Photosensitive highly Er/Yb co-doped phosphosilicate optical fibers for continuous-wave single-frequency fiber laser applications

Journal of the Optical Society of America B: Optical Physics. 2020. Vol. 37. No. 10. P. 3077–3083.

Rybaltovsky A. A., Lipatov D. S., Lobanov A. S., Abramov A. N., Umnikov A. A., Bazakutsa A. P., Bobkov K. K., O. V. Butov

Highly Er/Yb co-doped phosphosilicate fibers with lowoptical losseswere fabricated by theMCVDmethod, utilizing an all-gas-phase deposition technique developed “in house.” Important characteristics such as photodarkening and photosensitivity of these fibers were thoroughly investigated. An almost negligible impact of photodarkeninginduced losses (no more than 1 dB/m) was discovered in the near-infrared spectral region. The photosensitivity of hydrogen-loaded fiber samples was studied using excimer laser irradiation at a wavelength of 193 nm. A photoinduced refractive index value of 110􀀀3 at the total UV irradiation exposure dose of 550 J=cm2 was achieved. A single-frequency laser with a Fabry–Perot short cavity was designed by inscribing highly reflective (R>99.9%) and partially reflective (RD94.3%) fiber Bragg gratings directly in the Er/Yb co-doped phosphosilicate fiber core. The laser showed stable CW output emitting with a narrow peak centered at 1551.5 nm in the absence of any signs of Yb3C parasite lasing in a wavelength range from1000 to 1100 nm.

Keywords: photosensitivity, fiber lasers