吸收介质中的抗衍射衰减光束

抗衍射衰减光束的高阶形式和光阑产生

Diffraction-Attenuation Resistant Beams: their Higher Order Versions and Finite-Aperture Generations

近年来，通过理想零阶贝塞尔光束的适当叠加，发展了一种在吸收介质中获得抗衍射衰减光束的方法。在这项工作中，我们将表明，这样的光束保持其阻力衍射和吸收，即使当产生的有限孔径。此外，我们将扩展原来的方法，以允许更高的控制光束的横向强度分布。虽然该方法是针对标量场发展起来的，但它也可以应用于傍轴矢量波场。这些新光束在自由空间光学、医学仪器、遥感、光镊等方面具有潜在的应用价值。

Fusion Between Frozen-Wave-Type Beams and Airy-Type Pulses: Diffraction-Dispersion-Attenuation Resistant Vortex Pulses in Absorbing Media

In this paper we perform a fusion between two important theoretical methodologies, one related to the Frozen Wave beams, which are non-diffracting beams whose longitudinal intensity pattern can be chosen a priori in an medium (absorbing or not), and the other related to the Airy-Type pulses, which are pulses resistant to dispersion effects in dispersive materials. As a result, a new method emerges, capable of providing vortex pulses resistant to three concomitant effects, i.e.: diffraction, dispersion and attenuation; while concurrently the spatial variation of the wave intensity along its axi…

Arbitrary control of the polarization and intensity profiles of diffraction-attenuation-resistant beams along their propagation direction

We report on the theory and experimental generation of a class of diffraction-attenuation-resistant beams with state of polarization (SoP) and intensity that can be controlled on demand along the propagation direction. This is achieved by a suitable superposition of Bessel beams, whose parameters are systematically chosen based on closed-form analytic expressions provided by the Frozen Waves (FWs) method. Using an amplitude-only spatial light modulator, we experimentally demonstrate three scenarios. In the first, the SoP of a horizontally polarized beam evolves to radial polarization and is th…

Tailoring Instantaneous Time Mirrors for Time Reversal Focusing in Absorbing Media

The time reversal symmetry of the wave equation allows wave refocusing back at the source. However, this symmetry does not hold in lossy media. We present a new strategy to compensate wave amplitude losses due to attenuation. The strategy leverages the instantaneous time mirror (ITM) which generates reversed waves by a sudden disruption of the medium properties. We create a heterogeneous ITM whose disruption is unequal throughout the space to create waves of different amplitude. The time-reversed waves can then cope with different attenuation paths as typically seen in heterogeneous and lossy …

Modelling the longitudinal intensity pattern of diffraction resistant beams in stratified media

In this paper, we study the propagation of the Frozen Wave type beams through non-absorbing stratified media and develop a theoretical method capable to provide the desired spatially shaped diffraction resistant beam in the last material medium. In this context, we also develop a matrix method to deal with stratified media with large number of layers. Additionally, we undertake some discussion about minimizing reflection of the incident FW beam on the first material interface by using thin films. Our results show that it is indeed possible to obtain the control, on demand, of the longitudinal …

Optical vortex trapping and annihilation by means of nonlinear Bessel beams in nonlinearly absorbing media

In nonlinear Kerr media at intensities such that multiphoton absorption is significant, a vortex of topological charge m in the center of a high-order nonlinear Bessel beam (NBB) can be stable and subsist endlessly. We show that the m-charged NBB is not only stable but is formed spontaneously from any other n-charged NBB and N "foreign" vortices of total charge s randomly nested in the beam cross section if n + s = m. All nested vortices merge in the center of the original NBB, which undergoes a mode conversion to the NBB that preserves the topological charge and the inward-directed power curr…