Tuesday, February 11, 2020
The development of intense few-cycle mid-infrared (mid-IR, λ<5 µm) laser sources has made significant progress during the past decade, which has opened many opportunities for infrared nonlinear optics, high-harmonic generation and pump-probe experiments in the “molecular fingerprint” region. However, even longer carrier wavelengths (~10 µm) are needed in many applications. It is one of the current challenges facing ultrafast laser technology to generate high-energy, ultra-short long-wave IR (LWIR) pulses, beyond the capability of existing methods. To tackle this issue, we proposed and demonstrated a new scheme that utilizes asymmetric self-phase modulation (SPM) in a tailored plasma structure to generate multi-millijoule energy, single-cycle LWIR pulses tunable in a wide spectral range of 3-20 µm. Such a versatile ultra-short infrared sources opens up a new area of relativistic nonlinear optics of plasma and brings new opportunities for strong-field physics.