Loss analysis and interference effect in semiconductor integrated waveguide turning mirrors

Semiconductor integrated waveguide turning mirrors (IWTM) are investigated using the beam propagation method. A mirror is fabricated and modeled along with realistic geometries in the presence of offset and roughness of the mirror surface. An interference effect between waves reflected at different surfaces in the device is evidenced, that has strong impact on the device performance in the case of weakly-confining structures. A widely-accepted fabrication approach is criticized in view of this effect. A solution is outlined that minimizes the losses due to either technological limitations or interference.