Broadband THz absorption spectrometer based on excitonic nonlinear optical effects  

作　　者：Avan Majeed Pavlo Ivanov Benjamin Stevens Edmund Clarke Iain Butler David Childs Osamu Kojima Richard Hogg 

机构地区：[1]Department of Electronic and Electrical Engineering,University of Sheffield,Sheffield S14DE,UK [2]School of Engineering,University of Glasgow,Glasgow G128LT,UK [3]EPSRC National Centre for Ⅲ-Ⅴ Technologies,University of Sheffield,Broad Lane,Sheffield S37HQ,UK [4]Department of Electrical and Electronic Engineering,Graduate School of Engineering,Kobe University,1-1 Rokkodai,Nada,Kobe 657-8501,Japan

出　　处：《Light(Science & Applications)》2019年第1期922-926,共5页光（科学与应用)（英文版）

摘　　要：A broadly tunable THz source is realized via difference frequency generation,in which an enhancement to χ^((3)) that is obtained via resonant excitation of III–V semiconductor quantum well excitons is utilized.The symmetry of the quantum wells(QWs)is broken by utilizing the built-in electric-field across a p-i-n junction to produce effectiveχ(2)processes,which are derived from the high χ^((3)).This χ^((2)) media exhibits an onset of nonlinear processes at~4Wcm−2,thereby enabling area(and,hence,power)scaling of the THz emitter.Phase matching is realized laterally through normal incidence excitation.Using two collimated 130mW continuous wave(CW)semiconductor lasers with ~1-mm beam diameters,we realize monochromatic THz emission that is tunable from 0.75 to 3 THz and demonstrate the possibility that this may span 0.2-6 THz with linewidths of ~20 GHz and efficiencies of ~1×10^(-5),thereby realizing ~800 nW of THz power.Then,transmission spectroscopy of atmospheric features is demonstrated,thereby opening the way for compact,low-cost,swept-wavelength THz spectroscopy.

关 键 词：TUNABLE thereby nonlinear 

分 类 号：TN2[电子电信—物理电子学]