Designing DWDM filters? (or Multiple-Cavity Filters for other purposes)

The DWDM Assistant takes the pain and tedium out of the process for the design of multiple-cavity filters, particularly those intended for Dense Wavelength Division Multiplexing. The DWDM Assistant takes a desired specification and produces a set of candidate designs using the method of symmetrical periods.

The figure above shows the performance of a filter design produced by the DWDM Assistant with an added two-layer non-quarterwave matching structure. The figure below shows a magnified view of the passband.

The properties of the candidate designs are displayed and sorted in a number of user-specified ways, such as total layer thickness, deposition time, and ripple performance. The symmetrical period technique used by the DWDM Assistant is enhanced by a ripple optimization algorithm that adds structures composed only of quarterwave layers to reduce the ripple in the passband. In general, a number of designs will satisfy the given requirements for a filter, but the DWDM Assistant makes it possible to examine thoroughly and rank candidate designs according to critical criteria.