We numerically model the propagation of light through a Kerr medium and through a far-red-detuned Bose Einstein condensate (BEC) inside an optical cavity using Lugiato-Lefever and Gross-Pitaevskii equations. We demonstrate the formation of light-atomic ring lattices with rotation speeds and direction that can be controlled by the orbital angular momentum of the light. In the BEC, we show the possibility of moving from a lattice to a ring-shaped atomic circuit by changing the atomic scattering length, and explore the potential generation of rotating BEC cavity solitons. Our results may be of interest as slow light pulses with fully controllable speed and structure for use in optical quantum memories, for particle manipulation and trapping, and for the novel realization of highly controllable, tightly confined, rotating atomic lattices.
We numerically model the propagation of far-detuned optical beams through a Bose-Einstein condensate (BEC) using coupled nonlinear Schr¨odinger and Gross-Pitaevskii equations. For red atom-field detuning, we show that light carrying orbital angular momentum (OAM) can lead to coupled light-atom solitons carrying angular momentum. We demonstrate the formation of azimuthally rotating wavepackets, toward an atomic persistent current without trapping requirements. For blue atom-field detuning, we show highly exotic BEC distributions, with the atoms trapped in dark regions of the optical field. Our results provide a novel means of atomic transport and of sculpting a BEC into unique transverse distributions.
The drive for high-bandwidth, secure communications links has led to space-division-multiplexing (SDM) becoming a burgeoning area of study, where multiplexing independent spatial channels can act to increase the capacity of communication links. SDM techniques implemented in systems employing both optical and radiofrequency carriers have recently received interest from the community for use within point-to-point communication links, particularly in long distance fibre links [1– 3]. Many of these studies have driven the development of tools and technologies for the efficient collection and processing of the light carrying spatial information that can be repurposed for novel sensing applications. Localised heating, suspended particles, turbidity and mechanical mixing, such as moving air or flowing water, all result in degradation of the optical field [4, 6]. The specific degradation that occurs over the channel can reveal important information about the physical properties of the environment the beam have propagated through.
Structured light can enhance the functionality of optical communication and sensing systems. Dense scattering environments such as those experienced in coastal water or foggy conditions result in degradation of structured optical fields. We present findings that indicate the preservation of phase structure of beams for Ballistic Light carrying Orbital Angular Momentum (OAM) propagated through a dense scattering over short (<3m) distance with attention of up to 20dB. We present a numerical channel modelling approach that can predict the scattering behaviour at extended distances, which indicate that there is a strong mode dependant variance in crosstalk from the interaction of beams that carry OAM with randomly displaced scattering particles. These result present an exciting possibility to use OAM modes as a long distance particulate sensor and could potentially lead to the development of novel tools for monitoring the particles in the environment.
Fully-structured light, light with non-uniform intensity, phase and polarization, lies at the heart of an extremely promising field of research, with applications in high-resolution imaging and optical trapping and manipulation of nanoparticles. Such fields are readily constructed from superpositions of two orthogonally polarized Laguerre-Gaussian modes carrying different orbital angular momentum (OAM). This opens new possibilities in engineering complex light distributions for specific applications.
We simulate the propagation of fully-structured light in a self-focusing nonlinear medium using a coupled two-dimensional nonlinear Schrödinger equation with saturable self-focusing nonlinearity and show that the spatial structure of the polarization can be used to control both the collapse dynamics of the beams [1] and the amount of polarisation rotation. These findings provide a novel approach to transport high-power light beams in nonlinear media with controllable distortions to their spatial structure and polarization properties.
Complex light can also have non-uniform helicity density and the resultant gradients in helicity density will generate a force that will interact differently with opposite enantiomers of chiral molecules [2]. Here we demonstrate how the energy and helicity gradients in the fields, and the corresponding dipole and chiral forces, can be engineered for specific applications. We also investigate the use of nonlinearity to control and manipulate the spatially-varying chiral force.
[1] F. Bouchard et al., Phys. Rev. Lett 117, 233903 (2016)
[2] R. Cameron et al., New J. Phys. 16, 013020 (2014)
We have developed a new approach to measuring the spatial position of a single photon. Using fibers of different
length, all connected to a single detector allows us to use the high timing precision of single photon avalanche diodes
(SPAD) to spatially locate the photon. We have built two 8-element detector arrays to measure the full-field quantum
correlations in position, momentum and intermediate bases for photon pairs produced in parametric down conversion.
The strength of the position-momentum correlations is found to be an order of magnitude below the classical limit.
We demonstrate the use of holographic optical tweezers to form arrangements of silica beads for trapping and
measuring the mechanical properties of micron sized objects, such as oil droplets and yeast cells. This allows
us to investigate the mechanical properties of the constrained object, which need not be optically trapped itself
(thus preventing radiation damage and allowing objects with a low refractive index to be constrained). By
compressing the object with the beads we are able to determine the size of the trapped object and show that
there is an elastic coupling between the beads due to the presence of a trapped object. We expect more detailed
analysis of the system will allow mechanical and frequency-dependent viscoelastic properties of objects to be
investigated.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.