@article{oai:repo.qst.go.jp:00081709,
 author = {KANDA, NATSUKI and Ishii, Nobuhisa and ITATANI, JIRO and MATSUNAGA, RYUSUKE and Nobuhisa, Ishii},
 issue = {3},
 journal = {Optics Express},
 month = {Feb},
 note = {We report optical parametric amplification (OPA) of low-frequency infrared pulses in the intermediate region between terahertz (THz) frequency and mid-infrared (MIR), i.e., from 16.9 to 44.8 THz (6.7–17.8 μm). The 255-fs laser output of the Yb:KGW regenerative amplifier is compressed to 11-fs pulses using a multi-plate broadening scheme, which generates THz-to-MIR pulses with a spectrum extending to approximately 50 THz by intra-pulse differential frequency generation (DFG) in GaSe. The THz-to-MIR pulses are further amplified using a two-stage OPA
in GaSe. The temporal dynamics and photocarrier effects during OPA are characterized in the
time domain. Owing to the intra-pulse DFG, the long-term phase drift of the THz-to-MIR pulses
after two-stage OPA is as small as 16 mrad during a 6-h operation without any active feedback.
Our scheme using the intra-pulse DFG and post-amplification proposes a new route to intense
THz-to-MIR light sources with extreme phase stability.},
 pages = {3479--3489},
 title = {Optical parametric amplification of phase-stable terahertz-to-mid-infrared pulses studied in the time domain},
 volume = {29},
 year = {2021}
}