Simple Estimation of Fiber Dispersion and Laser Chirp Parameters Using the Downhill Simplex Fitting Algorithm

We report on a simple and fast method to estimate the fiber dispersion and laser chirp parameters on a dispersive Intensity Modulation and Direct Detection (IM/DD) optical channel. Based on the general IM/DD small-signal frequency response, we use the Downhill-Simplex algorithm to fit the channel measurement retrieved with a network analyzer to a general mathematical model. The method is proven to be quite efficient for light sources of different natures and with different adiabatic and transient chirp characteristics, including a Distributed Feedback (DFB) laser, an Electroabsorption modulator (EAM) and even a Reflective Semiconductor Optical Amplifier with fiber-Bragg grating (RSOA-FBG).