A novel technique for finely controlled near-infrared beam transmission of titania

The paper discusses a novel method of controlling near-infrared beam transmissions through a silica–titania dual layer. It was found that a KrF excimer laser was able to change the transmission characteristics of the dual layer coatings over a wide range from 0.1 to 12 dB at a small step of less than 1 dB for the transmission at both 850 and 1550 nm. The controlled beam transmission was attributed to the controllable laser-effected darkening of the titania layer. The developed method can be applied for the manufacture of adjustable filters widely used for optical communication systems. # 2003 Elsevier B.V. All rights reserved.