ASE Power Determination in Erbium-Doped Fiber Amplifiers

The patent segments the total measured power into distinct components: signal power and ASE power. By separately determining the ASE power through a specific calculation method using amplifier parameters (gain, noise figure, bandwidth, inversion level) and subtracting it from the total measured power, the patent isolates the true signal power. This segmentation resolves the contradiction by enabling accurate power measurement despite the presence of ASE noise corruption.

The patent moves from using fixed tabulated noise figure values to a dynamic calculation approach where the noise figure is determined as a function of multiple varying parameters: amplifier gain, input power, optical bandwidth, and crucially, the inversion level of the erbium-doped fiber. This parameter-based approach adapts to different operating conditions including varying passive losses and channel configurations, thereby maintaining calculation simplicity while significantly improving ASE power calculation accuracy.

The patent adds the inversion level as a new dimensional parameter to the amplifier characterization, moving beyond the traditional two-parameter characterization (gain and input power). By incorporating inversion level—which directly reflects the actual state of the erbium-doped fiber and accounts for passive losses between stages—the patent creates a three-dimensional characterization model. This additional dimension enables accurate ASE power determination in multi-stage amplifiers while maintaining manageable complexity through systematic measurement and calculation procedures.