Ultrafast 3.5 μm fiber laser

We report, to the best of our knowledge, the first mode-locked fiber laser to operate in the femtosecond regime well beyond 3 mu m. The laser uses dual-wavelength pumping and nonlinear polarization rotation to produce 3.5 mu m wavelength pulses with minimum duration of 580 fs at a repetition rate of 68 MHz. The pulse energy is 3.2 nJ, corresponding to a peak power of 5.5 kW. (C) 2021 Optical Society of America

Automated summary

This is the first mode-locked fiber laser to operate in the femtosecond regime well beyond 3 micrometers, generating 3.5 micrometer wavelength pulses with a minimum duration of 580 femtoseconds, pulse energy of 3.2 nanojoules, and peak power of 5.5 kilowatts.