Frequency selective Bragg filters based on (Mg,Zn) (S,Se)waveguides for the visible spectral range

Bragg grating transmission filters were fabricated on ZnMgSSe-ZnSSe-ZnMgSSe planar optical waveguide structures using a high resolution electron-beam lithographic process. Varying the grating geometry, the filter characteristics like resonance wavelength, modulation contrast, and stopband width can be adjusted. For example, for a L=600-μm-long grating with a period of Λ=120 nm, we achieve 16% residual transmission and a spectral width of 4 Å for the designed resonance wavelength of 603 mm. The experimental data can be explained quantitatively with a transfer matrix calculation assuming a coupling coefficient of 40 cm^-1