Optical generation of microwave/millimeter-wave signals using two-section gain-coupled DFB lasers

We report the first analysis and experimental demonstration of tunable microwave/millimeter-wave signal generation in two-section gain-coupled distributed-feedback (DFB) lasers. Continuous tuning from 20 to 64 GHz was directly observed and characterized both in the electrical and optical domain. The mechanism of microwave generation in two-section gain-coupled DFB lasers is different from that of two-section index-coupled DFB lasers previously reported. As a result, gain coupling can lead to simultaneous large modulation indexes and high frequencies in two-section DFB lasers.