Direct Light Orbital Angular Momentum Detection in Mid‐Infrared Based on the Type‐II Weyl Semimetal TaIrTe₄

Abstract

The direct photocurrent detection capability of light orbital angular momentum (OAM) has recently been realized with topological Weyl semimetals, but it is limited to the near‐infrared wavelength range. The extension of the direct OAM detection capability to the mid‐infrared band, which is a wave band that plays an important role in a vast range of applications, has not yet been realized. This is because the photocurrent responses of most photodetectors are neither sensitive to the phase information nor efficient in the mid‐infrared region. In this study, a photodetector based on the type‐II Weyl semimetal tantalum iridium telluride (TaIrTe4) is designed with peculiar electrode geometries to directly detect the topological charge of the OAM using the orbital photogalvanic effect (OPGE). The results indicate that the 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 topologically enhanced responses in the mid‐infrared region of TaIrTe4 further help overcome the low responsivity issues and finally render direct OAM detection capability. This study enables on‐chip‐integrated OAM detection, and thus OAM‐sensitive focal plane arrays in the mid‐infrared region.

Light control with Weyl semimetals

“…[82, §24] for detailed derivation of Eq. (10). Now, we introduce the formalism of axion electrodynamics [83].…”

“…In Ref. [10], Lai et al demonstrate the generation of orbital photocurrents in the mid-infrared wavelengths with another Weyl semimetal TaIrTe 4 .…”

“…Besides these fundamental interests, Weyl semimetals may also enable new opportunities in practical applications. For example, photonic applications include compact optical isolators and circulators [6][7][8], orbital angular momentum detectors [9,10], higher-order harmonic generation [11][12][13], and nonreciprocal thermal emitters [14][15][16] among many others. However, such an application-oriented exploration is still at an early stage, which requires more joint efforts from scientists and engineers.…”

Two‐Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications

“…[97] Recently, 2D TaIrTe 4 -based vdW heterostructure has been studied in optoelectronics. [98][99][100] For DSM, the Dirac point can be formed by coinciding two Weyl points with opposite chiral positions in the same momentum space. Therefore, the Dirac point is quadruple degeneracy.…”

Impinge Weyl advantages on light

“…An established example is the shift current response can be enhanced by the Berry phase at the vicinity of Weyl nodes 10 , such effect is directly applicable for high-performance photodetection and energy harvesting 11 . In addition, photodetectors based on Weyl semimetals exhibits orbital photogalvanic effect, applicable for direct detection of the orbital angular momentum of light, a very changeling task otherwise 12 , 13 . As exhausted in the review, other nonlinear effects, such as anomalous current, second and high harmonic generation, inverse Faraday effect, are actively explored experimentally and one can envision their applications in nonlinear optoelectronics.…”