Submicron Etched Beam Splitters Based on Total Internal Reflection in GaAs–AlGaAs Waveguides

Submicron etched beam splitters are designed, fabricated and characterized in Al
_0.9
Ga
_0.1
As-GaAs waveguides. Beam splitter transmission and reflection characteristics show clear dependence on gap dimension and angle of incidence. It is possible to obtain 8 to 30% power transmission by adjusting the gap dimension and angle of incidence. The experimental results agree well with three-dimensional (3-D) finite difference time domain (FDTD) simulations. The effect of imperfections, mainly the slope of etched sidewalls and variations in etch depth are investigated using 3-D FDTD. Design guidelines for low loss etched beam splitters are also given.