- A thin film resonant cavity filter (TFF) is a Fabry-perot A cavity is formed by using multiple reflective dielectric thin film layers. The TFF works as bandpass filter, passing through specific wavelength and reflecting all other wavelengths. The cavity length decides the passing wavelength.
- Filter consisting two or more cavities dielectric reflectors is called thin film resonant multicavity filter (TFMF). 7.7.1 shows a three cavity thin film resonant dielectric thin film filter.
- For configuring a multiplexer and demultiplexer, a number of such filters can be Each filter passes a different wavelength and reflects other. While using as demultiplexer, the filter in cascade passes one wavelength and reflects all others onto second filter. The second filter passes another wavelength and reflects remaining wavelengths.
- A very flat top on passband and very sharp skirts are
- Device is extremely stable in temperature
- Very low loss.
- Device is insensitive to polarization of