Spectral Stability in Double Pass Erbium Doped Fiber ASE Source

The spectral and power stability of a single pass Erbium Doped Fiber Source (EDFS) were experimentally studied, in order to evaluate the limits of such device as broad band optical sources. The experimental setup is made of a double pass forward EDFS, with erbium doped fiber, pumped by a 1480 nm laser, with the output radiation coupled into an Optical Spectrum Analyzer (OSA). The spectra were obtained for different pump powers and fiber temperatures. The spectra were used to calculate the mean wavelength and the effective bandwidths which are plotted against the variable parameters. Numerical derivatives give the rates of change of mean wavelength and effective bandwidth with the parameters of interest. With the temperature fixed at 25 ºC we obtained a minimum mean wavelength to input power rate of about 7.5 ppm/mW for a pump power of about 270 mW and a maximum effective bandwidth of 28.2 nm for a pump power of about 200 mW. With the pump power fixed at 130 mW we observed a mean wavelength to temperature rate increasing monotonically from 12 to 68 ppm/ºC in the range between 20 ºC and 60 ºC and a maximum effective bandwidth of 27.7 nm at 20 ºC.