Spectral gain hole-burning at 1.53 μm in erbium-doped fiberamplifiers

Spectral gain hole-burning at λ₀=1.53 μm was observed in an erbium-doped fiber amplifier at temperatures between 4.2 and 77 K. The hole width was found to broaden with temperature for T ⩾20 K according to a T^1.73 law. From the data, the room-temperature homogeneous linewidth associated with the 1.531-μm transition in the ⁴I_13/2-⁴I_15/2 laser system was determined to be Δλ_h=11.5 nm for aluminosilicate fibers