Spectral range of operation of coupledhyphen;mode optical filters

摘要

The spectral range of operation of optical coupledhyphen;mode filters (CMF) is investigated. The CMF principle is based upon the stresshyphen;induced energy transfer between orthogonal polarized optical modes, which occurs in birefringent materials at the isotropic wavelength where phasehyphen;matching is ensured. A nonexhaustive list of birefringent materials which exhibit an isotropic wavelength is drawn up. The whole visible spectral range is covered continuously by using mixed gradedhyphen;bandhyphen;gap hexagonal crystals such as CdShyphen;CdSe and ZnShyphen;CdS. This range is extended up to 2.1 mgr;m by using piezobirefringent cubic compounds. Materials with other crystalline structures enable the extension of this spectral range down to 1200 Aring;. The optical activity of chalcopyritehyphen;structure semiconductors can advantageously replace stresshyphen;induced mode coupling.