Design of low-loss tapered waveguides using the telescope structure compensation

A low-loss tapered waveguide is achieved by telescope structure compensation. The configuration of this design is similar to the Galilean telescope based on bulk geometrical optics. We numerically calculate the transmission efficiency in the use of the beam propagation method (BPM) and the finite-difference time-domain method. The BPM simulation results reveal that the normalized transmission efficiency is more than 95%, even if the tapered angle is as large as 10/spl deg/.