Analysis of High Q Resonant Tunnelling-based Filter Using a Legendre Polynomial Expansion Method

optical filters based on photonic resonant tunnelling effect are discussed. This kind of filter shows steep-edge, low insertion loss amplitude response and linear phase response suitable for WDM and DWDM applications. Two kinds of filters, namely discrete level and continuous profile filters are introduced. The filters are analyzed using a novel method based on Legendre polynomial expansion of electromagnetic fields, thus avoiding numerical problems peculiar to most conventional analysis methods. The method not only helps avoiding the numerical instability, but also can be used for analyzing the whole structure of the continuous profile filters in one stroke, eliminating the need for cumbersome multilayer analysis.

Keywords:

Legendre Polynomials , Resonant Tunnelling , DWDM filters