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Bessel beam
About: Bessel beam is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 42264 citations.
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TL;DR: The light output power of the LED is apparently increased by introducing the array patterns without influencing its current-voltage characteristics and the patterned LED as a transmitter is embedded in the visible light communication system for evaluating the transmission signal quality.
Abstract: A significant enhancement of light extraction of light-emitting diodes (LEDs) with micro patterns has been experimentally investigated. The micro patterns on the surface of a polymer layer are fabricated by a femtosecond laser Bessel beam for obtaining microhole arrays with large depth, resulting in the reduction of photon loss by total internal reflection (TIR) at the surface of the LED. The light output power of the LED is apparently increased by introducing the array patterns without influencing its current-voltage (I-V) characteristics. Moreover, the electroluminescence spectra of a multi-color LED and its angular radiation profiles with orthogonal and hexagonal patterns also have been explored. In addition, the optical field distributions of the micro patterns simulated by the finite difference time domain method have expressed the modulation effect of the array depth. Finally, the patterned LED as a transmitter is embedded in the visible light communication system for evaluating the transmission signal quality.
14 citations
TL;DR: Two phase optical elements that are employed to generate approximate Bessel-Gauss beams of arbitrary order are compared and it is obtained that the error in the BBs generated with the kinoform is smaller than theerror in the beams obtained with the HA.
Abstract: We compare two phase optical elements that are employed to generate approximate Bessel–Gauss beams of arbitrary order. These elements are the helical axicon (HA) and the kinoform of the desired Bessel–Gauss beam. The HA generates a Bessel beam (BB) by free propagation, and the kinoform is employed in a Fourier spatial filtering optical setup. As the main result, it is obtained that the error in the BBs generated with the kinoform is smaller than the error in the beams obtained with the HA. On the other hand, it is obtained that the efficiencies of the methods are approximately 1.0 (HA) and 0.7 (kinoform).
14 citations
TL;DR: In this article, it was shown that in addition to well-known Bessel, Hermitte-Gauss and Laguerre Gauss beams of electromagnetic radiation, one may also construct exponential beams, characterized by a falloff in the transverse direction described by an exponential function of ρ.
Abstract: We show that in addition to well-known Bessel, Hermitte–Gauss and Laguerre–Gauss beams of electromagnetic radiation, one may also construct exponential beams. These beams are characterized by a fall-off in the transverse direction described by an exponential function of ρ. Exponential beams, like Bessel beams, carry definite angular momentum and are periodic along the direction of propagation, but unlike Bessel beams they have a finite energy per unit beam length. The analysis of these beams is greatly simplified by an extensive use of the Riemann–Silberstein vector and the Whittaker representation of the solutions of the Maxwell equations in terms of just one complex function. The connection between the Bessel beams and the exponential beams is made explicit by constructing the exponential beams as wave packets of Bessel beams.
14 citations
TL;DR: In this paper, the authors used the temporal change of electron density induced by femtosecond laser pulse for generating high aspect ratio nanoholes, where secondary pulses are irradiated from 100 to 1000ps after the irradiation of first pulse.
14 citations
TL;DR: In this paper, the authors investigated the properties of doubling the frequency of Bessel light beams by the Oe − e interaction in a KTP crystal and found that the energy conversion efficiency was 21% for a Bessel beam, which was three times higher than the efficiency of conversion of the initial laser beam.
Abstract: Theoretical and experimental investigations were made of the characteristic features of doubling the frequency of Bessel light beams by the oe — e interaction in a KTP crystal. All possible and scalar interactions of plane—wave components of Bessel beams were observed experimentally. The spatial structure of the second harmonic in the far zone consisted of a central spot and a concentric ring. The diffraction divergence of the central beam was weak ( ~ 1.7 mrad). The energy conversion efficiency was ~ 21% for a Bessel beam, which was three times higher than the efficiency of conversion of the initial laser beam. A theoretical model was based on representation of the field of the second harmonic as a superposition of Bessel beams, which provided a correct description of the observed spatial and energy characteristics of the second harmonic.
14 citations