscopic and photometric follow-up. PESSTO runs for nine months of the year, January - April and August - December inclusive, and typically has allocations of 10 nights per month. Aims. We describe the data reduction strategy and data products that are publicly available through the ESO archive as the Spectroscopic Survey data release 1 (SSDR1). Methods. PESSTO uses the New Technology Telescope with the instruments EFOSC2 and SOFI to provide optical and NIR spectroscopy and imaging. We target supernovae and optical transients brighter than 20.5(m) for classification. Science targets are selected for follow-up based on the PESSTO science goal of extending knowledge of the extremes of the supernova population. We use standard EFOSC2 set-ups providing spectra with resolutions of 13-18 angstrom between 3345-9995 angstrom. A subset of the brighter science targets are selected for SOFI spectroscopy with the blue and red grisms (0.935-2.53 mu m and resolutions 23-33 angstrom) and imaging with broadband JHK(s) filters. Results. This first data release (SSDR1) contains flux calibrated spectra from the first year (April 2012-2013). A total of 221 confirmed supernovae were classified, and we released calibrated optical spectra and classifications publicly within 24 h of the data being taken (via WISeREP). The data in SSDR1 replace those released spectra. They have more reliable and quantifiable flux calibrations, correction for telluric absorption, and are made available in standard ESO Phase 3 formats. We estimate the absolute accuracy of the flux calibrations for EFOSC2 across the whole survey in SSDR1 to be typically similar to 15%, although a number of spectra will have less reliable absolute flux calibration because of weather and slit losses. Acquisition images for each spectrum are available which, in principle, can allow the user to refine the absolute flux calibration. The standard NIR reduction process does not produce high accuracy absolute spectrophotometry but synthetic photometry with accompanying JHK(s) imaging can improve this. Whenever possible, reduced SOFI images are provided to allow this. Conclusions. Future data releases will focus on improving the automated flux calibration of the data products. The rapid turnaround between discovery and classification and access to reliable pipeline processed data products has allowed early science papers in the first few months of the survey.
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