Design and analysis of an optical miroring resonator as NaCl and Hb Sensor

Over the past few years, optical engineering has made significant advancements and has been successful in a number of crucial fields, including sensors. Microring-resonator (MRR)-based sensors have garnered the most interest, as they are so compact and sensitive in comparison to other sensors. Researchers from all around the world are utilizing MRR-based sensors in various application sectors. In this thesis, a Lithium-niobate-on-insulator (LNOI) based optical microring resonator has been designed for biomedical application. Although Silicon-on-insulator platform is widely used for designing compact microring resonators. LNOI is chosen over the silicon-on-insulator (SOI) technology due to its feasibility in tuning the sensing parameters. Furthermore, Lithium Niobate has some special properties including mechanical, piezoelectrical, ferro electrical, electro-optic, photoelastic, thermo-optic and non-linear optical properties and it is easy to tune. The designed microring resonator consists with a radius of 5-μm ring waveguide. The cross section of the ring is composed of four layers including sensing layer, lithium niobate layer, buffer layer and substrate layer. The gap between the linear waveguide and ring waveguide is assigned as 250nm. After designing the sensor COMSOL as Radio Frequency (RF) solver is utilized to find out the fundamental mode. In the next stage, OptiFDTD software is used for implementing the two-dimensional simulations based on finite-difference time domain method. Experimental result shows that the designed microring resonator of 10−4 Refractive Index Unit (RIU) and sensitivity of 57.86 nm/RIU. Finally, this work evaluated the performance of the sensor for sodium chloride (NaCl) and haemoglobin (Hb) sensing.

• Supervision