Abstract
Optical waveguides with losses <1 dB/cm at 632.8 nm have been prepared by sputtering tantalum in O2–N2 mixtures. As the fraction of N2 in the sputtering atmosphere increases, the refractive index of the guides exhibit a sharp maximum and then decreases to a much lower value, and the films become birefringent. Using an oxygen discharge, the indices at 632.8 nm for both TE and TM modes are 2.083 ± 0.003, but the values are 1.850 and 1.877, respectively, for the highest fraction of nitrogen used. The indices have been measured at wavelengths down to 457.9 nm. For low fractions of N2, the results are consistent with a decreasing film density and a constant molecular polarizability, but a number of effects, including the birefringence, are inconsistent with this picture. Waveguide structures, such as interconnects, branching waveguides, and layered directional couplers, have been demonstrated using films with different indices. The birefringence has also been verified by observation of interference between TE and TM modes simultaneously coupled into the guide.
© 1975 Optical Society of America
Full Article | PDF ArticleMore Like This
S. J. Ingrey and W. D. Westwood
Appl. Opt. 15(3) 607-609 (1976)
Mario Kobayashi and Hiroshi Terui
Appl. Opt. 22(19) 3121-3127 (1983)
Rabi Rabady and Ivan Avrutsky
Appl. Opt. 44(3) 378-383 (2005)