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 two and three dimensional beam propagation simulations, Y-branches with an overall length of similar to 330 mu m and losses of < 0.2 dB are then fabricated in GaAs-AlGaAs. A compact and low-loss 1 x 4 power splitter incorporating this Y-branch is also described and demonstrated.