High Energy Ultrafast Laser at 2 μm Using Dispersion Engineered Thulium-Doped Fiber

Abstract

We report on demonstration of high energy pulse laser at 2 μm by employing a normal dispersion fiber attained by a waveguide dispersion engineering. The normal dispersion fiber has a W-type refractive index profile, with a Thulium(Tm)-doped core. In contrast to a strong anomalous dispersion at 2 μm in a step-index fiber, the design allows strong waveguide dispersion that can generate normal dispersion at the Tm emission band. Mode area scalability of this fiber is discussed under the normal dispersion requirement. The Tm-doped fiber (TDF) is deployed in a ring cavity to produce mode-locked pulses near 2 μm. Subsequently, the pulse is amplified with more than 27 dB gain through the normal dispersion TDF. The output pulse energy reaches up to ∼525 nJ at 1852 nm without pulse breaking due to the engineered dispersion. The achieved pulse energy is record high for all-fiber configuration near 2 μm, to our knowledge.

All-fiber ultrafast amplifier at 1.9 μm based on thulium-doped normal dispersion fiber and LMA fiber compressor

“…Then pulses are compressed in fibers with anomalous GVD to achieve low duration and high peak power characteristics. However, very few fiber laser systems based on thulium-doped normal dispersion fibers have been experimentally embodied 18 , 19 . These setups feature durations of more than 600 fs, which are less promising for coherent supercontinuum generation.…”

All-fiber ultrafast amplifier at 1.9 μm based on thulium-doped normal dispersion fiber and LMA fiber compressor

“…Then pulses are compressed in fibers with anomalous GVD to achieve low duration and high peak power characteristics. However, very few fiber laser systems based on thulium-doped normal dispersion fibers have been experimentally embodied 13,14 . These setups feature durations of more than 600 fs, that are less promising for the coherent supercontinuum generation.…”