LOSS INCREASE OF (LUNDBI)(3)(FEAL)(5)O-12 FILMS CAUSED BY SPUTTER ETCHING

Rib waveguides, which are made of magnetic garnet films of composition (LuNdBi)(3)(FeAl)(5)O-12 (LNB), fabricated by Ar sputter etching have large propagation loss in comparison with LNB slab waveguides. X-ray photoelectron spectroscopy (XPS) is used to investigate chemical state s of constituent elements existing in the surface layer where a Ti mas k has been deposited during the etching process. The analysis shows th at Fe chemical shift due to Ar+ ion bombardment can cause increase in the optical absorption loss, and hence the propagation loss. It is eff ective for suppressing the loss increase to employ a SiO2 mask deposit ed onto LNB film instead of a Ti mask.