scholarly journals Transfer of ‘pure’ on-axis spin angular momentum to the absorptive particle using self-imaged bottle beam optical tweezers system

2004 ◽  
Vol 12 (21) ◽  
pp. 5172 ◽  
Author(s):  
B. P. S. Ahluwalia ◽  
X.-C. Yuan ◽  
S. H. Tao
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Spin Angular Momentum

scholarly journals Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices

2016 ◽  
Vol 2 (9) ◽  
pp. e1600485 ◽  
Author(s):  
Li He ◽  
Huan Li ◽  
Mo Li
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Laser Cooling ◽  
Photonic Devices ◽  
Mechanical Effect ◽  
Linear Momentum ◽  
Polarization Degree ◽  
Optical Forces ◽  
Spin Angular Momentum ◽  
Optical Torque

Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon’s polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry.

scholarly journals Photokinetic analysis of the forces and torques exerted by optical tweezers carrying angular momentum

2017 ◽  
Vol 375 (2087) ◽  
pp. 20150432 ◽  
Author(s):  
Aaron Yevick ◽  
Daniel J. Evans ◽  
David G. Grier
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Optical Traps ◽  
Gradient Term ◽  
Strength Anisotropy ◽  
Spin Angular Momentum ◽  
Intensity Gradient ◽  
First Order ◽  
Interference Contribution ◽  
Focused Beam

The theory of photokinetic effects expresses the forces and torques exerted by a beam of light in terms of experimentally accessible amplitude and phase profiles. We use this formalism to develop an intuitive explanation for the performance of optical tweezers operating in the Rayleigh regime, including effects arising from the influence of light’s angular momentum. First-order dipole contributions reveal how a focused beam can trap small objects, and what features limit the trap’s stability. The first-order force separates naturally into a conservative intensity-gradient term that forms a trap and a non-conservative solenoidal term that drives the system out of thermodynamic equilibrium. Neither term depends on the light’s polarization; light’s spin angular momentum plays no role at dipole order. Polarization-dependent effects, such as trap-strength anisotropy and spin-curl forces, are captured by the second-order dipole-interference contribution to the photokinetic force. The photokinetic expansion thus illuminates how light’s angular momentum can be harnessed for optical micromanipulation, even in the most basic optical traps. This article is part of the themed issue ‘Optical orbital angular momentum’.

Introduction of spin torques

2017 ◽  
Author(s):  
T. Kimura
Keyword(s):  
Angular Momentum ◽  
Giant Magnetoresistance ◽  
Spontaneous Magnetization ◽  
Magnetic Domain ◽  
Magnetic Multilayers ◽  
Transfer Effect ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Angular Momentum ◽  
Spin Torques

This chapter discusses the spin-transfer effect, which is described as the transfer of the spin angular momentum between the conduction electrons and the magnetization of the ferromagnet that occurs due to the conservation of the spin angular momentum. L. Berger, who introduced the concept in 1984, considered the exchange interaction between the conduction electron and the localized magnetic moment, and predicted that a magnetic domain wall can be moved by flowing the spin current. The spin-transfer effect was brought into the limelight by the progress in microfabrication techniques and the discovery of the giant magnetoresistance effect in magnetic multilayers. Berger, at the same time, separately studied the spin-transfer torque in a system similar to Slonczewski’s magnetic multilayered system and predicted spontaneous magnetization precession.

scholarly journals Optical vortex lattice: an exploitation of orbital angular momentum

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Liuhao Zhu ◽  
Miaomiao Tang ◽  
Hehe Li ◽  
Yuping Tai ◽  
Xinzhong Li
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Orbital Angular Momentum ◽  
Vortex Lattice ◽  
Optical Vortex ◽  
Yeast Cells ◽  
Particle Manipulation ◽  
Complex Motion ◽  
Potential Applications ◽  
Vortex Beams

Abstract Generally, an optical vortex lattice (OVL) is generated via the superposition of two specific vortex beams. Thus far, OVL has been successfully employed to trap atoms via the dark cores. The topological charge (TC) on each optical vortex (OV) in the lattice is only ±1. Consequently, the orbital angular momentum (OAM) on the lattice is ignored. To expand the potential applications, it is necessary to rediscover and exploit OAM. Here we propose a novel high-order OVL (HO-OVL) that combines the phase multiplication and the arbitrary mode-controllable techniques. TC on each OV in the lattice is up to 51, which generates sufficient OAM to manipulate microparticles. Thereafter, the entire lattice can be modulated to desirable arbitrary modes. Finally, yeast cells are trapped and rotated by the proposed HO-OVL. To the best of our knowledge, this is the first realization of the complex motion of microparticles via OVL. Thus, this work successfully exploits OAM on OVL, thereby revealing potential applications in particle manipulation and optical tweezers.

Accretion of Mass and Spin Angular Momentum by a Planet on an Eccentric Orbit

Icarus ◽  
1997 ◽  
Vol 127 (1) ◽  
pp. 65-92 ◽  
Author(s):  
Jack J. Lissauer ◽  
Alice F. Berman ◽  
Yuval Greenzweig ◽  
David M. Kary
Keyword(s):  
Angular Momentum ◽  
Spin Angular Momentum ◽  
Eccentric Orbit

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 Relation Between Star Formation and Angular Momentum in Spiral Galaxies

1983 ◽  
Vol 100 ◽  
pp. 135-136
Author(s):  
L. Carrasco ◽  
A. Serrano
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Radial Distribution ◽  
Spiral Galaxies ◽  
Formation Rate ◽  
Inverse Function ◽  
Solar Neighborhood ◽  
Spin Angular Momentum ◽  
Stellar Formation ◽  
The Galaxy

We derive the radial distribution of the specific angular momentum j=J/M, for the gas in M31, M51 and the galaxy, objects for which well observed unsmoothed rotation curves are available in the literature. We find the specific angular momentum to be anti-correlated with the present stellar formation rate, i.e. minima of spin angular momentum correspond to the loci of spiral arms. We find that the stellar formation rate is an inverse function of j. We derive new values of Oort's A constant for the arm and interarm regions in the solar neighborhood.

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