Abstract

The ability of realization of polarization-insensitive devices is an important issue in widely spreading high-speed optical communication systems. In this respect, although optical switches/modulators in the form of intersecting waveguides were shown to be small-size, low-loss, fast and integrable devices, their polarization characteristics are yet to be investigated. Fig 1 shows such a switch/modulator where an exponentially curved electrode is used in activation of the electro-optic material [1]. When the signal V(t) is applied to the electrode, the optical input appears at the reflection port and the process is, in general, polarization dependent. In case of a guided mode which can be taken as the superposition of differently oriented plane waves, it is impossible to make all of them to undertake total reflections. Some components with angles of incidence larger than the critical one, are transmitted for which the polarization dependency can not be avoided. If, instead, an exponentially curved electrode is introduced where the angle of incidence of all plane wave components are equalized [2], total reflection of all components can be achieved where no polarization sensitivity is realized Fig 2 shows the difference of reflectivities of perpendicular polarizations for the curved and straight electrodes. As seen, the difference vanishes for the case of a curved electrode while it is appreciable in a straight one. To summarize, an exponentially curved electrode is effective in suppression of the polarization dependency of intersecting waveguide type optical switches/modulators.

© 2000 IEEE