主题：Ultrafast quantum-well mid-infrared photodetectors: time-resolved photocurrent by fs laser excitation at 10um wavelength

报告人：Prof. Stefano Barbieri 

时间：2026年9月17日 上午10:00

地点：中国科学院上海微系统所8号楼804会议室

报告简介

AlGaAs/GaAs multi-quantum-well mid-infrared (MIR) photodetectors (QWIPs) based on patch-antenna resonators have demonstrated response times on the ps timescale [1-3]. So far their frequency response has been obtained through heterodyne mixing of CW lasers. In this work we present for the first time their characterization under ~200fs-pulse excitation at 300K and 77K using a wavelength tunable MIR OPO. The so-generated photocurrent pulses are recorded in the time domain with a 67GHz sampling oscilloscope (4ps rise time). At high temperature we obtain ~8ps-long pulses independently of the incident power, setting an upper limit of ~4ps to the electron’s capture time in the quantum-wells.  At 77K, after an initially similar fast transient we observe the appearance of a ~40ps slow tail that we attribute to quantum-well recharging due to extra injection from the emitter contact. Using the well-known analytical model from Ershov et al. [4] we obtain a good agreement with the experimental data, yielding values of the photoconductive gain compatible with those obtained under CW illumination. 
[1] M. Hakl et al., ACS Photonics 8, 464–471 (2021). 
[2] Q. Lin et al. Optica 10, 1700 (2023)
[3] Q. Lin, et al. APL Photonis 10, 046102 (2025)
[4] M. Ershov et al. J. Appl. Phys. 8, 6442 (1999

报告人简介

Stefano Barbieri obtained his PhD in 2000 at Scuola Normale Superiore (Pisa, Italy). Since then, his research activity has been dedicated to the development and applications of optoelectronic devices based on intersubband transitions. In 2000 he joined the company Orbisphere SA (Geneva, Switzerland), where he developed a photoacoustic gas sensor based on mid-infrared (mid-IR) quantum cascade lasers (QCLs). In 2002 he joined Teraview Ltd. (Cambridge, UK) and the Cavendish laboratory of the University of Cambridge where he led an R&D activity focused on Terahertz (THz) QCLs. In 2006 he was recruited by CNRS (Centre National de la Recherche Scientifique) in France, where he is now Research Director. From 2005 to 2016 he was at the MPQ Laboratory of Paris Diderot University, where he investigated THz QCLs, focusing mainly on fast modulation, mode-locking operation and phase-locking to frequency combs. From 2016, he is part of the THz Photonics team at the IEMN Laboratory (Lille, France), where his research activity is mainly focused on ultrafast mid-IR detectors