Optical loss stability of a fiber cable under lateral force and optimum design of the coated fiber structure.
Optical loss increase characteristics under lateral force were investigated to determine the load limit for coated fiber. Plastic deformation of the coating was analyzed, and the loss increase was found to occur in the large deformation region beyond a limit theoretically determined using structural dimensions (diameter and thickness) and the material constant of the coating. The optimum coating structure for preventing loss increase has been designed by introducing the result of the lateral deformation limit as well as fiber stress induced by the lateral force and fiber strain at low temperature. The nylon outer and silicone layer diameters are 0.9 and 0.4 mm, respectively.
Optical coupling between coated fibers in a compact fiber ribbon
Optical coupling between coated optical fibers in a fiber ribbon for use in compact and high-density optical cable is described. By means of a measurement system having a sensitivity of -70 dB. optical coupling of -40 dB due to a small radius fiber bend is measured for an actual fiber ribbon coated with UV-curable resin. The optical coupling mechanism is discussed using analysis models of a coated optical fiber bend. Theoretical analyses and experimental results confirm that optical coupling occurs only when the refractive indices of coating materials satisfy the condition of radiating light traveling from a fiber core to a ribbon coat.
Measurement and Demonstration of Thermal Expansion Coefficient
There are many classroom demonstrations, such as the ball-and-ring experiment, for showing the existence of thermal expansion of solids. The coefficient of linear expansion α (= increase in length divided by the original length times the change in temperature) may be measured in high school laboratories using a number of methods.1–4 In this paper we describe an especially simple experiment for determining α for a metal rod. It is based on the well-known optical lever method and is suitable for either a laboratory experiment or a classroom exercise.