ABSTRACT
The net effect produces a response that looks like a simple product of the two individual transmittances. However, caution should be exercised not to allow the high-reflection zones of both filters to overlap, because that could result in high-transmission peaks appearing inside the reflection zones due to cavity resonances between the two high reflectors. This means that the starting long-pass and short-pass filters should have fairly wide-pass bands. The simplest type of bandpass filter is one that consists of two edge filters. It is possible to construct a long-pass filter and combine this with a short-pass filter such that the high-reflection band of the short-pass filter falls inside the high-transmission side of the long-pass filter. The reference wavelength of the long-pass filter has to be shorter than the reference wavelength of the short-pass filter.
