Dimensionality-enhanced mid-infrared light vortex detection based on multilayer graphene

Abstract

Recent conceptual demonstrations of direct photocurrent readout of light vortexes have enabled the development of light orbital angular momentum (OAM)-sensitive focal plane arrays and on-chip integration of OAM detection. However, known OAM-sensitive materials are limited to two topological Weyl Semimetals (TMS) belonging to the C_2v point group, namely, WTe₂ and TaIrTe₄. Both are fragile under ambient conditions, and challenging for large scale epitaxial growth. In this work, we demonstrate that multilayer graphene (MLG), which is CMOS compatible and epitaxially growable at the wafer scale, is applicable for OAM detection in the mid-IR region. Using an MLG photodetector with a designed U-shaped electrode geometry, we demonstrate that the topological charge of OAM can be detected directly through the orbital photogalvanic effect (OPGE) and that the OAM recognition capability of MLG is an order of magnitude greater than that of TaIrTe₄. We found that the detection capability of MLG is enabled by the enhanced OPGE response due to the reduced dimensionality and scattering rate. Our work opens new technical route to improve OAM recognition capability and is immediately applicable for large-scale integration of ambient stable, mid-infrared direct OAM photodetection devices.