LOW-LOSS THIN-FILM LINBO3 OPTICAL WAVE-GUIDE SPUTTERED ONTO A SIO2/SI SUBSTRATE

We report what is to our knowledge the first successful attempt in prism coupling a laser beam into a lithium niobate optical waveguide grown on a thermally oxidized (100) Si substrate by magnetron rf sputtering. Bragg x-ray diffraction, Rutherford backscattering, and birefringence measurements confirm that the sputtered films were nearly stoichiometric as well as highly textured lithium niobate. The refractive indices were n(TE) = 2.199 +/- 0.002 and n(TM) = 2.263 +/- 0.002. The lowest propagation loss in the waveguide was determined to be 1.9 +/- 0.1 dB/cm at a wavelength of 633 nm.