Vortex-free phase profiles for uniform patterning with computer-generated holography

Abstract

Computer-generated holography enables efficient light pattern generation through phase-only wavefront modulation. While perfect patterning usually requires control over both phase and amplitude, iterative Fourier transform algorithms (IFTA) can achieve phase-only approximations which maximize light efficiency at the cost of uniformity. The phase being unconstrained in the output plane, it can vary abruptly in some regions leading to destructive interferences. Among such structures phase vortices are the most common. Here we demonstrate theoretically, numerically and experimentally, a novel approach for eliminating phase vortices by spatially filtering the phase input to the IFTA, combining it with phase-based complex amplitude control at the spatial light modulator (SLM) plane to generate smooth shapes. The experimental implementation is achieved performing complex amplitude modulation with a phase-only SLM. This proposed experimental scheme offers a continuous and centered field of excitation. Lastly, we characterize achievable trade-offs between pattern uniformity, diffraction efficiency, and axial confinement.

Introducing non-local correlations into laser speckles

“…Previous studies dedicated to altering speckle intensity correlations [26][27][28][29][30][31][32][33][34][35] generally rely on the Siegert relation, and modulate the spatial field correlations. It is more challenging to violate the Siegert relation and control the intensity correlations without affecting the field correlations.…”

Visible-broadband Localized Vector Vortex Beam Generator with a Multi-structure-composited Meta-surface

“…Vector vortex beams that carry orbital angular momentum [ 1 , 2 , 3 , 4 ] are widely utilized in particle manipulation and separation [ 5 , 6 , 7 ], optical communication [ 8 , 9 , 10 , 11 ], quantum computing [ 12 , 13 ] and even light-driven micro-tools [ 14 ]. Formerly, vortex beams were tuned by spiral phase plates [ 15 , 16 ], spatial light modulators [ 17 , 18 ] and computer-generated holograms [ 19 , 20 ]. Nowadays, meta-surfaces [ 21 , 22 , 23 , 24 , 25 ] are utilized to generate optical fields for the integration and miniaturization of optical components.…”

Customizing speckle intensity statistics

“…There has been a plethora of interest in creating speckle patterns with tailored statistics [14][15][16][17][18][19][20][21][22][23] due to their potential applications in structured-illumination imaging; for example: dynamic speckle illumination microscopy [24,25], super-resolution imaging [26,27], and pseudo-thermal light sources for highorder ghost imaging [28][29][30]. Furthermore, a general method for customizing both the statistics and topology of laser speckle patterns would be a valuable tool for synthesizing optical potentials for cold atoms [31], microparticles [32][33][34][35], and active media [36][37][38].…”