3 μm Watt-Level All-Fiber Lasers Based on Mid-IR Dielectric-Coated Fiber Mirrors

report watt-level mid-IR Dy3+- and Er3+-doped all-fiber lasers using highly resistant dielectric-coated fiber mir -rors. The fiber pigtail mirror is specifically designed for dichroic operation (i.e. anti-reflection at 970-1200 nm pump wavelength and high-reflection around 3 mu m laser wavelength), and shows a high damage density of > 5 MW/cm(2), which is favorable to high-power mid-IR laser operation. The Ta2O5 monolayer protective film coated on ZBLAN fiber end-facet was used to mitigate the fiber tip photodegradation. Both of the compact all-fiber mid-IR cavities are formed by efficiently connecting the Dy3+- and Er3+-doped ZBLAN gain fibers with dielectric-coated fiber mirrors using the standard FC/PC fiber adaptor, respectively. An Er3+: ZBLAN all-fiber laser at -2.80 mu m is achieved with a 5.697 W maximum output power anda slope efficiency of 32.4%. Moreover, we realize a -2.93 mu m Dy3+: ZBLAN all-fiber laser with the maximum output power of 1.148 W anda slope efficiency of 18%, which is the highest output power of 1.1 mu m-pumped Dy3+: ZBLAN fiber laser. This work may offer a promising way to the low-cost, miniaturized, high-power mid-infrared all-fiber laser.

Automated summary

This report presents the use of highly resistant dielectric-coated fiber mirrors in watt-level mid-IR Dy3+- and Er3+-doped all-fiber lasers. The specially designed fiber pigtail mirror allows for efficient dichroic operation and exhibits high damage density, making it suitable for high-power mid-IR laser operation. A Ta2O5 monolayer protective film is used to mitigate fiber tip photodegradation. The compact all-fiber mid-IR cavities are formed by connecting the Dy3+- and Er3+-doped ZBLAN gain fibers with dielectric-coated fiber mirrors. The achieved maximum output powers and slope efficiencies are reported for both Dy3+ and Er3+ lasers.