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Er'el Granot

Bio: Er'el Granot is an academic researcher from Ariel University. The author has contributed to research in topics: Dispersion (optics) & Brillouin scattering. The author has an hindex of 15, co-authored 132 publications receiving 801 citations. Previous affiliations of Er'el Granot include Israel Atomic Energy Commission & Tel Aviv University.


Papers
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Journal ArticleDOI
TL;DR: In this article, the role of quantum statistics in the decay dynamics of a multi-particle state, which is suddenly released from a confining potential, is investigated, and the exact dynamics is presented for both bosons and fermions.

15 citations

Journal ArticleDOI
TL;DR: Results are reported for a 2D nonlinearizable model whose P-symmetric symmetry remains unbroken for arbitrarily large values of the gain-loss coefficient and an extended 2D model with the imaginary part of potential ~xy in the Cartesian coordinates.
Abstract: The real spectrum of bound states produced by $${\bf{P}}{\bf{T}}$$ -symmetric Hamiltonians usually suffers breakup at a critical value of the strength of gain-loss terms, i.e., imaginary part of the complex potential. The breakup essentially impedes the use of $${\bf{P}}{\bf{T}}$$ -symmetric systems for various applications. On the other hand, it is known that the $${\bf{P}}{\bf{T}}$$ symmetry can be made unbreakable in a one-dimensional (1D) model with self-defocusing nonlinearity whose strength grows fast enough from the center to periphery. The model is nonlinearizable, i.e., it does not have a linear spectrum, while the (unbreakable) $${\bf{P}}{\bf{T}}$$ symmetry in it is defined by spectra of continuous families of nonlinear self-trapped states (solitons). Here we report results for a 2D nonlinearizable model whose $${\bf{P}}{\bf{T}}$$ symmetry remains unbroken for arbitrarily large values of the gain-loss coefficient. Further, we introduce an extended 2D model with the imaginary part of potential ~xy in the Cartesian coordinates. The latter model is not a $${\bf{P}}{\bf{T}}$$ -symmetric one, but it also supports continuous families of self-trapped states, thus suggesting an extension of the concept of the $${\bf{P}}{\bf{T}}$$ symmetry. For both models, universal analytical forms are found for nonlinearizable tails of the 2D modes, and full exact solutions are produced for particular solitons, including ones with the unbreakable $${\bf{P}}{\bf{T}}$$ symmetry, while generic soliton families are found in a numerical form. The $${\bf{P}}{\bf{T}}$$ -symmetric system gives rise to generic families of stable single- and double-peak 2D solitons (including higher-order radial states of the single-peak solitons), as well as families of stable vortex solitons with m = 1, 2, and 3. In the model with imaginary potential ~xy, families of single- and multi-peak solitons and vortices are stable if the imaginary potential is subject to spatial confinement. In an elliptically deformed version of the latter model, an exact solution is found for vortex solitons with m = 1.

15 citations

Patent
14 Nov 2008
TL;DR: In this article, the authors proposed a method to determine the DGD of the optical line by measuring a relative change in spectral intensity near a clock frequency while varying the optical signal between a first state of polarization and a second state of polarisation.
Abstract: In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal to create a delayed electrical signal that compensates for a DGD of the optical line, and combining the delayed electrical signal with the first electrical signal to produce a fixed output electrical signal

14 citations

Journal ArticleDOI
TL;DR: It is shown both theoretically and experimentally that, unlike phase modulation, amplitude modulation increases the Brillouin amplifier gain and that this effect has a very narrow bandwidth.
Abstract: We investigate the spectral response of a Brillouin amplifier in the frequency regime within the stimulated-Brillouin-scattering (SBS) bandwidth. This is done by amplitude modulating the pump with a low frequency; therefore, unlike in previous studies, the spectrum of the modulated pump is, in all cases, smaller than the SBS bandwidth. We show both theoretically and experimentally that, unlike phase modulation, amplitude modulation increases the Brillouin amplifier gain and that this effect has a very narrow bandwidth. Only modulation frequencies that are lower than a certain cutoff frequency increase the gain. This cutoff frequency can be arbitrarily small.

14 citations

Journal ArticleDOI
TL;DR: In this article, the spectral response of a Brillouin amplifier in the frequency regime within the SBS bandwidth was investigated, and it was shown that amplitude modulation increases the amplifier gain.
Abstract: We investigate the spectral response of a Brillouin amplifier in the frequency regime within the SBS bandwidth. This is done by amplitude modulating the pump with a low frequency, and therefore, unlike previous studies, the spectrum of the modulated pump is, in all cases, smaller than the SBS bandwidth. We show both theoretically and experimentally that unlike phase modulation, which was reported in the literature, the amplitude modulation increases the Brillouin amplifier gain, and that this effect has a very narrow bandwidth. Only modulation frequencies that are lower than a certain cut-off frequency increase the gain. This cut-off frequency is inversely proportional to the fiber's length, and can therefore be arbitrarily small.

14 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors review recent progress in inducing and harnessing stimulated Brillouin scattering (SBS) in integrated photonic circuits, with special attention paid to photonic integration of applications such as narrow-linewidth lasers, slow-and fast-light, microwave signal processing, and non-reciprocal devices.
Abstract: We review recent progress in inducing and harnessing stimulated Brillouin scattering (SBS) in integrated photonic circuits. Exciting SBS in a chip-scale device is challenging due to the stringent requirements on materials and device geometry. We discuss these requirements, which include material parameters, such as optical refractive index and acoustic velocity, and device properties, such as acousto-optic confinement. Recent work on SBS in nano-photonic waveguides and micro-resonators is presented, with special attention paid to photonic integration of applications such as narrow-linewidth lasers, slow- and fast-light, microwave signal processing, Brillouin dynamic gratings, and nonreciprocal devices.

291 citations

Journal ArticleDOI
TL;DR: Two types of ultrasound-mediated biophotonic imaging are reviewed–acousto-optical tomography and photo-acoustic tomography–both of which are based on non-ionizing optical and ultrasonic waves.
Abstract: This article reviews two types of ultrasound-mediated biophotonic imaging–acousto-optical tomography (AOT, also called ultrasound-modulated optical tomography) and photo-acoustic tomography (PAT, also called opto-acoustic or thermo-acoustic tomography)–both of which are based on non-ionizing optical and ultrasonic waves. The goal of these technologies is to combine the contrast advantage of the optical properties and the resolution advantage of ultrasound. In these two technologies, the imaging contrast is based primarily on the optical properties of biological tissues, and the imaging resolution is based primarily on the ultrasonic waves that either are provided externally or produced internally, within the biological tissues. In fact, ultrasonic mediation overcomes both the resolution disadvantage of pure optical imaging in thick tissues and the contrast and speckle disadvantages of pure ultrasonic imaging. In our discussion of AOT, the relationship between modulation depth and acoustic amplitude is clarified. Potential clinical applications of ultrasound-mediated biophotonic imaging include early cancer detection, functional imaging, and molecular imaging.

249 citations

Proceedings Article
04 May 2008
TL;DR: It is shown that new types of nonlinear self-trapped modes can exist in optical PT synthetic lattices.
Abstract: We investigate the effect of nonlinearity in novel parity-time (PT) symmetric potentials. We show that new types of nonlinear self-trapped modes can exist in optical PT synthetic lattices.

203 citations

Journal ArticleDOI
Jean Toulouse1
TL;DR: In this paper, a review of optical nonlinearities in optical fibers is presented, pointing out the essential material and fiber parameters that determine them, emphasizing their variations for different values of essential parameters.
Abstract: Optical nonlinearities give rise to many ubiquitous effects in optical fibers. These effects are interesting in themselves and can be detrimental in optical communications, but they also have many useful applications, especially for the implementation of all-optical functionalities in optical networks. In the present paper, we briefly review the different kinds of optical nonlinearities encountered in fibers, pointing out the essential material and fiber parameters that determine them. We describe the effects produced by each kind of nonlinearity, emphasizing their variations for different values of essential parameters. Throughout the paper, we refer to recent systems applications in which these effects have been dealt with or exploited.

148 citations