Analysis of optical-injected distributed feedback lasers using complex optical low-coherence reflectometry

A theoretical and experimental investigation of reflectograms obtained for a distributed feedback (DFB) semiconductor laser using a phase-controlled high-resolution optical low-coherence reflectometer was carried out, yielding the effective group refractive index and its variation above threshold, the cavity internal loss, as well as the grating coupling factor of a multiquantum-well DFB laser. In addition, direct measurements of the injection-induced complex-modal index changes are presented for the first time.