The specification of DWDM filter becomes higher with the development of WDM technology. The filter must have sharp slope, low insertion loss, qualified pass band width, stop band width and temperature stability. Suitable substrate and coating material should be selected firstly. And multi- cavity F-P filter was adopted to design the narrow band pass filter.
This paper discusses the overall design of the weak signals detection filters, gives a design example of weak signals detection filters in the visible light range, its coating technique and the experiment result applying for weak signals detection.
This paper proposes a new method by utilizing the ultrathin metallic film that has a property of n k to design narrowband high reflectors, derives a few of formulae about its spectral reflection properties and gives examples of the design.