Hundred-meter-scale, Kilowatt Peak-Power, Near-Diffraction-limited, Mid-Infrared Pulse Delivery Via the Low-Loss Hollow-Core Fiber.

We report a high-power single-mode mid-infrared (MIR) pulse delivery system via anti-resonant hollow-core fiber (HCF) with a record delivery distance of 108 m. Near -diffraction-limited MIR light was transmitted by HCFs at wavelengths of 3.12-3.58 mu m using a tunable optical para-metric oscillator (OPO) as the light source. The HCFs were purged beforehand with argon in order to remove or reduce loss due to parasitic gas absorption (HCl, CO2, etc.). The minimum fiber loss values were 0.05 and 0.24 dB/m at 3.4-3.6 mu m and 4.5-4.6 mu m, respectively, with the 4.5-4.6 mu m loss fig-ure representing, to the best of our knowledge, a new low loss record for a HCF in this spectral region. At a coupling effi-ciency of similar to 70%, average powers of 592 mW and 133 mW were delivered through 5 m and 108 m of HCF, respec-tively. Assuming the 120-ps duration of the MIR pulses remained constant over the low-dispersion HCF (theoreti-cal maximum: 0.4 ps/nm/km), the corresponding calculated peak powers were 4.9 kW and 1.1 kW.