title: Mid-infrared-pumped quantum cascade structure for high-sensitive terahertz detection.
abstract: Based on multiple quantum wells, we design a pumping-detection quantum cascade structure for the detection of terahertz (THz) radiation. In the structure, carriers are first pumped by a mid-infrared (MIR) laser to an excited state, to get enough energy space for the following fast longitudinal optical (LO) phonon extraction. Within the LO-phonon extraction stair, an absorption well is designed for THz detection. Due to the establishment of LO-phonon stair extractor, carriers transport between quantum wells in picosecond range and a high responsivity for THz absorption can be obtained. We also find that doping in both MIR active well and extractor region is significant for high-speed response of the THz detection. Our design is expected to extend the high-sensitive detection of a quantum cascade photodetector from middle wave of MIR to THz region.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xie
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Suqing
authors.initials: S
authors.lastname: Duan
authors.forename: Weidong
authors.initials: W
authors.lastname: Chu