Structural design of triangular core–shell nanowires for sensing polarized mid-infrared light

Manipulating and detecting polarization states of light plays an important role in developing technology in various fields, such as remote sensing, medical phototherapy, and quantum information. However, polarization control in mid-infrared (mid-IR) wavelengths, especially longer than 10 µm, is obstructed by the limitation of material properties. Searching for materials and designing structures that respond to polarized light in this spectral range is still challenging. In this work, triangular core–shell AlGaAs/GaAs nanowires are numerically studied using the finite difference method. The effects of the core shift and rotating angle on the absorption coefficients are concentrated. Highly anisotropic absorption of polarized light in the mid-IR range is found when the core shifts upward and downward. Our results show that this anisotropic property is influenced by the symmetries of electron quantum states confined in the system. Broadband absorption wavelengths from 9.7 to 17.5 µm are unexpectedly found in the structure with appropriate system size. Our finding indicates that triangular core–shell nanowires are a potential platform for next-generation photonic devices capable of manipulating polarized light in a wide range of mid-IR wavelengths.