Wavelength demulti/multiplexers with non-sinusoidal filtering characteristics composed of point-symmetrically connected Mach-Zehnder interferometers

Waveguide-type wavelength demulti/multiplexers (WDM) with non-sinusoidal filtering characteristics for optical communication systems are demonstrated using Mach-Zehnder interferometers, (MZI) composed of point-symmetrically connected MZI optical couplers. Three types of WDM, (1) a 1.3/1.55 μm wide-band WDM, (2) a partially-coupled 1.3/1.55 μm wide-band WDM for fiber line testing, and (3) a 1.3 & 1.55/1.65 μm WDM were designed by appropriately setting the wavelength characteristics of the directional couplers and the path differences of the waveguide arms in the MZI-WDMs. These WDMs were fabricated using silica-based planar lightwave circuit technology, and the measured results were in good agreement with the designed characteristics. © 1998 Scripta Technica, Electron Comm Jpn Pt 2, 81(4): 19–28, 1998