| Popis: |
The theory, design and preparation of narrow-band spectral filters operating in reflection will be described. Such filters consist of multilayers containing both dielectric and metallic films and are of particular interest for applications in fibre-optical communication systems in the wavelength region from 1250-1600 nm. In the theoretical discussion relationships will be developed which relate the potential transmittances of the main metallic film to important parameters of the filter, namely bandwidth and rejection; and it will be shown how the materials of the layers are chosen to meet these and other requirements such as free spectral range. Practical considerations, including the monitoring procedure, will be discussed; and the results of photometric observations on five filters will be presented and compared with theoretical predictions. |
