半导体直接泵浦钛宝石超快激光振荡器驱动的自旋太赫兹发射光谱系统(特邀)  

Spintronic Terahertz Emission Spectroscopy System Driven by Direct Diode Pumped Ti∶Sapphire Ultrafast Oscillator(Invited)

作　　者：杜琳[1] 李培炎 黄滋宇 杨明 吴晓君 Du Lin;Li Peiyan;Huang Ziyu;Yang Ming;Wu Xiaojun(School of Electronic and Information Engineering,Beihang University,Beijing 100191,China;VIULASE GmbH,Vienna 1230,Austria)

机构地区：[1]北京航空航天大学电子信息工程学院,北京100191 [2]VIULASE GmbH,奥地利维也纳1230

出　　处：《光学学报》2024年第17期346-356,共11页Acta Optica Sinica

基　　金：国家自然科学基金区域创新发展联合基金(U23A6002);国家自然科学基金重大研究计划项目(92250307)。

摘　　要：率先采用半导体直接泵浦的小型化钛宝石飞秒激光振荡器驱动太赫兹(THz)光谱系统,并在无外磁场条件下实现反铁磁|铁磁|重金属(IrMn_(3)|Co_(20)Fe_(60)B_(20)|W)异质结中THz信号的高效产生。通过研究样品方位角、入射面、外加面内磁场、泵浦功率以及泵浦激光光斑中心位置对THz信号发射性能的影响,验证其自旋THz辐射机理,并发现该异质结不是在聚焦透镜焦点处产生THz信号的效率最高,而是在焦点前的辐射信号更强。这项工作不仅验证了半导体直接泵浦的小型化、低成本钛宝石激光振荡器是直接应用于自旋THz发射光谱系统的首选,还率先发现无外磁场驱动的IrMn_(3)|Co_(20)Fe_(60)B_(20)|W异质结在超短激光脉冲泵浦下的异常行为,为进一步推动钛宝石飞秒激光器驱动的小型化超宽带THz时域光谱成像技术应用提供了数据支撑。Objective The spintronic terahertz(THz)emitters developed in recent years have shown numerous advantages such as ultrabroadband,low cost,easy integration,and tunable polarization.As a result,they are increasingly demonstrating significant practical value in THz technology applications.However,advancing the development of THz time-domain spectroscopy(THz-TDS)systems crucially depends on combining high-efficiency,broadband spintronic THz emitters with low-cost,miniaturized titanium sapphire(Ti∶sapphire)laser oscillators.In our study,we use a miniaturized direct diode-pumped Ti∶sapphire ultrafast oscillator to drive the THz spectroscopy system,achieving efficient THz emission from antiferromagnetic|ferromagnetic|heavy metal(IrMn_(3)|Co_(20)Fe_(60)B_(20)|W)heterostructures under no external magnetic field conditions.We not only verify the spintronic THz radiation mechanism but also find that the heterostructure has a stronger radiation signal before the focusing lens focus.These experiments demonstrate that miniaturized,low-cost direct diode pumped Ti∶sapphire ultrafast oscillators are the preferred choice for direct application in spintronic THz emission spectroscopy systems,which is a powerful tool for analyzing the interactions between femtosecond lasers and different materials.This research lays the foundation for further promoting the application of miniaturized ultrabroadband THz time-domain spectral imaging technology driven by femtosecond lasers.Methods We utilize a direct diode pumped Ti∶sapphire ultrafast oscillator to drive the THz time-domain spectroscopy system.This laser adopts a new direct diode pumping scheme,combining the advantages of traditional Ti∶sapphire lasers and fiber femtosecond lasers,and features high performances with small size and low cost.It can provide laser pulses with a center wavelength of 800 nm,pulse duration of 47 fs,repetition rate of 80 MHz,and output power of 625 mW.The laser output beam is divided into three paths:the first excites a photoconductive antenna to gene

关 键 词：超快光学 半导体直接泵浦钛宝石激光器 自旋THz发射 THz时域光谱技术 反铁磁|铁磁|重金属异质结 

分 类 号：O436[机械工程—光学工程]