Design of a sensing glass fiber with specific refractive-index composition for a system with 1.3 μm wavelength light source

Abstract We propose a design of a sensing glass fiber for sensors that utilize optical power loss associated with bending of the fiber. First, we examine the optical power losses by simulation to determine the prototype design. Then three types of the fiber with different cutoff wavelengths are made. Each fiber exhibits a sensitive change in optical power near the bend radius R of 10 mm because of a leaky profile of the core-cladding. The fibers are designed for the combinatorial use of 1.3 μm wavelength light sources that are commonly employed in optical communications. The sensing system which utilizes the fiber developed has merits of low cost (compatibility with a light module and other optical components for 1.3 μm wavelength band), high sensitivity (leaky refractive-index composition for the fiber-optic sensor of the bend type), and long-term durability (suppression of glass-fiber static fatigue due to the relatively large bend radius (ca. 10 mm)).