DIRECT MEASUREMENT OF PROPAGATION CONSTANT IN OPTICAL WAVE-GUIDES BY HETERODYNE SCATTERING DETECTION (HSD) METHOD

A new measurement method for the propagation constant of optical waveg uides, which can measure the phase difference of two distant points no ndestructively, was proposed and demonstrated. A super-fine fiber prob e for the photon STM is used to pick up the scattered light from an op tical waveguide, and the collected light is detected using a heterodyn e technique. The phase difference between two points is measured from the phase change of the electrical signal of heterodyne detection as t he fiber probe traces the waveguide pattern. The phase difference betw een 100 mu m distant points in a three-dimensional ARROW was successfu lly measured and the error was evaluated to be 0.25% by comparison wit h the theoretical value.