Determination of the refractive indices of layers in a multilayer stack by a guided-wave technique.

The m-lines technique is used to measure the refractive indices and thicknesses of layers embedded in a multilayer stack. The multilayer considered is deposited by ion plating. Its formula is silica-H-L-H-L-H-air, where H and L denote Ta(2)O(5) and SiO(2)lambda/4 layers, respectively, with lambda = 514.5 nm. Measurements indicate that the refractive index of Ta(2)O(5) is 5 x 10(-3) greater when the layer is close to air than when the layer is inside the coating and that the Ta(2)O(5) is slightly more birefringent.