High-power nanosecond pulse amplified spontaneous emission source at 3.1 μm based on C2H2-filled nested hollow core anti-resonant fiber

We report a 3.1 μm high-power amplified spontaneous emission (ASE) source in nanosecond pulse regime based on a 10-m-long acetylene-filled nested hollow core anti-resonant fiber (HC-ARF). By pumping with a homemade 1.5 μm high-power repetition-rate-tunable nanosecond pulse single-frequency fiber laser, a maximum output power of 15 W ASE pulse light has been achieved with a repetition rate of 5 MHz, a pulse width of 58 ns, a pulse energy of 3μJ, and a peak power of 51.7 W. To the best of our knowledge, it is the highest output power for such gas-filled HC-ARF nanosecond pulse ASE sources in 3 ∼ 4 µm mid-infrared (Mid-IR) region. In addition, we characterize the pulse width evolution at the pump laser’s repetition rate of 1 MHz, 3 MHz, and 5 MHz. When the 1.5 μm pump laser operates at a repetition rate of 1 MHz and a pulse width of 70 ns, the 3.1 μm ASE’s narrowest pulse width of 11 ns is realized, which is owing to the gain saturation effect occurs during the Mid-IR pulse amplification. This research demonstrates the capability of hollow core fiber gas lasers for high-power Mid-IR pulse generation and provides new opportunities for efficient pulse narrowing.