10 Watt-Level High Energy CH4-Filled Hollow Core Fiber Picosecond Raman Laser at 2.8 μm

Here, we demonstrate a 10-watt-level high energy picosecond Raman laser in the 2.8 μm spectral region. This is realized in a 3.2-meter-long of CH₄-filled Nested hollow core anti-resonant fiber (HC-ARF) that is pumped by a 1064 nm solid-state picosecond pulse laser source with 50-watt-level output power. A gradient pressure of the methane gas in the HC-ARF creates an environment where the pump is gradually converted into Stokes signal, mitigating the thermal effects at the input end of the HC-ARF, which mediates high-power Stokes laser output. Picosecond pulses centered at 2807 nm wavelength with the maximum average power of 10.3 W (51.5 μJ) and peak power of >8.14 MW are generated, achieving a conversion slope efficiency as high as 25%. Additionally, the mid-infrared Raman laser source exhibits excellent beam quality of ${\mathrm{M}_{\mathrm{x}}}^2$ = 1.13 and ${\mathrm{M}_{\mathrm{y}}}^2$ = 1.13. To the best of our knowledge, this represents the highest-power gas-filled HCF picosecond Raman laser source in the 2.8 μm band. The technique presents a new pathway to build a MIR ultrafast Raman laser source with high-power, high-energy, and high-beam-quality. Such a flexible and high-performance laser source promises to be a powerful new tool for subsequent applications such as laser medicine, polymer material processing, and other fields.