Laguerre-Gaussian mode sorter

Abstract

Exploiting a particular wave property for a particular application necessitates components capable of discriminating in the basis of that property. While spectral or polarisation decomposition can be straightforward, spatial decomposition is inherently more difficult and few options exist regardless of wave type. Fourier decomposition by a lens is a rare simple example of a spatial decomposition of great practical importance and practical simplicity; a two-dimensional decomposition of a beam into its linear momentum components. Yet this is often not the most appropriate spatial basis. Previously, no device existed capable of a two-dimensional decomposition into orbital angular momentum components, or indeed any discrete basis, despite it being a fundamental property in many wave phenomena. We demonstrate an optical device capable of decomposing a beam into a Cartesian grid of identical Gaussian spots each containing a single Laguerre-Gaussian component, using just a spatial light modulator and mirror.

Wavefront shaping in multimode fibers by transmission matrix engineering

“…In fact, if O(N 2 ) degrees of control are available, one can expect generating arbitrary N × N transformations between the input and output modes. Over the past two decades there is an ever-growing interest in realizing reconfigurable multimode transformations, for a wide range of applications, such as quantum photonic circuits [22,[31][32][33][34] optical communications [18,35], and nanophotonic processors [20,36]. These realizations require strong mixing of the input modes, as the output modes are arbitrary superpositions of the input modes.…”

Resolving starlight: a quantum perspective

“…quantum bound, but it is important to note that they scaled the quantum bound with respect to the diffracted photon number, not the photon number before the hologram, meaning that the result did not take into account the low diffraction efficiency of their hologram. Efficient SPADE is possible with multiple holograms however [89,99,100].…”

Scattering of light with angular momentum from an array of particles

“…A schematic showing the essential components of the type of experimental setup we envisage is shown in Fig. 1: with respect to the theory developed here, the key features are provided by the OAM sorters that determine the OAM of the incident beam and enable measurements of the distribution of the scattered field power over different OAM values [5][6][7][8][9][10]. This problem has several very dif- where an incident beam propagating along the directionk0 interacts with a distribution of particles within a cylindrical volume defined by the dimensions L ⊥ and L .…”

“…While scattering is considered to be detrimental for applications in information transfer, the ability to measure the power of the OAM states of the scattered light [5][6][7][8][9][10] may provide a source of information about the properties of the scattering medium, from the size and type of the particulates to their geometrical distribution, that has not yet been exploited. This may be of particular benefit for environmental sensing and metrology, and ocean transmissometry, and may even find applications in biological imaging.…”