Phased-Array WDM Devices

  • Kristensen, Martin (Project Manager)

    Project Details


    Power combiners may be used to add optical signals with different wavelengths into a single optical fibre. Separating these signals requires a wavelength dispersive component or WDM. Most WDM's are based on a phased-array which can be thought of as a diffraction grating made from channel waveguides. It consists of an array of single mode waveguides, which are connected between two focusing slab waveguides. The input and output waveguides are connected at the ends of the slabs.
    The ends of the input and output waveguides as well as the array waveguide ends are arranged on an arc. Each of the array waveguides is longer than its neighbour by a constant length. For the centre wavelength of the array, the path length difference between the adjacent waveguides is a multiple of that wavelength. As the fields from the array waveguides propagate through the second slab region, they are gradually converted into a single wavefront. The new wavefront will converge to one point and will be efficiently coupled into one of the output waveguides. If a plurality of wavelengths is sent into the device, each wavelength will exit the array waveguides with a slightly different angle and enter one particular exit waveguide. The centre wavelength of the array, lambda0, may be defined according to
    n c ^ L = m lambda 0
    where m is the diffraction order of the grating. MIC has fabricated two fibre pigtailed WDM prototypes for the EU project METON. We recorded the transmission spectra from the input port to each of the four output ports. After pigtailing we obtained 6-8 dB loss and better than -26 dB crosstalk.
    Effective start/end date01/01/199731/12/1999