Enhancing Vernier Effect through Integrated Add-Drop Microresonator for High Sensitivity All-Optical Sensing

Abstract

The Vernier effect has recently sparked a lot of interest study in high sensitivity sensing due to its ability to suppress interstitial peaks and broaden the Free Spectral Range (FSR). An analytical simulation system was constructed to incorporate an add-drop Micro Ring Resonator (MRR) waveguide with partial reflecting air holes into the bus waveguide to acquire the interferometric resonance and generate the Vernier effect. The system was developed based on the scattering matrix method and the Optical Transfer Function (OTF). A comparison analysis has been conducted between Conventional Add-Drop (CAD) MRR and Interferometric Add-Drop (IAD) MRR configurations to measure the improved sensitivity. The spectrum was analyzed based on the FSR and the wavelength shift by the change of the refractive index. Both CAD and IAD-MRR have been optimized by varying the radii of the ring and the distance between the air holes in the bus waveguide. The optimized IAD configuration demonstrates a 166.11% enhancement in FSR value and yields higher sensitivity by 17.07% via the implementation of the reflecting holes in the bus waveguide. The IAD-MRR configuration also generated a higher Q factor value of more than four times than the CAD-MRR. These findings emphasize the potential of interferometric resonance in enhancing the Vernier effect thus achieving better performance of all-optical sensing applications.