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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.


Papers
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Journal ArticleDOI
TL;DR: In this article, the coupled wave equations that describe polarization-sensitive parametric amplification based on four-wave mixing (FWM) in standard (randomly birefringent) optical fibers were developed from first principles.
Abstract: We develop from first principles the coupled wave equations that describe polarization-sensitive parametric amplification based on four-wave mixing (FWM) in standard (randomly birefringent) optical fibers. We show that in the small-signal case these equations can be solved analytically, and permit us to predict the gain experienced by the signal beam as well as its state of polarization (SOP) at the fiber output. We find that, independently of its initial value, the output SOP of a signal within the parametric gain bandwidth is solely determined by the pump SOP. We call this effect of pulling the polarization of the signal towards a reference SOP the polarization attraction, and we call the parametric amplifier the FWM polarizer (which can equivalently be called the fiber-optic parametric amplifier polarizer). Our theory is valid beyond the zero polarization mode dispersion (PMD) limit, and it takes into account moderate deviations of the PMD from zero. In particular, our theory is capable of analytically predicting the rate of degradation of the efficiency of the parametric amplifier, which is caused by the detrimental PMD effect.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of the coherence amplitudes on the ratio of the pump-field intensities when there is a large vibrational discrepancy between ground and excited electronic states and a general solution for the unitary time development during the probe pulse are investigated.
Abstract: The delayed or time-domain four-wave-mixing experiment is treated in the regime of intense near-resonant pulses. The interaction with the radiation during both pump and probe pulses is considered to all powers of the electric field amplitude. Analytical results are obtained for an effective four-level system. These include the dependence of the coherence amplitudes on the ratio of the pump-field intensities when there is a large vibrational discrepancy between ground and excited electronic states and a general solution for the unitary time development during the probe pulse. For the first time, delayed coherent anti-Stokes Raman scattering is detected from highly dilute (10-ppm) guest molecules. Illustrative examples are presented for the system of pentacene in benzoic acid at low temperature. Vibronic-free induction decay and the effect of field inhomogeneity across the beam profile are found to be essential for understanding the observed intensity and spectral distribution of the signal beam in the region of optimum pulse intensity.

23 citations

Patent
09 May 2002
TL;DR: In this paper, a system for saving holographic digital data compatible with a CD player and a DVD player is provided, which includes a light source generating a reference beam, a holographic optical element recording an interference pattern of the reference beam and a plurality of reproducing beams having the specific size, and a beam splitter splitting the reproducing beam into reflecting beams and projecting beams.
Abstract: PURPOSE: A system for saving holographic digital compatible with a CD player and a DVD player is provided to reduce the equipment cost by adding holographic optical elements. CONSTITUTION: A system for saving holographic digital data compatible with a CD player and a DVD player includes a light source(102) generating a reference beam; a holographic optical element(104) recording an interference pattern of the reference beam and a plurality of beams having the specific size, thereby generating a plurality of reproducing beams corresponding to the specific sized beams if the reference beam is irradiated; a beam splitter(106) splitting the reproducing beams into reflecting beams and projecting beams, and using one of reflecting beams and projecting beams as a holographic reference beam; a spatial light modulator(122) modulating one of reflecting beams and projecting beams to correspond to a holographic input signal, thereby generating a holographic signal beam; a media(110) storing an interference pattern of the holographic reference beam and the holographic signal beam, reflecting the holographic reference beam for generating a CD/DVD reflecting beam proceeding the opposite direction of the holographic reference beam; a signal sensing element displaying the holographic reproducing beam and sensing the CD/DVD reflecting beam in case that holographic reference beam is irradiated.

23 citations

Journal ArticleDOI
TL;DR: In this article, a numerical analysis of the temporal and spatial beam properties of nanosecond optical parametric oscillators (OPOs) was performed for a 355-nm-pumped critically phase-matched OPO of beta-barium borate.
Abstract: We report on a numerical analysis of the temporal and spatial beam properties of nanosecond optical parametric oscillators (OPOs). The analysis is performed for a 355-nm-pumped critically phase-matched OPO of beta-barium borate. The calculations provide detailed information on the dependence of the OPO beam quality (measured by the quality factor M2) on pump energy. An important result is the strong increase of the M2 value for pump energies exceeding 1–2 times the energy at threshold. Furthermore, a temporal analysis of single OPO pulses indicates that the M2 value strongly increases during the first few nanoseconds of the OPO oscillation. This increase is understood by considering the temporal dynamics of the spatial profiles of the OPO signal beam and the depleted pump radiation.

23 citations

Patent
15 Mar 1995
TL;DR: In this paper, an optical self-referencing ultrasonic receiver for detecting ultrasonic waves is proposed, which is capable of operating in a heterodyne mode and is self-aligning.
Abstract: An optical self-referencing ultrasonic receiver for detecting ultrasonic waves removes wavefront distortions imparted on the optical beams by diffusely reflecting readout surfaces or other sources, compensates for noise induced phase errors on the readout beam, compensates for amplitude noise present on the readout beam, substantially matches the wavefronts of the readout and reference beams, is capable of operating in a heterodyne mode and is self-aligning. In one embodiment, ultrasonic waves are measured by directing a signal beam and a reference beam to a surface of the workpiece so that the signal beam reflects off an area that is being vibrated by the ultrasonic waves, and the reference beam reflects off a different area of the surface. The signal beam gets phase modulated by the ultrasonic wave induced vibrations and also by other noise induced vibrations. The reference beam only gets phase modulated by the noise induced vibrations. The phase modulated signal and reference beams are directed to a wavefront compensator that overlaps the beams, substantially matches their wavefronts and removes wavefront distortions without altering their respective optical phases. The wavefront compensated beams are directed to a coherent detector whose output signal has a phase shift which corresponds to the difference between the optical phase shift on the signal beam (due to ultrasonic wave vibrations and noise vibrations) and the optical phase shift on the reference beam (due to noise vibrations only). Thus, noise induce vibrations common to both beams are canceled out.

23 citations


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