ИСТИНА

Microwave systems, cellular networks and other various personal communications systems require devices that are capable of receiving, converting and processing signals in the millimeter and centimeter wave ranges. A broad palette of devices was developed recently for transferring radio frequency and microwave signals directly to optics. This presents all advantages of optical communication channels, allowing to transmit data securely with high rates, low loss, low power consumption. Electro-optic modulators based on interaction of optical and microwave waves in high-Q nonlinear optical resonators with whispering gallery modes provide a promising platform of that kind. In our work we present analysis of electro-optic interaction of a fundamental whispering gallery optical mode in a dielectric microdisc and a radio frequency mode of a half-wave microstrip line placed on the disc circumference. 2D and 3D numerical models of the system are developed. Both optical and radio frequency modes are simulated using finite element method with Comsol Multiphysics software. The comparison between the models is presented, and a theory of modulation in the multi-mode system is discussed. The magnitude of electro-optic effect is calculated depending on optical and radio frequency mode numbers. The cases of different polarizations of signal and pump optical field for standing and travelling waves are also considered. It is shown that the modulation in the system exists only for particular sets of mode numbers determined by selection rules. The magnitude of the effect in such system is shown to have an extremal dependence on the microstrip length for a given set of mode numbers.