Experimental and theoretical investigation of mode size effects on tilted facet reflectivity

Facet reflectivity from tilted devices has been investigated as a function of optical mode size. A theoretical approach is developed and completed by numerical simulation in order to calculate the effective facet reflectivity depending on optical mode size. The proposed approach is based on the plane wave expansion. Compared with other methods, the proposed one reveals clearly the physical insights, requires low computational effort and exhibits high reliability. We measured that 7° of mirror tilt introduces a reflectivity of 1.34 × 10^-2% for an optical mode size of 4.5 μm and a reflectivity of 6.25% for a mode size of 1.7 μm. We developed an analytical model that confirms those values.