Investigation of Lossy Mode Resonance Phenomenon in High Index Cladding Optical Fiber

Here, we report the novelty of inducing the lossy mode resonance (LMR) phenomena without usage of any additional coating onto the fiber device. Instead, a high refractive index cladding (HIC) optical fiber is utilized, eliminating the need for additional coatings. This kind of optical fiber has a cladding whose refractive index is higher than the core. The outer cladding with high refractive index permits the generation of lossy modes, a key component of the LMR phenomenon. The diameter of the fiber is modified through chemical etching. This modification serves as a tuning mechanism for the LMR phenomenon, influencing the number of modes guided, order of mode, and resonant wavelength of LMR bands. The developed device is noted for its simplicity and cost-effectiveness. The sensor exhibits a maximum sensitivity of 1700 nm/RIU to surrounding refractive index (SRI) around region of water refractive index. The higher sensitivity and simplification of the device make it suitable for applications in biological and chemical sensing.