Book contents
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 Light beams carrying orbital angular momentum
- 2 Vortex transformations and vortex dynamics in optical fields
- 3 Vector beams in free space
- 4 Optical beams with orbital angular momentum in nonlinear media
- 5 Ray optics, wave optics and quantum mechanics
- 6 Quantum formulation of angle and orbital angular momentum
- 7 Dynamical rotational frequency shift
- 8 Spin-orbit interactions of light in isotropic media
- 9 Quantum electrodynamics, angular momentum and chirality
- 10 Trapping of charged particles by Bessel beams
- 11 Theory of atoms in twisted light
- 12 An experimentalist's introduction to orbital angular momentum for quantum optics
- 13 Measurement of light's orbital angular momentum
- 14 Efficient generation of optical twisters using helico-conical beams
- 15 Self-similar modes of coherent diffusion with orbital angular momentum
- 16 Quantum entanglement of orbital angular momentum
- Index
- References
13 - Measurement of light's orbital angular momentum
Published online by Cambridge University Press: 05 December 2012
- Frontmatter
- Contents
- List of contributors
- Preface
- 1 Light beams carrying orbital angular momentum
- 2 Vortex transformations and vortex dynamics in optical fields
- 3 Vector beams in free space
- 4 Optical beams with orbital angular momentum in nonlinear media
- 5 Ray optics, wave optics and quantum mechanics
- 6 Quantum formulation of angle and orbital angular momentum
- 7 Dynamical rotational frequency shift
- 8 Spin-orbit interactions of light in isotropic media
- 9 Quantum electrodynamics, angular momentum and chirality
- 10 Trapping of charged particles by Bessel beams
- 11 Theory of atoms in twisted light
- 12 An experimentalist's introduction to orbital angular momentum for quantum optics
- 13 Measurement of light's orbital angular momentum
- 14 Efficient generation of optical twisters using helico-conical beams
- 15 Self-similar modes of coherent diffusion with orbital angular momentum
- 16 Quantum entanglement of orbital angular momentum
- Index
- References
Summary
Introduction
The orbital angular momentum (OAM) carried by light is widely seen as an extremely useful optical characteristic, with applications in many areas of optics. It was Allen et al. [1] who recognised that a helically phased light beam with a phase cross-section of exp(iℓϕ) carries an OAM, with a value of ℓℏ per photon. Such a light beam contains an optical vortex line of ℓ on its axis. One issue that is yet to be completely resolved is the development of a simple and 100% efficient method for the measurement of OAM.
A better known case of optical angular momentum is spin angular momentum (SAM). SAM is associated with the polarisation state of the light; the spin angular momentum in a left and right circularly polarised beam is σℏ=±1, per photon, respectively [2]. The SAM can be easily determined through the use of a polarising beam splitter, where a π/4 waveplate converts circular polarised light into a p- or s-polarised state which is then transmitted or reflected to give one of two outputs, as shown in Fig. 13.1(a).
OAM arises from the amplitude cross-section of the beam and is therefore independent of the spin angular momentum. One key characteristic of beams carrying OAM is that whereas SAM has only two orthogonal states, the OAM is described by an unbounded state space, i.e. ℓ (as in exp(iℓϕ) can take any integer value [3].
- Type
- Chapter
- Information
- The Angular Momentum of Light , pp. 330 - 351Publisher: Cambridge University PressPrint publication year: 2012
References
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