Plasmonic-coupled quantum dot photodetectors for mid-infrared photonics

A plasmonic-coupled, InAs-based quantum dot photodetector fabricated for midwave infrared photonics is reported. The detector is designed to provide a broadband absorption [full width at half maximum (FWHM) greater than or similar to 2 mu m] peaked at similar to 5.5 mu m, corresponding to transitions from the ground state of the quantum dot to the quasi-continuum resonance state above the quantum well. From the coupling of this transition to the surface plasma wave (SPW) excited by an Au film atop the detector, fabricated with a 1.5 mu m-period, 2-dimensional array of square holes, a narrowband SPW enhancement peaked at 4.8 mu m with an FWHM less than 0.5 mu m is achieved. At similar to 90K, a peak responsivity enhanced similar to 5x by the plasmonic coupling is observed. Simulation reveals that this enhancement corresponds to collecting similar to 6% of the incident light; similar to 40% of the total absorption by the SPW excitation at the peak wavelength. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

A novel midwave infrared photodetector with plasmonic coupling for enhanced responsivity is reported. The detector features broadband absorption and narrowband SPW enhancement, making it suitable for detecting midwave infrared light.