Static, dynamic, and noise analysis of multisection DFB lasers using frequency-domain transmission line model

A novel frequency-domain transmission line model for multisection distributed feedback (DFB) lasers is developed. The characteristic impedances of active periodic structures are derived. A multisection DFB laser is described as a transmission line network, with each section represented by a transmission lint segment with a corresponding characteristic impedance. Static, dynamic, and noise analysis of multisection DFB lasers is demonstrated. The reflections at the junctions between sections are evaluated more accurately. The resonant condition of the equivalent transmission line network, instead of cumbersome Wronskian, is used to reformulate the rate equations. The diffusion coefficient of Langevin noise terms of any two different positions is solved for the first time, resulting in a more accurate noise analysis of multisection semiconductor lasers. Analytical expressions of the dynamic responses and noise properties of multisection DFB semiconductor lasers are derived.