Generation of high-energy mid-infrared pulses via dual-chirped OPA

Abstract

In recent years, considerable effort has been made to develop high-energy infrared (IR) femtosecond laser sources owing to their advantages for applications in ultrafast and strong-field laser science. In this paper, we show our work on developing TW-class mid-infrared (MIR) femtosecond laser pulses in the 1–4 μm region using a dual-chirped optical parametric amplification (DC-OPA) method, which solved the energy scaling difficulties in standard OPAs. Using a sub-joule class Ti:sapphire laser as a pump for the DC-OPA system, MIR femtosecond pulses with 100-mJ-class energy and a flexible wavelength tunability are confirmed. Efficient energy scaling of DC-OPA is examined experimentally. Moreover, we find different features of DC-OPA from conventional OPA and narrow spectral bandwidth laser pumped optical parametric chirped pulse amplification (OPCPA). Temporal chirps in DC-OPA play critical roles in optimizing efficiency and spectral bandwidth. In addition, bandwidth narrowing of amplified pulses in DC-OPA can be minimized by optimizing the chirps of the seed and pump pulses. DC-OPA can be universally employed for energy scaling of near-IR, MIR, and far-IR pulses, regardless of the type of nonlinear crystal, and is helpful for efficiently generating few-cycle, carrier-envelope phase (CEP)-stable IR pulses with TW-class peak power.