Opt Lett. 2019 Nov 1;44(21):5350-5353. doi: 10.1364/OL.44.005350.
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.
我们通过光学参量啁啾脉冲放大（OPCPA）产生的近红外亚 10 飞秒脉冲的光整流（OR），以 4MHz 的重复率产生亚周期中红外（MIR）脉冲。在 GaSe 晶体中，在超宽带相匹配条件下产生的相干 MIR 脉冲在强度包络的半最大值全宽内仅包含 0.58-0.85 个振荡周期。OR 的使用实现了 56mrad 的出色相位稳定性，持续 5.6 小时，这通过使用电光采样的现场分辨检测得到了证实。使用有限积分技术的电磁场模拟表明，由于将 MIR 脉冲聚焦到隧道结上会产生场增强，因此峰值场强很容易超过 10V/nm。
