Arbitrarily tunable orbital angular momentum of photons

Abstract

Orbital angular momentum (OAM) of photons, as a new fundamental degree of freedom, has excited a great diversity of interest, because of a variety of emerging applications. Arbitrarily tunable OAM has gained much attention, but its creation remains still a tremendous challenge. We demonstrate the realization of well-controlled arbitrarily tunable OAM in both theory and experiment. We present the concept of general OAM, which extends the OAM carried by the scalar vortex field to the OAM carried by the azimuthally varying polarized vector field. The arbitrarily tunable OAM we presented has the same characteristics as the well-defined integer OAM: intrinsic OAM, uniform local OAM and intensity ring, and propagation stability. The arbitrarily tunable OAM has unique natures: it is allowed to be flexibly tailored and the radius of the focusing ring can have various choices for a desired OAM, which are of great significance to the benefit of surprising applications of the arbitrary OAM.

Extreme Ultraviolet Fractional Orbital Angular Momentum Beams from High Harmonic Generation

“…Interestingly, it has been recently shown that light beams can carry fractional or non-integer OAM, i.e., photons can exhibit a half-integer angular momentum 3 4 5 6 7 8 9 10 . In this sense, conical refraction (CR) produced with optically biaxial crystals has been demonstrated to be an efficient method to generate half-integer OAM beams 11 12 13 14 15 .…”

Ultrafast control of fractional orbital angular momentum of microlaser emissions

“…For example, this feature leads to an increase in the modulation spectral efficiency, yielding higher bit rates for the same total bandwidth, as it can enable M-ary modulations in analogy to the well-established quadrature amplitude modulation scheme 17 . The generation of optical beams carrying FOAM is similar to the simultaneous generation of at least two copropagating OAM beams of different amplitudes, mainly relying on carefully aligned tabletop optical setups involving a noninteger spiral phase plate, a geometric-phase-designed J plate, metasurfaces, or a spatial light modulator [18][19][20][21][22][23][24] . The desired FOAM can be generated by delicately tuning the weighting between two distinguished OAM components.…”

Photons, Orbital Angular Momentum, and Neutrons

“…Using an iris on a translation stage, adjustable perpendicular to the beam, we create a beam with restricted transverse coherence and show that the presence of an OAM state is dependent on the transverse coherence. The creation of fractional OAM states by such a technique is well known in the photon optical community, [14] but here we are interested in integer OAM states. After reviewing specifics of coherence and OAM states, we present our setup and main results.…”