Dielectric resonator antenna–coupled T2SL cascades for LWIR enhancement

Abstract Type-II InAs/InAsSb superlattice (T2SL) interband cascade infrared photodetectors (ICIPs) are promising candidates for high-operating-temperature long-wavelength infrared (LWIR) detection owing to their mature epitaxial growth and flexible band-structure engineering. ICIP architectures alleviate the trade-off between optical absorption and carrier collection efficiency, while GaAs immersion lenses further enhance optical coupling. However, new challenges arise as pixel sizes scale down. In the subwavelength regime, optical confinement within the absorber becomes increasingly difficult, resulting in reduced absorption efficiency. In this work, dielectric resonator antenna structures are investigated using rigorous coupled-wave analysis to enhance optical field confinement under subwavelength conditions. The simulation results indicate that for a detector width of 1 μm, the absorption in the target wavelength range of 9–9.5 μm is enhanced from 5.76% to 10.18%, leading to a responsivity increase from 0.051 to 0.09 A W −1 . This approach provides a promising strategy for improving optical absorption in LWIR T2SL photodetectors.