Geometrical characterization of liquid core fibers by measurement of thermally induced mode cutoffs and interference.

Transmitted and scattered intensity in liquid core fibers have been measured as a function of temperature and v values of cutoff points obtained which are in good agreement with weakly guiding mode theory. We also report observation of oscillations in the transmitted intensity which we interpret to be caused by interference between modes. We show that measurement of the period of these oscillations can be used to make high-precision nondestructive measurements of core radius and core ellipticity along the fiber length.