Deposition of Optical Coatings by Molecular Beam Techniques and Their Characterisation

Abstract

Significant improvements can be made in the fabrication of optical thin film structures by using molecular beam and ultrahigh vacuum techniques. These lead to the achievement of more stable films and multilayer coatings, with improved morphology, density and resistance to laser induced damage. The microstructure of the film can be controlled to a high degree by using quasi-superlattice techniques, which also provide a means of refractive index synthesis. This can be applied to simple graded structures or to complex periodic gradings as required for Bragg-like structures. Etalon filters fabricated using the technique have been used for optical bistability experiments and have exhibited stable operation for periods of many hours, under continuous cycling.