PERFORMANCE COMPARISON OF GAIN-COUPLED AND INDEX-COUPLED DFB SEMICONDUCTOR-LASERS

Comprehensive numerical simulations with the transmission-line laser m odel (TLLM) are used to compare the behavior of gain-coupled DFB laser s with index-coupled DFB lasers fabricated from identical materials. T hese simulations compare slope efficiency, threshold current, spectra, small-signal modulation bandwidth, maximum-intrinsic modulation bandw idth, large-signal transient response and chirp, relative-intensity-no ise (RIN) spectra, and feedback sensitivity for coherence collapse. In most cases gain-coupled lasers with additional index coupling have be tter performance than index-coupled lasers for a given material. Howev er, high-coupling factor index-coupled lasers do have lower threshold currents, lower RIN levels, and lower sensitivity to external feedback than gain-coupled lasers, although spatial hole burning in these devi ces can be disadvantageous.