Abstract: The expanding field of solid state laser and devices up- grade forms an interesting challenge for the development of coatings. A wide variety of diffrent specifications, often contradictory, has to be matched. The choice of deposition process and coating material is crucial with respect to losses, damage threshold, optical specifications and their long term stability.
Especially, up-grade LF-1l^# solid state laser has purposed a number of new re- quirements for optical coatings.We have developed a variety of optical coatings for up-grade LF-ll^# laser. Two parts divided discuss the multilayer coatingsin this paper. First part of this paper deals with the antireflection coatings of fused silica, BK7 glass a single wavelength, double wavelength and triple wavelength AR coatings. Coating design, deposition process and damage test are given.