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.

Mutually-modulated cross-gain modulation and slow light

Abstract: The interaction of pump and Stokes light in a Brillouin medium, where both beams are modulated, can be utilized for controlling the group velocity of the amplified Stokes (or depleted pump). The dependence of the group velocity for this mutually-modulated cross-gain modulation (MMXGM) technique on the Brillouin gain parameter is studied. A sharp transition to slow light occurs in the G1α/β≈1 regime, where G1 is the Brillouin gain parameter, and α and β are the pump and Stokes modulation indices, respectively. A comparison of MMXGM slow light to the Brillouin dispersion-based slow-light technique reveals the fundamental differences between them. The formation of higher harmonics of the modulation frequency is also discussed. The theoretical predictions are experimentally corroborated and potential applications in fiber-based sensing and interferometry are discussed.

Eavesdropping and Network Analyzing Using Network Dispersion

Abstract: The dispersion effect in an optical network is utilized in several applications. The pattern of the received signal is matched to a pre-prepared data bank. Useful data can be retrieved from this by data matching. It is demonstrated that in a Time-Division-Multiplexing configuration, not only that the data can be retrieved but also the data of the adjacent detectors, i.e., this method can be utilized for optical eavesdropping. Moreover, it is also shown that this method can be utilized as an affordable method to synchronize the data stream and to find the length of the dispersive fiber (or, for a given fiber length, this method can be used to measure the fiber's dispersion coefficient). One of the benefits of this method is that it can operate, while the network is running without deteriorating its performances. The conclusions are based on theoretical and numerical analysis as well as on experimental results.

Kilohertz laser frequency sensing with Brillouin mutually modulated cross-gain modulation

Abstract: Using mutually modulated cross-gain modulation, Stokes optical frequency changes are converted into modulation phase changes with high sensitivity. In the slow-light transition regime, we demonstrate kilohertz sensitivity to the Stokes optical carrier frequency. The sensitivity is inversely proportional to the modulation frequency of the pump and Stokes beams.

Short time propagation of a singular wave function: Some surprising results

Abstract: The Schrodinger evolution of an initially singular wave function was investigated. First it was shown that a wide range of physical problems can be described by initially singular wave function. Then it was demonstrated that outside the support of the initial wave function the time evolution is governed to leading order by the values of the wave function and its derivatives at the singular points. Short-time universality appears where it depends only on a single parameter—the value at the singular point (not even on its derivatives). It was also demonstrated that the short-time evolution in the presence of an absorptive potential is different than in the presence of a nonabsorptive one. Therefore, this dynamics can be harnessed to the determination whether a potential is absorptive or not simply by measuring only the transmitted particles density.

Analytical solution for a lossy singly resonant optical parametric oscillator

Abstract: We present a simple analytical solution for a singly resonant optical parametric oscillator (OPO). The analysis permits calculating the depletion efficiency of the OPO even when the resonated signal (or idler) suffers from strong intracavity losses. The main results are (1) that the maximum efficiency as a function of the pump power is highly dependent on the mirror reflectivity and on the intracavity losses; (2) that the threshold intensity and the pump intensity at which maximum efficiency is reached depend on the reflectivity, and the ratio between the two intensities maintains the relation 1⩽I3max/Ith⩽π2/4; and (3) that the maximum efficiency for a Gaussian beam is 70%.

Inducing and harnessing stimulated Brillouin scattering in photonic integrated circuits

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.

Ultrasound-mediated biophotonic imaging: A review of acousto-optical tomography and photo-acoustic tomography

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.

Optical solitons in PT periodic potentials

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.

Optical nonlinearities in fibers: review, recent examples, and systems applications

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.