EDFA Wavelength Dependent Gain Spectrum Measurement Using Weak Optical Probe Sampling

Wavelength dependent gain is a critical parameter in erbium-doped fiber amplifiers and is the primary determinant of the channel power divergence and excursions in optical transmission systems, each of which varies with channel loading in wavelength-division-multiplexed (WDM) systems. In an optical transmission system, measurements of the wavelength dependent gain between two locations can be used to obtain estimates of optical power excursions that occur in optical circuit switching. Non-intrusive sampling of just 10% of the WDM channel positions using weak probe signals achieves less than 0.15 dB error for the gain spectrum estimation of the amplifier with 5 dB tilt. In a two-span node-to-node network with a 3 dB peak-to-peak channel power difference, the weak probe approach further shows to provide less than 0.2 dB error in optical channel power excursion prediction for changes in channel loading.