Abstract

In this work, we demonstrated the double-cladding Tm/Al co-doped photonic crystal fiber (PCF) by laser additive manufacturing. The measurements show that the fiber was heavily doped with a Tm³⁺ concentration of 2.13% (mass fraction) without any crystallization. The splicing property of PCF was studied, and the integrity of the PCF air holes was maintained during the splicing process. The PCF with combiner pigtail has a splice loss of 0.23 dB. The all-fiber Tm/Al co-doped PCF amplifier system achieves a slope efficiency of 13% at 1948 nm with an output laser power of nearly 1.59 W. An upconversion process was also observed under laser excitation with a 1064 nm pulse. This method provides a new idea to deal with Tm-doped PCF fabrication and promotes the promising application of 2 µm fiber lasers.

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