Signal processing for optical wavelength interleaver design

In this article, two application examples of signal processing for optical interleaver design are presented. The optical interleaver has become an important building block of the dense wavelength division multiplexing (DWDM) system. Numerous design diagrams have been proposed for the optical interleaver, and, among these diagrams, the Mach-Zehnder interferometer type interleaver and the Michelson interferometer type interleaver might be the most popular ones. The Mach-Zehnder interferometer is a special case of the finite impulse response (FIR) filter, and the Michelson interferometer belongs to the category of the infinite impulse response (IIR) filter. In this article, we demonstrate how signal processing techniques can be applied to design the Mach-Zehnder interferometer type interleaver and the Michelson interferometer type interleaver. Detailed Z-domain transfer functions of these two types of interferometers are presented. The two case studies presented in this article demonstrate how signal processing has become a great enabling technology for optical device design.