A low-loss and compact waveguide Y-branch using refractive-index tapering

A new approach to an integrated Y-branch power splitter, useful for strongly guiding waveguide circuits, is proposed, fabricated and tested. The device uses adiabatic mode evolution by effective-refractive-index tapering to achieve a compact, low-loss geometry. Device performance is examined numerically by twoand three-dimensional beam propagation simulations. Y-branches with an overall length of /spl sim/330 μm and losses of <0.2 dB are then fabricated in GaAs-AlGaAs. A compact and low-loss 1×4 power splitter incorporating this Y-branch is also described and demonstrated.