Generation of high-repetition rate sub-cycle mid-infrared pulses applicable to lightwave-driven STM
Yokohama National University, Jun Takeda
Lightwave-driven scanning tunneling microscopy (STM) has been realized using carrier-envelope-phase (CEP)-stable THz pulses, and electron tunneling was coherently manipulated across a tunnel junction. Although THz-field-driven STM enables ultrafast dynamics to be probed and even controlled with atomic spatial resolution1,2), the time resolution is limited to the sub-picosecond timescale. The use of CEP-stable mid-infrared (MIR) pulses will significantly improve the time resolution, and will enable the filming of various ultrafast quantum processes that are unattainable with THz pulses.
In the present study, we could successfully produce high-repetition rate sub-cycle MIR pulses with a pulse duration of 31 fs and a peak electric field of 190 kV/cm via optical rectification (OR) of sub-10 fs near-infrared pulses delivered by an optical parametric chirp pulse amplifier (8.2 fs pulse duration, 850 nm center wavelength, and 4.3 W average power). The use of OR enables excellent phase stability of 56 mrad over 5.6 h. This achievement will open the door to strong-field physics as well as ultrafast nanoscale electronics and metrology with an unprecedented signal-to-noise ratio.
Reference: K. Yoshioka I. Igarashi, S. Yoshida, Y. Arashida, I. Katayama, J. Takeda, and H. Shigekawa, Opt. Lett.44, 5350-5353 (2019). (doi.org/10.1364/OL.44.005350)
1）K. Yoshioka et al., Nat. Photon. 10, 762 (2016).
2）K. Yoshioka et al., Nano Lett. 18, 5198 (2018).