Accurate characterization of optical materials enables femtosecond LWIR pulses with terawatt-level peak power via bulk-material post-compression

Ultra-intense long-wave infrared (LWIR) laser systems offer exciting opportunities in accelerator physics, largely due to the quadratic scaling of the ponderomotive potential with laser wavelength. A critical factor in achieving femtosecond LWIR pulses with terawatt-level peak powers through bulk-material post-compression is understanding the intensity-dependent behavior of materials and their resistance to laser-induced damage under ultra-intense LWIR pulses. In this work, we demonstrate the post-compression of 2 ps, 9.2 µm laser pulses to 675 fs, achieving 1.6 TW peak power—a significant step toward the next generation of femtosecond LWIR lasers. This advancement was made possible through a systematic characterization of the nonlinear optical properties and laser damage thresholds of various LWIR materials under picosecond pulse durations. Based on these results, BaF2 and KCl were selected for the dispersive and self-phase modulation components, respectively, enabling a simple yet robust configuration. Combined with the ongoing development of a high-energy solid-state seed for the CO2 laser, this work demonstrates the feasibility of a high-power femtosecond LWIR source suitable for strong-field studies, including research in advanced materials and laser acceleration.