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- Graham Gibson, Johannes Courtial, +4 authors Sonja Franke-Arnold
- Optics express
- 2004

We demonstrate the transfer of information encoded as orbital angular momentum (OAM) states of a light beam. The transmitter and receiver units are based on spatial light modulators, which prepare or measure a laser beam in one of eight pure OAM states. We show that the information encoded in this way is resistant to eavesdropping in the sense that any… (More)

- Jonathan Leach, Miles J Padgett, Stephen M Barnett, Sonja Franke-Arnold, Johannes Courtial
- Physical review letters
- 2002

We propose an interferometric method for measuring the orbital angular momentum of single photons. We demonstrate its viability by sorting four different orbital angular momentum states, and are thus able to encode two bits of information on a single photon. This new approach has implications for entanglement experiments, quantum cryptography and high… (More)

- Gregorius C G Berkhout, Martin P J Lavery, Johannes Courtial, Marco W Beijersbergen, Miles J Padgett
- Physical review letters
- 2010

We present a method to efficiently sort orbital angular momentum (OAM) states of light using two static optical elements. The optical elements perform a Cartesian to log-polar coordinate transformation, converting the helically phased light beam corresponding to OAM states into a beam with a transverse phase gradient. A subsequent lens then focuses each… (More)

- Jonathan Leach, Gavin Sinclair, +4 authors Zsolt Laczik
- Optics express
- 2004

We have developed holographic optical tweezers that can manipulate many particles simultaneously in three dimensions in order to create micro-crystal structures that extend over many tens of microns. The technique uses specific hologram-design algorithms to create structures that can be dynamically scaled or rotated about arbitrary axes. We believe the… (More)

- Jonathan Leach, Kurt Wulff, +8 authors Miles Padgett
- Applied optics
- 2006

We have developed software with an interactive user interface that can be used to generate phase holograms for use with spatial light modulators. The program utilizes different hologram design techniques, allowing the user to select an appropriate algorithm. The program can be used to generate multiple beams and can be used for beam steering. We see a major… (More)

- Gavin Sinclair, Pamela Jordan, Johannes Courtial, Miles Padgett, Jon Cooper, Zsolt Laczik
- Optics express
- 2004

The micromanipulation of objects into 3-dimensional geometries within holographic optical tweezers is carried out using modified Gerchberg-Saxton (GS) and direct binary search (DBS) algorithms to produce the hologram designs. The algorithms calculate sequences of phase holograms, which are implemented using a spatial light modulator, to reconfigure the… (More)

- Gavin Sinclair, Jonathan Leach, +5 authors Johannes Courtial
- Optics express
- 2004

Phase-hologram patterns that can shape the intensity distribution of a light beam in several planes simultaneously can be calculated with an iterative Gerchberg-Saxton algorithm [T. Haist et al., Opt. Commun. 140, 299 (1997)]. We apply this algorithm in holographic optical tweezers. This allows us to simultaneously trap several objects in individually… (More)

- J Leach, M R Dennis, J Courtial, M J Padgett
- 2004

Optical vortices generically arise when optical beams are combined. Recently, we reported how several laser beams containing optical vortices could be combined to form optical vortex loops, links and knots embedded in a light beam (Leach et al 2004). Here, we describe in detail the experiments in which vortex loops form these structures. The experimental… (More)

- Jonathan Leach, Johannes Courtial, Kenneth Skeldon, Stephen M Barnett, Sonja Franke-Arnold, Miles J Padgett
- Physical review letters
- 2004

We propose interferometric methods capable of measuring either the total angular momentum, or simultaneously measuring the spin and orbital angular momentum of single photons. This development enables the measurement of any angular momentum eigenstate of a single photon. The work allows the investigation of single-photon two-qubit entangled states and has… (More)

- M J Padgett, J Courtial
- Optics letters
- 1999

The polarization state of a light beam is related to its spin angular momentum and can be represented on the Poincaré sphere. We propose a sphere for light beams in analogous orbital angular momentum states. Using the Poincaré-sphere equivalent, we interpret the rotational frequency shift for light beams with orbital angular momentum [Phys. Rev. Lett. 80,… (More)