Lasing characteristics of Er³⁺-doped silica fibers from 1553 up to 1603 nm

The laser oscillations from 1553 up to 1603 nm have been demonstrated in Er³⁺-doped silica fibers with a doping rate of 2500 ppm. Wide changes in laser oscillation wavelengths are due to broad splitting of the upper sublevels in the ⁴I_{15/ 2} manifold, caused by the random structure of the silica matrix. It has been shown that unpumped parts of the Er³⁺ ions in the end pumped fiber laser configuration play an important role in the wavelength changes of the laser oscillation. For an absorbed pump power of 320 mW at 514 nm, output power of 0.5 mW was obtained at 1603 nm.