External light-concentrating structures designed for fluorescent antennas based on refractive index modulation.

Abstract

Fluorescent antennas (FAs) exhibit considerable promise in optical wireless communication (OWC), primarily due to their advantages over conventional optical systems in terms of optical gain and field of view (FoV). This paper presents a COMSOL-based model designed to optimize external light-concentrating structures for FAs, with its accuracy validated through both qualitative and quantitative comparisons. Leveraging refractive index modulation and the conservation of optical étendue, two distinct light-concentrating structures are developed. The first structure couples the FA with an array of optical fibers, achieving up to a 1.5-fold increase in optical power density at the emitting surface. The second structure integrates the FA with a Compound Parabolic Concentrator (CPC), incorporating media of varying refractive indices. When refractive index matching is achieved with commonly used silicon-based detectors, this structure theoretically enhances optical power density by approximately 2.5 times. Compared to prior designs aimed at improving FA performance, the external light-concentrating structures proposed here improve the system's SNR without significantly affecting other device performance metrics.