Hybrid coupled mode modelling of the evanescent excitation of a dielectric tube by semi-guided waves at oblique angles

2020 ◽  
Vol 52 (11) ◽  
Author(s):  
Manfred Hammer ◽  
Lena Ebers ◽  
Jens Förstner
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Guided Waves ◽  
Strong Field ◽  
Field Enhancement ◽  
Analytic Solutions ◽  
Slab Waveguide ◽  
Dielectric Tube ◽  
Coupled Mode ◽  
Evanescent Excitation

AbstractA dielectric step-index optical fiber with tube-like profile is considered, being positioned with a small gap on top of a dielectric slab waveguide. We propose a 2.5-D hybrid analytical/numerical coupled mode model for the evanescent excitation of the tube through semi-guided waves propagating in the slab at oblique angles. The model combines the directional polarized modes supported by the slab with analytic solutions for the TE-, TM-, and orbital-angular-momentum (OAM) modes of the tube-shaped fiber. Implementational details of the scheme are discussed, complemented by finite-element simulations for verification purposes. Our results include configurations with resonant in-fiber excitation of OAM modes with large orbital angular momentum and strong field enhancement.

scholarly journals Transmission and Generation of Orbital ANGULAR Momentum Modes in Optical Fibers

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 246
Author(s):  
Zhuo Wang ◽  
Jiajing Tu ◽  
Shecheng Gao ◽  
Zhaohui Li ◽  
Changyuan Yu ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Optical Fibers ◽  
Orbital Angular Momentum ◽  
Optical Communications ◽  
Coupled Mode Theory ◽  
The Novel ◽  
Fundamental Theory ◽  
Coupled Mode ◽  
Mode Stability ◽  
Fiber Modes

The orbital angular momentum (OAM) of light provides a new degree of freedom for carrying information. The stable propagation and generation of OAM modes are necessary for the fields of OAM-based optical communications and microscopies. In this review, we focus on discussing the novel fibers that are suitable for stable OAM mode transmission and conversion. The fundamental theory of fiber modes is introduced first. Then, recent progress on a multitude of fiber designs that can stably guide or generate OAM modes is reviewed. Currently, the mode crosstalk is regarded as the main issue that damages OAM mode stability. Therefore, the coupled-mode theory and coupled-power power theory are introduced to analyze OAM modes crosstalk. Finally, the challenges and prospects of the applications of OAM fibers are discussed.

scholarly journals Manipulating Twisted Electrons in Strong Field Ionization

2020 ◽  
Author(s):  
Andrew Maxwell ◽  
Gregory S J Armstrong ◽  
Marcelo Ciappina ◽  
Emilio Pisanty ◽  
Yuxin Kang ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Experimental Work ◽  
Strong Field ◽  
Alternative Interpretation ◽  
Field Ionization ◽  
Strong Field Ionization

We investigate the discrete orbital angular momentum of photoelectrons freed in strong-field ionization. We use these `twisted' electrons to provide an alternative interpretation on existing experimental work of vortex interferences...

scholarly journals Conservation laws for electron vortices in strong-field ionisation

2021 ◽  
Vol 75 (7) ◽  
Author(s):  
Yuxin Kang ◽  
Emilio Pisanty ◽  
Marcelo Ciappina ◽  
Maciej Lewenstein ◽  
Carla Figueira de Morisson Faria ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Conservation Laws ◽  
Orbital Angular Momentum ◽  
Strong Field ◽  
Emission Spectra ◽  
Bound State ◽  
Field Approximation ◽  
Photoelectron Spectra ◽  
Strong Laser Field ◽  
New Variant

Abstract We investigate twisted electrons with a well-defined orbital angular momentum, which have been ionised via a strong laser field. By formulating a new variant of the well-known strong field approximation, we are able to derive conservation laws for the angular momenta of twisted electrons in the cases of linear and circularly polarised fields. In the case of linear fields, we demonstrate that the orbital angular momentum of the twisted electron is determined by the magnetic quantum number of the initial bound state. The condition for the circular field can be related to the famous ATI peaks, and provides a new interpretation for this fundamental feature of photoelectron spectra. We find the length of the circular pulse to be a vital factor in this selection rule and, employing an effective frequency, we show that the photoelectron OAM emission spectra are sensitive to the parity of the number of laser cycles. This work provides the basic theoretical framework with which to understand the OAM of a photoelectron undergoing strong field ionisation. Graphic Abstract

Advanced Mode Unity Using Loop Antennas Proximate to Reflector for Orbital Angular Momentum Communication

2018 ◽  
Author(s):  
Ryohei Yamagishi ◽  
Hiroto Otsuka ◽  
Ryo Ishikawa ◽  
Akira Saitou ◽  
Hiroshi Suzuki ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Loop Antennas
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