Direct Light Orbital Angular Momentum Detection in Mid-Infrared based on Type-II Weyl Semimetal TaIrTe4

TL;DR

This paper demonstrates a novel mid-infrared photodetector based on Type-II Weyl semimetal TaIrTe4 that can directly detect the orbital angular momentum of light, enabling advanced imaging and sensing applications.

Contribution

The study introduces a new mid-infrared OAM detection method using topological Weyl semimetal TaIrTe4 with designed electrodes, overcoming previous phase sensitivity and responsivity limitations.

Findings

Successfully detected OAM in mid-infrared using TaIrTe4

Observed current winding proportional to OAM mode number

Enhanced mid-infrared responsivity enables practical applications

Abstract

The capability of direct photocurrent detection of orbital angular momentum (OAM) of light has recently been realized with topological Weyl semimetal, but limited to near infrared wavelength range. The extension of direct OAM detection to midinfrared, a wavelength range that plays important role in a vast range of applications, such as autonomous driving, night vision and motion detection, is challenging and has not yet been realized. This is because most studies of photocurrent responses are not sensitive to the phase information and the photo response is usually very poor in the mid-infrared. In this study, we designed a photodetector based on Type-II Weyl semimetal tantalum iridium tellurides with designed electrode geometries for direct detection of the topological charge of OAM through orbital photogalvanic effect. Our results indicate helical phase gradient of light can be distinguished by a current winding around the optical beam axis with a magnitude proportional to its quantized OAM mode number. The topological enhanced response at mid-infrared of TaIrTe4 further help overcome the low responsivity issues and finally render the direct orbital angular momentum detection capability in mid-infrared. Our study enables on-chip integrated OAM detection, and thus OAM sensitive focal plane arrays in mid-infrared. Such capability triggers new route to explore applications of light carrying OAM, especially that it can crucially promote the performance of many mid-infrared imaging related applications, such as intricate target recognition and night vision.