Length dependence of cutoff wavelength for single‐mode fiber

Abstract

The effective cutoff wavelength of single‐mode fiber cable cannot be completely determined because the bending loss, which prevents propagation of the second‐order mode, depends upon the bending distribution of the fiber as well as on the length and index profile of the fiber. By measuring the bending loss of the LPn mode of step‐index single‐mode fiber, it is found that the effective cutoff wavelength of reel‐wound fiber shifts to lower wavelengths along the distance. The length dependence is proved by experiment and agrees well with the theory. The length dependence of the cutoff wavelength of optical cable is estimated by experiment and it is established that the effective cutoff wavelength can be prescribed by the microbending profile and, compared with the value given by the conventional bend method of a 2‐m sample, the decrease in effective cutoff wavelength for 1‐m cable is estimated as 0.1 um. If this length dependence is used, it can be applied in long‐distance systems provided a fiber having longer cutoff wavelength and favorable.bending loss characteristics or low dispersion is used.

Nonlinear fibre-optic devices pumped by semiconductor disk lasers

“…Secondly, it requires various intracavity elements, like fibre Bragg gratings, to be implemented and they should sustain considerable intracavity powers. Moreover, waveguiding properties of the fibre tend to deteriorate when operating considerably far from a cutoff wavelength [59]. Since the Raman conversion efficiency increases with increasing fibre length, the threshold of nonlinear effects, e.g.…”