title: Highly efficient metallic optical incouplers for quantum well infrared photodetectors.
abstract: Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|(2) ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors.
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Long
authors.initials: L
authors.lastname: Liu
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Huang
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhan
authors.affiliation: School of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Zhenlin
authors.initials: Z
authors.lastname: Wang