@article{oai:ynu.repo.nii.ac.jp:00010176,
 author = {Yoshioka, Katsumasa and Igarashi, Ippo and Yoshida, Shoji and Arashida, Yusuke and Katayama, Ikufumi and Takeda, Jun and Shigekawa, Hidemi},
 issue = {21},
 journal = {Optics Letter},
 month = {Nov},
 note = {We produce subcycle mid-infrared (MIR) pulses at a 4 MHz repetition rate via the optical rectification (OR) of sub-10 fs near-infrared pulses delivered by an optical parametric chirped pulse amplifier. The coherent MIR pulses generated in a GaSe crystal under an ultrabroadband phase-matching condition contain only 0.58–0.85 oscillation cycles within the full width at half-maximum of the intensity envelope. The use of OR enables excellent phase stability of 56 mrad over 5.6 h, which is confirmed by field-resolved detection using electro-optic sampling. An electromagnetic simulation using a finite integration technique reveals that the peak field strength can easily exceed 10 V/nm owing to the field enhancement resulting from focusing MIR pulses onto a tunnel junction.},
 pages = {5350--5353},
 title = {Subcycle mid-infrared coherent transients at 4  MHz repetition rate applicable to light-wave-driven scanning tunneling microscopy},
 volume = {44},
 year = {2019}
}