IEC TR 61292-1 pdf download Optical amplifiers – Part 1: Parameters of amplifier components
5.1 .12 active fibre dopant distribution concentration of dopant rare-earth ions in the fibre as a function of the fibre radial coordinate
5.1 .13 pumping efficiency for a given active fibre, the slope of the gain versus pump optical power curve under specified operating conditions
5.1 .14 saturation pump power for a given active fibre, the pump optical power level above which the small-signal gain shows no further increase
5.1 .15 threshold pump power the minimum pump optical power necessary to reach a small-signal gain equal to 1 in a given active fibre when the fibre length is short enough so that the pump optical power remains constant along the fibre
5.1 .16 active fibre operating temperature temperature to be maintained for normal operating condition, given in the relevant detail specification
NOTE Amplification characteristics of active fibre strongly depend on its temperature. Thus, EDF in the many EDFA unit is maintained with the certain constant temperature. Many EDFA units include heater device or TEC in order to control active fibre temperature. Fibre operating temperatures of 40 ˚C ~ 70 ˚C are usually specified as operating temperature. Some of fixed gain EDFAs (especially smaller packaged EDFA), do not include this feature. 5.2 Pump laser A pump laser is used to provide excitation energy for active fibre. By introducing the strong pumping light from a pump laser to active fibre, the signal light will be amplified by stimulated emission from a rare-earth ion such as Er 3+ in EDF.
5.2.1 pumping wavelength nominal wavelength of the emission spectrum of the pump laser. In EDFA, 980 nm and 1 480 nm are commonly used for pumping wavelength
5.2.2 pumping scheme set-up of the EDFA characterized by the direction of pump optical power propagation with respect to signal direction NOTE Usually, three schemes are used: co-propagating, where the pump and the signal propagate through the active fibre in the same direction; counter-propagating, where the signal and the pump propagate through the active fibre in opposite directions; bi-directional, where two pumps propagate simultaneously through the active fibre in both directions.
Regarding pumping schemes other than pump direction, a polarization combining scheme and a wavelength combining scheme are considered for detailed design to enlarge pump power. However, a single laser diode pump scheme is described as a classic example in this technical report.
5.2.3 pumping power optical power associated with the pump, injected into the active fibre
5.2.4 centre wavelength pump efficiency of EDF depends on the overlap integral of EDF absorption spectrum and pump LD spectrum, so the centre wavelength of pump laser is crucial for EDF pumping