Er~(3+)-Yb~(3+) co-doped phosphate glass optical fiber for application at 1.54 microns

摘要

We present current work developed at INO on phosphate glass optical fiber for laser and amplifier applications at 1.54 microns. Core and cladding glasses were fabricated by a multi-components melting process which gave an uniform refractive index core profile. Rod-in-tube method under Argon atmosphere was used to fabricate optical fibers. The effect of nitrogen atmosphere on hydroxyl groups OH~- during glass melting was studied. The absorption coefficient calculated at 3.42 μm was found to be lower than 0.5 cm~(-1) which corresponds to less than 70 ppm OH~-. Absorption and emission cross sections were calculated at 1534 nm. Fabrication process allowed us to decrease background losses of core Er~(3+)- Yb~(3+) co-doped fiber between 0.02 and 0.04 dB/cm. Laser power was measured at 1563 nm and a 26% slope efficiency was achieved with a 22 cm-long single-clad fiber co-doped with 1.1 wt% in Er~(3+) and 11.1 wt% in Yb~(3+). For the same fiber, an internal gain was found to be 20 dB at 1536 nm for a 5-cm-long fiber.