All‐fiber laser generating at 3.8 μm pumped by 1565 nm fiber laser and the second‐order laser at 1.9 μm

We propose an all‐fiber source at 3.8 μm with a high Tm‐doped fiber as the gain medium pumped by a 1565‐nm high‐power fiber laser. With a laser diode at 1565 nm amplified by a high power erbium‐doped fiber amplifier injecting into a segment of Tm‐doped fiber, a fiber laser at 3.8 μm generates. Simultaneously, a second‐order laser at 1.9 μm (dual‐frequency of 3.8 μm) can be observed clearly. The laser has a threshold pump power of ∼300 mW and generates more than 176 mW continuous‐wave output power with 1560 mW pump power. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:848–850, 2014