scholarly journals Influence of attenuation on the generation of optical vortices in multihelicoidal optical fibers

2021 ◽  
Vol 2103 (1) ◽  
pp. 012149
Author(s):  
C N Alexeyev ◽  
S S Alieva ◽  
E V Barshak ◽  
B P Lapin ◽  
M A Yavorsky
Keyword(s):  
Optical Fibers ◽  
Fundamental Mode ◽  
Optical Vortex ◽  
Conversion Process ◽  
Exceptional Point ◽  
Optical Vortices ◽  
Attenuation Coefficients ◽  
Enhanced Sensitivity ◽  
Scalar Approximation ◽  
The Difference

Abstract In this paper we have studied influence of attenuation on conversion processes of the fundamental mode (FM) in multihelicoidal optical fibers (MHF) in the vicinity of the point of accidental spectrum degeneracy within the framework of the scalar approximation. To this end, we have obtained expressions for modes of the MHF, which consist of the FM and an optical vortex (OV), and shown that conversion of the FM into the OV takes place. The difference in the attenuation coefficients for the partial fields of MHF’s modes leads to deterioration in the conversion process even with an ideal system’s tuning. At sufficiently large values of attenuation coefficients the conversion of the incoming FM into the vortex vanishes. Also we have shown the presence of exceptional point (EP) in the spectra of modes of the MHF and demonstrated enhanced sensitivity of the fiber in the vicinity of the EP to perturbations.

Optical vortices in fiber

Nanophotonics ◽  
2013 ◽  
Vol 2 (5-6) ◽  
pp. 455-474 ◽  
Author(s):  
Siddharth Ramachandran ◽  
Poul Kristensen
Keyword(s):  
Angular Momentum ◽  
Optical Fibers ◽  
Orbital Angular Momentum ◽  
Optical Vortex ◽  
Optical Vortices ◽  
New Class ◽  
Phase Singularities ◽  
Vortex Beams ◽  
Exotic Beams

AbstractOptical vortex beams, possessing spatial polarization or phase singularities, have intriguing properties such as the ability to yield super-resolved spots under focussing, and the ability to carry orbital angular momentum that can impart torque to objects. In this review, we discuss the means by which optical fibers, hitherto considered unsuitable for stably supporting optical vortices, may be used to generate and propagate such exotic beams. We discuss the multitude of applications in which a new class of fibers that stably supports vortices may be used, and review recent experiments and demonstration conducted with such fibers.

scholarly journals Optical Vortices: 3D Optical Vortex Lattices (Ann. Phys. 7/2021)

2021 ◽  
Vol 533 (7) ◽  
pp. 2170023
Author(s):  
Denis A. Ikonnikov ◽  
Sergey A. Myslivets ◽  
Vasily G. Arkhipkin ◽  
Andrey M. Vyunishev
Keyword(s):  
Optical Vortex ◽  
Optical Vortices ◽  
Vortex Lattices

scholarly journals Shaping Beam Profiles Using Plastic Optical Fiber Tapers with Application to Ice Sensors

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2503
Author(s):  
Kostas Amoiropoulos ◽  
Georgia Kioselaki ◽  
Nikolaos Kourkoumelis ◽  
Aris Ikiades
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Laser Cooling ◽  
Detection Efficiency ◽  
Numerical Aperture ◽  
Beam Profile ◽  
Hollow Beam ◽  
Enhanced Sensitivity ◽  
Surface Irregularities ◽  
Plastic Optical Fibers

Using either bulk or fiber optics the profile of laser beams can be altered from Gaussian to top-hat or hollow beams allowing enhanced performance in applications like laser cooling, optical trapping, and fiber sensing. Here, we report a method based on multimode Plastic Optical Fibers (POF) long-tapers, to tweak the beam profile from near Gaussian to a hollow beam, by generating surface irregularities on the conical sections of the taper with a heat-and-pull technique. Furthermore, a cutback technique applied on long tapers expanded the output beam profile by more than twice the numerical aperture (NA) of the fiber. The enhanced sensitivity and detection efficiency of the extended profile was tested on a fiber optical ice sensor related to aviation safety.

"Hybrid mode – linearly polarized optical vortex" transformation in multihelical optical fibers

2021 ◽  
Author(s):  
E. V. Barshak ◽  
D. V. Vikulin ◽  
B. P. Lapin ◽  
D. L. Puzankov ◽  
C. N. Alexeyev ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Optical Vortex ◽  
Hybrid Mode ◽  
Linearly Polarized

Torsional oscillation of a homogeneous elastic spheroid

1962 ◽  
Vol 52 (3) ◽  
pp. 469-484 ◽  
Author(s):  
Tatsuo Usami ◽  
Yasuo Satô
Keyword(s):  
Fundamental Mode ◽  
Free Oscillation ◽  
Torsional Oscillation ◽  
Numerical Calculations ◽  
Higher Harmonics ◽  
Oblate Spheroidal ◽  
The Earth ◽  
Spectral Peaks ◽  
The Difference ◽  
Spheroidal Coordinates

abstract There are several causes for the observations of splitting of the spectral peaks determined from the free oscillation of the earth. In this paper, the splitting due to the ellipticity is studied assuming a homogeneous earth described by oblate spheroidal coordinates. Ellipticity causes the iTn mode to split into (n + 1) modes, while the earth's rotation causes it to split into (2n + 1) modes. 1/297.0 is adopted as the ellipticity of the earth. Numerical calculations are carried out for the fundamental mode (n = 2, 3, 4) and for the first higher harmonics (n = 1). The difference between the extreme frequencies for each value of n is 0.7% (n = 2), 0.5% (n = 3), and 0.4% (n = 4).

scholarly journals Optical fibers as beam shapers: from Gaussian beams to optical vortices

2016 ◽  
Vol 41 (10) ◽  
pp. 2137 ◽  
Author(s):  
Rita S. Rodrigues Ribeiro ◽  
Pabitra Dahal ◽  
Ariel Guerreiro ◽  
Pedro Jorge ◽  
Jaime Viegas
Keyword(s):  
Optical Fibers ◽  
Gaussian Beams ◽  
Optical Vortices

Generation of optical vortices in non-PT-symmetric chiral-core optical fibers

2021 ◽  
Author(s):  
C. Alexeyev ◽  
Elena Barshak ◽  
Boris Lapin ◽  
Maxim Yavorsky
Keyword(s):  
Optical Fibers ◽  
Optical Vortices

scholarly journals Strongly Focused Circularly Polarized Optical Vortices Regulated by a Fractal Conical Lens

2019 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Zhirong Liu ◽  
Kelin Huang ◽  
Anlian Yang ◽  
Xun Wang ◽  
Philip H. Jones
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Numerical Aperture ◽  
Optical Element ◽  
Optical Vortex ◽  
Optical Vortices ◽  
Circularly Polarized ◽  
Strong Focusing ◽  
New Type ◽  
Vortex Beams

In this paper, a recently-proposed pure-phase optical element, the fractal conical lens (FCL), is introduced for the regulation of strongly-focused circularly-polarized optical vortices in a high numerical aperture (NA) optical system. Strong focusing characteristics of circularly polarized optical vortices through a high NA system in cases with and without a FCL are investigated comparatively. Moreover, the conversion between spin angular momentum (SAM) and orbital angular momentum (OAM) of the focused optical vortex in the focal vicinity is also analyzed. Results revealed that a FCL of different stage S could significantly regulate the distributions of tight focusing intensity and angular momentum of the circularly polarized optical vortex. The interesting results obtained here may be advantageous when using a FCL to shape vortex beams or utilizing circularly polarized vortex beams to exploit new-type optical tweezers.

scholarly journals Isotopic abundance of 13 C and contribution of eucalyptus biomass to soil organic matter conversion

2017 ◽  
Vol 47 (4) ◽  
Author(s):  
Fabiane Figueiredo Severo ◽  
Natália Tobin Aita ◽  
Laila Garcia Marques ◽  
Leandro Souza da Silva
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Natural Regeneration ◽  
Conversion Process ◽  
Initial Management ◽  
Natural Pasture ◽  
Crop Type ◽  
Isotope Ratio Mass Spectrometer ◽  
Native Tree Species ◽  
The Difference

ABSTRACT: It has become possible to evaluate the conversion of soil organic matter (SOM) in pastures and arboreal crops due to the difference between the photosynthetic cycles of Eucalyptus (C3) and most grasses (C4). The auto analyzer method coupled to the IRMS (Isotope Ratio Mass Spectrometer) in the present study evaluated the 13C content in soil profiles of Eucalyptus plantations of different ages (2, 10 and 21 years), in natural regeneration areas and natural grazing fields, and estimated the SOM conversion of each crop type of. The initial management of all sampled areas was natural pasture. The following profile layers were evaluated: 0-5, 5-10, 10-20, 20-30, 30-40, 40-50, 50-70 and 70-90cm, and the contribution of Eucalyptus biomass over the years of farming was estimated in the SOM conversion process. After 2 years of planting Eucalyptus, the beginning of pasture carbon conversion process occurred in the surface layer (0-5cm). Ten years after planting, the process of converting organic matter by arboreal crops reached the layers up to 20cm. After 21 years of planting and in natural regeneration areas, the entire profile has already been changed by planting Eucalyptus and native tree species.

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