LOW-LOSS ELECTRODE DESIGNS FOR HIGH-SPEED OPTICAL MODULATORS

摘要

An optical modulator device that substantially prevents coupling of a desired coplanar waveguide (CPW) electromagnetic wave mode with other spurious modes within non-active sections the modulator structure without significantly impacting the modulation efficiency in an active section of the device. The modulator includes an electrooptic substrate and a buffer layer that is formed on a surface of the electrooptic substrate. The buffer layer includes a thin portion that occupies an active section of the electrooptic substrate where modulation occurs, and a thicker portion that overlies the electrooptic substrate in one or more non-active sections of the device. The thinner portion of the buffer layer allows significant electrical-optical overlap of the CPW electromagnetic wave with an optical wave propagating within a waveguide formed in the active section of the device substrate. One or more thicker buffer layer portions on one or more non-active sections of the electrooptic substrate substantially prevent penetration of the CPW electromagnetic field into the electrooptic substrate in the non-active sections, and thus restrict coupling with undesirable modes the electrooptic substrate can support.