Analysis and characterization of Er-Yb codoped-depressed inner cladding fiber

摘要

A 125 μm-diameter erbium-ytterbium-codoped single-mode fiber is reported. The utilization of depressed inner cladding guarantees the improvement of trade-off between the effective area and bending sensitivity compared to step-index profiles. Changes of cutoff wavelength, effective area, and macrobend loss under the influence of various structural parameters, and the balancing selection of core radius and subsidence layer width are investigated systematically. For the laboratory-made depressed inner cladding fiber, a macrobend loss of 0.06 dB/loop for a bending radius as tight as 10 mm was achieved, while maintaining an effective area of 164.22 μm~2 with intact single-mode properties at 1550 nm. The maximum small signal gain was achieved at 40.9 dB, and the gain fluctuation was less than 1 dB at the C-band. The fiber is suitable for high-power, small, portable, and handy optical fiber devices.