Design of a fiber-optic sensor with ultrahigh resolution for nitrogen dioxide detection based on gain-enhanced surface plasmon resonance

Abstract

Surface plasmon resonance in optical fibers can result in the creation of a highly sensitive device, compact and robust sensor. Nitrogen dioxide is one of the foremost greenhouse gases responsible for deteoriation of ecosystem and breathing disorder, it plays a direct role in global climate change. To date, all studies on surface plasmon resonance in optical fibers have relied on passive excitation. For the very first time, we propose a novel sensor architecture based on a gain enhancement of surface plasmons in optical fibers in this paper to detect nitrogen dioxide in the atmosphere. Hence, a pair of fiber gratings is embedded in the core, resulting in the formation of a cavity in which incident light with the Bragg wavelength is confined and simulated first in absence of NO2 environment and then by introducing NO2 concentration ranging from (10–100) ppm to accomplish our work, we observed change in reflectance peak varying in accordance with increasing concentration. Thus, the constructive interference between these waves results in optical field gain by a magnitude of 4. Our results indicate that a significant improvement in sensor performance is obtained on active surface plasmon excitation, anticipating to be of importance in high-precision applications.

Keywords

• Surface plasmon resonance
• Fiber bragg grating
• Gold thin films
• Finite element method
• Finite-difference time-domain simulation
• Eigenmode expansion method