Macro-Bending Loss of Single-Mode Fiber Beyond Its Operating Wavelength

A standard telecommunication-grade single-mode optical fiber is designed to have a low macro-bending loss in its entire operating wavelengths to comply with the ITU-T Recommendation G.652. In this paper, we described the potential use of such a fiber as an intensity-based sensor due to the macro-bending loss as an alternative to using a bending-sensitive fiber. We calculated the macro-bending loss of several single-mode optical fiber patchcords using the classical Marcuse equation at several wavelengths, and measured its transmission loss due to bending using an optical spectrum analyzer. For each type of fibers there is a wavelength with a significant macro-bending loss of the LP11 mode when the V-number of the fiber lies between 2.4 and 4, and that of the LP01 mode when the V-number of the fiber lies between 1 and 2.4. This work shows a thorough mathematical and experimental analysis for the posibility in using standard telecommunication fibers for intensity based-fiber sensor taking the benefit of bending loss phenomenon using commercial light sources

Simulation of Birefringence and Polarization Mode Dispersion Characteristics in Various Commercial Single Mode Fibers

Single mode optical fiber operation for long haul distance communication media has rapidly developed. Several efforts are implemented to reduce and control the attenuation and absorption of signal propagation. However, fiber parameters still experienced interference with internal and external factors that result birefringence and polarization mode dispersion such as bending power losses, signal widening and increasing wavelengths. In order to reduce and optimize the interference which is experimentally difficult to demonstrate because of the very long fibers hence a numerical simulation is set with perspective of twisted fiber disorder as a function of wavelengths and fiber geometry. The simulation evaluates the various refractive indices, radius of fibers and wavelength sources. The quality of optical fiber interference can be identified from the twisted power losses values with different variations of twisted radius. This model obtained indicates the greatest power losses occurring as a function of radius, refractive indices and wavelength. The results show that normalized frequency value has important role in determining the effectiveness the optical fiber performance and stability of power deliver. The addition of wavelength can affect the fibers experiencing birefringence and polarization mode dispersion occurring at wavelength of telecommunication regimes

Optical Fiber Sensor Experimental Research Based on the Theory of Bending Loss Applied to Monitoring Differential Settlement at the Earth-Rock Junction

Considering the differential settlement in the junction between the structure perpendicular to the dike and the body and foundation of dike (called the earth-rock junction in this paper) during runtime, an experimental investigation of optical fiber sensor monitoring was conducted. Based on the sensing mechanism of single-mode optical fiber bending loss, the experiment focused on the influence of the bending radius of an optical fiber on the bending loss. In view of the characteristics of the differential settlement in the earth-rock junction, we designed a butterfly-type optical fiber sensor and composite optical fiber sensor for monitoring device in monitoring the differential settlement to enlarge the monitoring range and improve the sensibility of optical fiber sensor. Based on the research on the working principle and bending properties of the composite optical fiber monitoring device, we conducted experiments on the bending of the composite optical fiber sensor monitoring device and the use of the device for monitoring the differential settlement. These experiments verified the feasibility of the composite optical fiber sensor monitoring device at monitoring the differential settlement in the earth-rock junction