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Signal beam

About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.


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Journal ArticleDOI
TL;DR: In this paper, the angular selectivity of a hologram and crosstalk for segmented data pages were investigated using numerical simulation and the experimental results showed a practical bit-error rate on the order of 10-3.
Abstract: To improve the recording density of angle-multiplexed holographic memory, it is effective to increase the numerical aperture of the lens and to shorten the wavelength of the laser source as well as to increase the multiplexing number. The angular selectivity of a hologram, which determines the multiplexing number, is dependent on the incident angle of not only the reference beam but also the signal beam to the holographic recording medium. The actual signal beam, which is a convergent or divergent beam, is regarded as the sum of plane waves that have different propagation directions, angular selectivities, and optimal angular spacings. In this paper, focusing on the differences in the optimal angular spacing, we proposed a method to control the angular spacing for each segmented data page. We investigated the angular selectivity of a hologram and crosstalk for segmented data pages using numerical simulation. The experimental results showed a practical bit-error rate on the order of 10-3.

6 citations

Proceedings ArticleDOI
M. A. Duguay1, J.W. Hansen
01 Jan 1968
TL;DR: In this article, the authors describe a technique for the display of sub-nanosecond light pulses, which is the optical analog of the technique used in electronic sampling oscilloscopes.
Abstract: In this paper we shall describe a technique for the display of subnanosecond light pulses which is the optical analog of the technique used in electronic sampling oscilloscopes. The optical pulse waveform to be displayed is assumed to repeat itself with period T. A mode-locked laser provides a source of sampling pulses of a few picoseconds duration. The period of this laser is adjusted to be T + δT, where δT s is proportional to ∫ I 1 I 2 dt, where I 1 and I 2 are the intensities of the light signal beam and sampling beam, respectively. If the signal beam is slowly varying compared to the very brief sampling pulse, we have: Y s = constant × I 1 (t n ) where t n is the arrival time of the nth sampling pulse at the nonlinear crystal. Because of the slightly unequal periods, the sampling pulse scans the light signal in steps of δT seconds. Displays of the sum frequency signal Y s on a conventional oscilloscope therefore constitute a sampled display of the light signal. In an experiment to test the method, sampled displays of subnanosecond pulses generated by a mode-locked He-Ne laser (wavelength 0.633µ) were obtained. The source of sampling pulses, ∼4 psec in duration, was a mode-locked Nd:glass laser (wavelength 1.06µ). The two unfocussed beams were mixed in a KDP crystal and the sum frequency signal at 0.397µ was detected by a photomultiplier and displayed on an oscilloscope. The period T of the He-Ne laser pulses was 12.44 nanoseconds, and the sampling step δT was varied between 100 psec and 400 psec. Using this method the He-Ne laser pulse width was observed to vary between 700 psec and 900 psec depending on the He-Ne laser adjustment. These measurements were confirmed with a fast photodiode and an electronic sampling oscilloscope. The average He-Ne laser power was ∼1 mw. In the KDP crystal the sampling pulses converted red light into UV light with an efficiency of about 5%. Since with focussed beams an efficiency of better than 20% can be achieved, it appears possible to optically sample light signals with average powers much less than a milliwatt.

6 citations

Journal ArticleDOI
TL;DR: A simple detection scheme that uses an 8-bit CMOS camera and spans over 60-dB dynamic range and is experimentally validated in a scanning and a single-shot autocorrelator.
Abstract: We have developed a simple detection scheme that uses an 8-bit CMOS camera and spans over 60-dB dynamic range. By use of noise reduction techniques, the 8-bit CMOS camera yields a 40-dB dynamic-range signal, which is further increased by 20 dB by making a replica of the signal beam on another part of the detector chip. We have experimentally validated this scheme in a scanning and a single-shot autocorrelator.

6 citations

Proceedings ArticleDOI
12 Jun 2005
TL;DR: In this article, the experimental parametric amplification of optical vortex beams (OVB) in a degenerate type I optical parametric amplifier (OPA) was studied and it was shown that the amplification gain in the transverse plane depends on the pump beam profile and the relative phase between interacting beams.
Abstract: This work deals with the experimental parametric amplification of optical vortex beams (OVB) in a degenerate type I optical parametric amplifier (OPA). Results show that in a degenerate type I OPA, the amplification gain in the transverse plane depends on the pump beam profile as well as the relative phase between interacting beams. It leads to amplification or de-amplification that reshapes the signal beam in its transverse plane and preserves the orbital angular momentum when an optical vortex is carried by the signal beam. Then, new various patterns are obtained depending on phase matching condition, topological charge of the vortex and wave front of the pump beam.

6 citations

Journal ArticleDOI
TL;DR: In this article, the concept of dividing the crystal slab into layers together with the mathematics of the diagonalization matrix are developed to calculate the diffraction of the hologram, and the conditions for keeping the same fields of the reconstructed signal beam and the transmitted signal beam are discussed.
Abstract: In a volume phase hologram recorded by two-beam coupling in photorefractive crystal, the refractive index modulation and the phase shift are both path dependent. In this paper, the concept of dividing the crystal slab into layers together with the mathematics of the diagonalization matrix are developed to calculate the diffraction of the hologram. As a result, a general analytic solution is achieved. For the use of novelty filtering in image processing and interferometric measurement, the conditions for keeping the same fields of the reconstructed signal beam and the transmitted signal beam are discussed.

6 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202215
202131
202040
201929
201844