High Discrimination Ratio, Broadband Circularly Polarized Light Photodetector Using Dielectric Achiral Nanostructures

TL;DR

This paper introduces a broadband circularly polarized light photodetector using achiral dielectric nanostructures, achieving a high discrimination ratio and enabling effective on-chip polarization sensing without calibration.

Contribution

The study presents a novel achiral dielectric nanostructure design for broadband CPL detection with significantly improved discrimination ratio, advancing integrated polarization sensing technology.

Findings

Discrimination ratio of ~107 at 405 nm wavelength

Effective CPL discrimination across the visible spectrum

No need for intensity calibration

Abstract

The on-chip measurement of polarization states plays an increasingly crucial role in modern sensing and imaging applications. While high-performance monolithic linearly polarized photodetectors have been extensively studied, integrated circularly polarized light (CPL) photodetectors are still hindered by inadequate discrimination capability. In this study, we employ achiral all-dielectric nanostructures to develop a broadband CPL photodetector with an impressive discrimination ratio of ~107 at the wavelength of 405 nm, significantly surpassing its counterparts by two orders of magnitude. Our device shows outstanding CPL discrimination capability across the visible band without requiring intensity calibration. Its function mechanism is based on the CPL-dependent near-field modes within achiral structures: under left or right CPL illumination, distinct near-field modes are excited, resulting in asymmetric irradiation of the two electrodes and generating a photovoltage with directions determined by the chirality of the incident light field. The proposed design strategy facilitates the realization of ultra-compact CPL detection across diverse materials, structures, and spectral ranges, presenting a novel avenue for achieving high-performance monolithic CPL detection.