Generalized Hartmann-Shack array of dielectric metalens sub-arrays for polarimetric beam profiling

TL;DR

This paper presents a compact metasurface-based array system for real-time polarization and phase profile measurement of optical beams, enhancing beam diagnostics with integrated metalens sub-arrays and wavefront sensing.

Contribution

It introduces a system of silicon-based metalens sub-arrays for simultaneous polarization and phase profiling, advancing compact and real-time optical beam diagnostics.

Findings

Achieved 28% diffraction efficiency at 1550 nm

Successfully diagnosed various polarization profiles

Enabled real-time beam diagnostics with a compact setup

Abstract

To define and characterize optical systems, obtaining information on the amplitude, phase, and polarization profile of optical beams is of utmost importance. Polarimetry using bulk optics is well established to characterize the polarization state. Recently, metasurfaces and metalenses have successfully been introduced as compact optical components. Here, we take the metasurface concept to the system level by realizing arrays of metalens 2*3 sub-arrays, allowing to determine the polarization profile of an optical beam. We use silicon-based metalenses with a numerical aperture of 0.32 and a mean measured diffraction efficiency in transmission mode of 28% at 1550 nm wavelength. Together with a standard camera recording the array foci, our system is extremely compact and allows for real-time beam diagnostics by inspecting the foci amplitudes. By further analyzing the foci displacements in the spirit of a Hartmann-Shack wavefront sensor, we can simultaneously detect phase-gradient profiles. As application examples, we diagnose the polarization profiles of a radially polarized beam, an azimuthally polarized beam, and of a vortex beam.