Rate equation analysis of slow-light photonic crystal lasers

Slow-light (SL) in active photonic crystal (PhC) waveguides enhances the modal gain per unit length [1], with application to shorter lasers [2]. Recently, we have proposed a coupled-Bloch-mode (CBM) approach [4] to analyze active PhC structures. Essentially, the presence of material gain in a line-defect waveguide is viewed as a weak perturbation to a reference structure with purely real refractive index. In the SL regime, the optical gain induces a distributed feedback (DFB) between the counterpropagating Bloch modes of the reference waveguide. The active waveguide is efficiently described by a scattering matrix [5], which accounts for the SL gain enhancement and gain-induced DFB. In particular, this effect reveals that SL semiconductor optical amplifiers may benefit from a smaller linewidth enhancement factor (LEF) [5], as they would experience a weaker backscattering.