Characterization of Nonlinear Distortion in Intensity Modulation and Direct Detection Systems

Intensity modulation and direct detection (IM-DD) systems are widely used in short-reach optical networks. Thus, developing a practical accurate method to characterize nonlinear distortion estimate system performance is essential, as this the foundation of IM-DD design. The amount can be characterized using noise-to-power ratio (NPR). Although measuring NPR notch requires only spectrum analyzer, cannot applied with non-Gaussian stimuli general. We employ directly modulated distributed feedback (DM-DFB) laser-based systems. Nonlinear these attributed two specific mechanisms: imperfect power–current characteristic DM-DFB laser interaction among modulation, chromatic dispersion (CD), detection. Experimental results demonstrated that accurately mean absolute error 0.47 dB, even when pulse amplitude modulation. subjected nonlinearity could estimated by equivalent additive noise model. Besides, also effective Mach–Zehnder modulator-based has nonnegligible CD. However, it failed case negligible Considering not always effective, we analyzed attributes various found above applicable dominated second-order nonlinearity.