Spatial coherence of light measured by nanoscattering

Kimmo Saastamoinen,Ismo Vartiainen,Tero Setälä,Lasse-Petteri Leppänen,Ari T Friberg

doi:10.1364/optica.5.000067

Abstract

As complex random electromagnetic fields are increasingly exploited in advanced photonics, the measurement of their statistical properties emerges as a crucial technical issue. For spatial coherence, we employ dipole scattering and report on a nano-optics counterpart of Young’s interferometer with the openings replaced by metallic dipolar nanoparticles. The results are in agreement with those obtained by other methods. The resolution is comparable to the size of the probes, well beyond that in standard techniques. While we consider here random optical beams, the two-probe method finds particular use in electromagnetic near-field optics where customary polarization elements cannot be employed.

Highlights

Spatial coherence is a fundamental property of light traditionally quantified by the visibility of the intensity fringes in Young’s double-slit interferometer [1,2]
Several approaches have been proposed for the determination of spatial coherence of light, including plasmonic devices [7], reversed-wavefront interferometers [8], and digital micromirror devices (DMD) [9]
The far fields generated in probe and pinhole techniques are produced by dipole scattering and aperture diffraction, respectively

Summary

Introduction

Spatial coherence is a fundamental property of light traditionally quantified by the visibility of the intensity fringes in Young’s double-slit interferometer [1,2]. Quite recently it was predicted that using two nanoparticle probes and observing the visibility of the intensity fringes that their scattered fields produce in the far zone yields the degree of spatial coherence of the light at the particle sites [10]. We demonstrate the first measurement of the spatial coherence of optical beams with nanoprobes.

Results

Conclusion