A novel technique for measurement of the mode indexes of channel waveguides

An accurate technique for measurement of small differences in the mode indexes of channel waveguides is presented and compared with the prism coupler. It has a distinct advantage over the prism coupler method since it allows measurements in buried waveguides as well. The absolute mode index of an individual guide can also be obtained provided a guide near the mode cutoff is available on the same substrate. The technique is expected to be useful with waveguides of high index materials, especially when the prism coupler monitoring the uniformity of optical fibers or measuring the waveguide birefringence.>