Optical-Field-Controlled Photoemission from Plasmonic Nanoparticles with state-of-the-art Ti:sapphire Oscillators
1生醫光電所, 陽明大學, 台北市, Taiwan
* Presenter:SHIH-HSUAN CHIA, email:shchia@ym.edu.tw
Strong-field light-matter interactions driven by few-cycle visible to near-infrared light pulses enable the study of matter’s electronic response with sub-optical-cycle, i.e. attosecond, precision. Strong-field interactions with solids typically require field strengths >1 GV/m; such fields are typically achieved by focusing high energy (μJ- to mJ-level) CEP-locked amplifier systems. In recent years, it has been shown that with plasmonic nanoantennas, one can locally enhance the optical field strength and reduce the required optical pulse energy for achieving strong-field light-matter interactions by two to three orders of magnitude. Thereby, strong-field interactions can be driven by nJ-level laser pulses from unamplified, mode-locked oscillators at MHz-level repetition rates. On the other hand, generation of nJ-level octave-spanning pulses still requires careful design and precise manipulation of nonlinear optics and laser physics. I will discuss the development of state-of-the-art octave-spanning Ti:sapphire oscillators, and it has been applied for the investigation of CEP-sensitive photoemission from an array of plasmonic nanoantennas. Current studies are underway to determine optimal conditions for high SNR CEP detection using the nanoantennas by tuning pulse compression, beam spot size, and the central wavelength of the nanoantennas’ plasmonic resonance. And the result shows that at least an order of magnitude improvement in CEP-sensitive current is within reach comparing with the use of Ti:saphhire lasers and other fiber-based laser systems. The further possibility of source improvement will be discussed, and such high-energy CEP-locked laser design enables the development of novel lightwave/PHz electronic technologies and fundamental investigations of strong-field light-matter interactions throughout the visible to near-IR spectrum.

Keywords: femtosecond optics , Strong field physics, Laser technology