scholarly journals Elliptical orbits of microspheres in an evanescent field

2017 ◽  
Vol 114 (42) ◽  
pp. 11087-11091 ◽  
Author(s):  
Lulu Liu ◽  
Simon Kheifets ◽  
Vincent Ginis ◽  
Andrea Di Donato ◽  
Federico Capasso
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Particle Motion ◽  
Optical Trap ◽  
Evanescent Field ◽  
Applied Force ◽  
Anisotropic Fluid ◽  
Rich Variety ◽  
Periodically Driven ◽  
Elliptical Orbits

We examine the motion of periodically driven and optically tweezed microspheres in fluid and find a rich variety of dynamic regimes. We demonstrate, in experiment and in theory, that mean particle motion in 2D is rarely parallel to the direction of the applied force and can even exhibit elliptical orbits with nonzero orbital angular momentum. The behavior is unique in that it depends neither on the nature of the microparticles nor that of the excitation; rather, angular momentum is introduced by the particle’s interaction with the anisotropic fluid and optical trap environment. Overall, we find this motion to be highly tunable and predictable.

Development of Precision Optical Traps for Single Molecule and Motor Protein Research

2004 ◽  
Author(s):  
Kurt D. Wulff ◽  
Daniel G. Cole ◽  
Robert L. Clark
Keyword(s):  
Angular Momentum ◽  
Laser Beam ◽  
Orbital Angular Momentum ◽  
Single Molecule ◽  
Optical Trap ◽  
Motor Protein ◽  
Optical Traps ◽  
Position Sensing ◽  
Intensity Field ◽  
Increased Sensitivity

Optical traps have become an important instrument for investigating systems and processes at the micro- and nanoscale, particularly within biology where manipulation of biological systems from DNA to cells has offered new insights to cellular processes. Using the inherent momentum of light, particles are trapped in the high intensity field of a focused laser beam thus allowing for the manipulation of microscopic particles. This paper discusses the current development of a state-of-the-art optical trap with increased sensitivity for the measurement of single molecule and motor protein mechanics. A common position sensing technique uses quadrant photodiodes to detect motion on the order of tens of nanometers. However, the measurement of positions and forces on a smaller level than previously attempted requires increased precision. Interferometric techniques provide one method to improve the spatial resolution to the order of nanometers or less. Furthermore, the use of feedback control offers the ability to easily adapt the optical trap to the particular experiment being conducted. In addition, optical traps can apply torque to trapped objects for the study of rotary mechanics when the trapping laser has orbital angular momentum. Methods for generating a laser beam with orbital angular momentum will be discussed.

scholarly journals Orbital angular momentum of Liénard–Wiechert fields

2019 ◽  
Vol 2019 (8) ◽  
Author(s):  
H Kawaguchi ◽  
M Katoh
Keyword(s):  
Electromagnetic Field ◽  
Angular Momentum ◽  
Charged Particle ◽  
Periodic Orbit ◽  
Radiation Field ◽  
General Expression ◽  
Orbital Angular Momentum ◽  
Particle Motion ◽  
Charged Particles ◽  
Relativistic Charged Particle

Abstract We derive a general expression for the electromagnetic field radiated by a relativistic charged particle with arbitrary periodic orbit, in the form of multi-pole expansion of the Liénard–Wiechert potential, which explicitly includes the charged particle motion. Using this expression, we discuss the orbital angular momentum radiated from a relativistic charged particle. It has recently been indicated that the radiation emitted by circularly orbiting charged particles carries well-defined orbital angular momentum. We show that, even for the general cases of arbitrary periodic orbits, the radiation field possesses well-defined orbital angular momentum.

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

Highly dispersive coupled ring-core fiber for orbital angular momentum modes

2020 ◽  
Vol 117 (19) ◽  
pp. 191101
Author(s):  
Wenpu Geng ◽  
Yiqiao Li ◽  
Yuxi Fang ◽  
Yingning Wang ◽  
Changjing Bao ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Core Fiber ◽  
Ring Core

scholarly journals Modal coupling and crosstalk due to turbulence and divergence on free space THz links using multiple orbital angular momentum beams

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhe Zhao ◽  
Runzhou Zhang ◽  
Hao Song ◽  
Kai Pang ◽  
Ahmed Almaiman ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Orbital Angular Momentum ◽  
Beam Waist ◽  
Modal Coupling ◽  
Divergence Effect ◽  
Power Leakage ◽  
Calm Weather ◽  
Bad Weather

AbstractOrbital-angular-momentum (OAM) multiplexing has been utilized to increase the channel capacity in both millimeter-wave and optical domains. Terahertz (THz) wireless communication is attracting increasing attention due to its broadband spectral resources. Thus, it might be valuable to explore the system performance of THz OAM links to further increase the channel capacity. In this paper, we study through simulations the fundamental system-degrading effects when using multiple OAM beams in THz communications links under atmospheric turbulence. We simulate and analyze the effects of divergence, turbulence, limited-size aperture, and misalignment on the signal power and crosstalk of THz OAM links. We find through simulations that the system-degrading effects are different in two scenarios with atmosphere turbulence: (a) when we consider the same strength of phasefront distortion, faster divergence (i.e., lower frequency; smaller beam waist) leads to higher power leakage from the transmitted mode to neighbouring modes; and (b) however, when we consider the same atmospheric turbulence, the divergence effect tends to affect the power leakage much less, and the power leakage increases as the frequency, beam waist, or OAM order increases. Simulation results show that: (i) the crosstalk to the neighbouring mode remains < − 15 dB for a 1-km link under calm weather, when we transmit OAM + 4 at 0.5 THz with a beam waist of 1 m; (ii) for the 3-OAM-multiplexed THz links, the signal-to-interference ratio (SIR) increases by ~ 5–7 dB if the mode spacing increases by 1, and SIR decreases with the multiplexed mode number; and (iii) limited aperture size and misalignment lead to power leakage to other modes under calm weather, while it tends to be unobtrusive under bad weather.

scholarly journals Switchable X-Ray Orbital Angular Momentum from an Artificial Spin Ice

2021 ◽  
Vol 126 (11) ◽  
Author(s):  
Justin S. Woods ◽  
Xiaoqian M. Chen ◽  
Rajesh V. Chopdekar ◽  
Barry Farmer ◽  
Claudio Mazzoli ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Spin Ice ◽  
X Ray ◽  
Artificial Spin Ice
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