Modal Gain Analysis of Transverse Bragg Resonance Waveguide Lasers With and Without Transverse Defects

We use a transfer matrix method to analyze the modal gain of transverse Bragg resonance (TBR) structures. We show that these TBR structures can support two types of modes characterized by different modal angles: small mode angle (SMA) modes and TBR modes. We discuss the origin, modal properties and field distributions of both the TBR modes and SMA modes. Three different feedback mechanisms are proposed to select the desired TBR modes.