Figure 2: Three spatial modes supported by the channel waveguide structure given in Figure 1. The 2D boxes are 1.6 μm by 1.0 μm. These modes have significantly different confinement factors to the gain layer and therefore modal gain and significantly different waveguide loss due to the roughness of the side wall. The mode effective indices are 3.62, 3.43, and 3.17, respectively.