Protection of phosphate glass by BK7 glass film in ion-exchange processing

Surface corrosion of phosphate glass during ion-exchange processing for optical waveguide fabrication is studied, and a protection method by using BK7 glass film is proposed and demonstrated in this paper. The protection coating processing is described and optical microscope and atomic force microscope observations are presented. Characteristics of the planar waveguide were measured also to show the protection coating would not introduce influence to waveguide formation in the phosphate glass. Experimental results show that the method can serve an effective protection, and will improve the performance of rare-earth-doped active phosphate glass optical waveguides.