Resonant fluorescence line narrowing and gain spectral hole burning in erbium-doped fiber amplifier

Gain spectral hole burning and resonant fluorescence line narrowing have been performed at low temperature in standard aluminosilicate erbium-doped fiber amplifier to demonstrate the nature of the line broadening. Comparison of the hole-width measurements with resonant fluorescent line narrowing data shows a good agreement at 77 K, working temperature for which both experiments are feasible and have been performed simultaneously. The FWHM results reported here compare well with the earlier line profile measurements performed on aluminosilicate glass preform of the same chemical composition as the fiber. The pump power dependences are reported and indicate that they influence both the depth and line width, which may induce a limitation for wavelength division multiplexing techniques in the long-haul transmission regime of telecommunications.