For sensing applications in the molecular fingerprint region there has been an ever increasing demand for compact and efficient, spectrally versatile laser sources. Many solutions to this source problem have been neither compact nor efficient, and over the past few years increasing interest has been directed towards rare-earth-doped fluoride lasers to meet these exacting demands. For operation in the 2.6–3.4 µm spectral range, Dysprosium-doped fluoride systems have been reported with sub-watt output powers and efficiency up to 18% in fiber-bulk component configurations. This current work, however, takes the Dy-doped fluoride laser to another level, with average output power exceeding 10 W and an optical pump to output laser efficiency of 58%, in a completely fiber-integrated format.

To form the cavity, the 5.5 m long, commercially available, single-mode, Dy-zirconium fluoride fiber employed had fiber Bragg gratings directly written into it, through the fiber’s polymer coating, using femtosecond laser inscription. Pumping was in-band, by a fiber-coupled, laser-diode-pumped, Er-fluoride fiber laser, operating at 2.83 µm, providing up to 25 W, of which up to 19 W was coupled to the laser via a 1 m length of undoped fluoride fiber. At the highest output powers, a 0.4% RMS stability was achieved, with a detector resolution limited linewidth of less than 70 pm. The authors infer that increased efficiency should be possible through active fiber length optimization, but note that further power-scaling, although possible, would be more difficult and would need significant reduction in the cavity losses and improvements in the fused splice technology employed. However, this work as it stands represents a major milestone in developments in compact, efficient, high-power mid-infrared sources.

---

---

 Add Comment

You must log in to add comments.