BPM design optimization and experimental improvement of a Ti:LiNbO/sub 3/ ridge waveguide linear-mode confinement modulator

A theoretical device model for a ridge waveguide mode confinement modulator on z-cut LiNbO/sub 3/, based on the beam propagation method (BPM), is used for design improvement purposes. Following this design technique, a fabricated device yielded a much improved performance of 97% modulation depth with a drive voltage of only +or-8 V, in good agreement with the design calculations. The improvement in the experimental performance of this modulator is mainly due to a reduced buffer layer thickness and an optimization of the ridge height. A theoretical analysis based on an accurate effective-index model combined with the BPM is used to predict the performance of the device.<>