Develop attosecond light and metrology probing nanoworld

Ming-Chang Chen^1,2*

¹Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Ming-Chang Chen, email:mingchang@mx.nthu.edu.tw

Many physical and chemical processes which define our daily life take place on atomic scales in space and time. Capturing the most fundamental dynamics in matters requires short wavelengths for nanometer resolution and short pulse with a duration of femtoseconds (fs /10^-15 s) or attoseconds (as /10^-18 s). Challenges arise from the generation of bright coherent short EUV and the development of time-resolved metrology in the attosecond time domain. In this talk, I will first present our new post-compression invention to present how NTHU generates intense single-cycle pulses (0.98 mJ, 3.2 fs at 885 nm). Such single-cycle pulses can produce bright, isolated attosecond pulses straightforwardly. Later, I will introduce new nonlinear spectroscopy, called high-harmonic ellipsometry, using the polarization degree of freedom to quantify precisely the complex dipole response of the high-harmonic generation process [1]. The precision measurements that are able to quantitatively extract the absolute dipole response information—in both amplitude and phase—are essential to elucidate the quantum dynamics of the HHG process. The resulting high harmonics contain information about the electronic and geometric arrangement (or redistribution after the driving laser) of the radiating molecules or solids. This novel nonlinear ellipsometry opens up new prospects for insight into strong field dynamics of fundamental processes associated with energy and angular momentum transfer between electron/spin systems and the symmetry-dependent properties of molecules and materials, further advancing attosecond science.

[1] K.-Y., Huang, L.-C., Asaga, K., Tsai, M.-S., Rego, L., Huang, P.-C., et al. High-order nonlinear dipole response characterized by extreme ultraviolet ellipsometry. Optica, 8(4), 484–492 (2021).

Keywords: nonlinear optics, high harmonic generation