Wavelength multiplexing system based on ring resonators

Abstract

Wavelength Division Multiplexing, WDM, is a technology developed for applications in telecommunications with the purpose of combining numerous wavelength signals into one single fibre. The aim of this research is the characterization of WDM systems of ring resonators with planar optical waveguides. The optical responses for different configurations, dimensions, and materials are analysed by doing a parametric study both considering analytical expressions and a Finite Element Tool. The results are from add-drop topologies with one, two and three rings. The main difference between topologies with the same parameters is the number of resonance wavelengths, which is higher due to the increase in the number of ring-shaped waveguides. It is concluded that adjusting the rings’ dimensions, the resonant wavelengths are tuned. Furthermore, the higher the rings’ radius the lower is the free spectral range, that can take values from 40 nm to 90 nm. Then, the number of resonant peaks in a wavelength range may change. Also, 1500–5000 describes the values computed for the quality factor, whereas the full width at half maximum varies within some units of nanometres. For models with different core materials, the higher transmittances decrease with lower core refractive indexes and the resonance width increases. These are new degrees of freedom to tune the response of the device that can definitely work as optical wavelength multiplexer, having losses from 20% to 40% considering the transmitted optical power.

Keywords

• Coupled mode theory
• Finite element methods
• Optics
• Ring resonator
• WDM