Spectral Dependent Propagation of Low Order Modes in Bend and Temperature Stressed Single Mode Fibers

The cutoff wavelength of higher order modes in single mode fibers is a function of the physical characteristic of a fiber and physical manipulation of the fiber through bending and temperature change. A mathematical model has been developed to describe spectral dependent propagation of the LP11 mode through single mode fibers as a function of altered physical construction, bend radius, fiber pinch and temperature. The field solution was derived via a third-order extension of the WKBJ (Wentzel, Kramers, Brillouis, and Jefferies) method in order to more closely describe the propagation constants of the higher order modes in the center dip graded index single mode fiber. The results of an experimental analysis of single mode fibers have verified the basis of this model. An all dielectric temperature sensor was constructed that observed only spectral shifts. Calibration of the sensor is based only on spectral standards, not on intensity