Theory of Optical Leaky-Wave Antenna Integrated in a Ring Resonator for Radiation Control

TL;DR

This paper presents an analytical model and design of an integrated leaky-wave antenna within a ring resonator, enabling precise radiation control and modulation using CMOS-compatible silicon waveguides.

Contribution

It introduces a novel analytical framework for the integrated device and demonstrates a CMOS-compatible design for electronically tunable radiation control.

Findings

High-quality factor enhances radiation control via resonance tuning.

Efficient radiation achieved even with short leaky-wave segments.

Carrier injection in silicon effectively modulates far-field radiation.

Abstract

The integration of a leaky-wave antenna with a ring resonator is presented using analytical guided wave models. The device consists of a ring resonator fed by a directional coupler, where the ring resonator path includes a leaky-wave antenna segment. The resonator integration provides two main advantages: the high-quality factor ensures effective control of radiation intensity by controlling the resonance conditions and the efficient radiation from a leaky-wave antenna even when its length is much smaller than the propagation length of the leaky wave. We devise an analytical model of the guided wave propagation along a directional coupler and the ring resonator path including the antenna and non-radiating segments. The trade-offs regarding the quality factor of resonance and the antenna efficiency of such a design is reported in terms of the coupler parameters, leaky-wave constant and radiation length. Finally a CMOS-compatible OLWA design suitable for the ring resonator integration is designed where Silicon is utilized as the waveguide material for a possible electronic control of radiation intensity. The simulation results together with the analytical model show that slight variations in the leaky-wave's propagation constant, realized through excitation of excess carriers in Si domain, is sufficient to control the far-field radiation modulation with high extinction ratio.