LARGE-SIGNAL SPURIOUS-FREE DYNAMIC-RANGE DUE TO STATIC AND DYNAMIC CLIPPING IN DIRECT AND EXTERNAL MODULATION SYSTEMS

Large-signal spurious-free dynamic range (SFDR) is useful in an optica l system with a high intensity noise level, which can be due to optica l reflections or optical beat interference, and with large modulating signals to achieve sufficient carrier-to-noise ratio (CNR). A closed-f orm analysis on large-signal SFDR due to static and dynamic clipping f or direct and external modulation systems is presented in this paper. The analysis can be applied to laser diodes (LD's) and external modula tors with arbitrary transfer functions. We have used the analysis to p redict the theoretical upper-bound for large-signal SFDR due to static clipping in an ideal LD add external modulators with various lineariz ation techniques. We have also used the analysis to predict the dynami c-clipping-induced nonlinear distortions (NLD's) id. a weakly clipped LD, and confirm that dynamic clipping is more important to consider th an static clipping when weak LD clipping takes place. Large-signal SFD R's in practical LD's and external modulators were also compared. The validity of our analysis is confirmed through computer simulation and actual measurement of clipping-induced NLD's in a typical CATV-quality DFB LD.