The Adoption of Chalcogenide Glass Fiber as Pulse Stretcher in an All-Fiber Structured 2 μm Chirped Pulse Amplification System

We present the development of an As
₂
S
₃
fiber-based reusable inline optical connector; and, for the first time to the best of our knowledge, integrated it into a 2 μm chirped pulse amplification system as the pulse stretcher. By this mechanism, a near 20 times pulse stretching ratio was achieved in 0.5 m-long this As
₂
S
₃
fiber and the introduction of insertion loss as low as 2.84 dB while it was connected with silica fiber. After the follow-up fiber amplification and self-compression mechanism, the laser average output power was boosted to 1.97 W and pulse duration was optimized to 2.53 ps. Moreover, to further inspect the laser pulse property, the pulses were then delivered into a 5.3 m-long ZrF
₄
-BaF
₂
-LaF
₃
-AlF
₃
-NaF (ZBLAN) fiber which was fusion spliced to SM1950 fiber. Thanks to the 0.4-dB low fusion splice loss between these fibers, a 1.56-W supercontinuum source with bandwidth of 1.93-3.50 μm is obtained. The measured two hours of root-mean-square value of power fluctuation of this laser source is 0.13%, indicating an ultra-high long-term power stability. This work will lay a solid foundation in the realization of the all-fiber structured high-power thulium-doped fiber amplifier with high compactness.