Multi-functional waveguide structures

  • Kristensen, Martin (Project Manager)
  • Laurent-Lund, Christian (Project Participant)
  • Pedersen, Jens Engholm (Project Participant)

    Project Details


    When designing planar waveguides it is of great interest to be able to separate different functions physically. One very important example is in the design of erbium doped planar waveguide devices. The rare earth element erbium is incorporated in the core of the waveguides to provide optical gain and compensate for losses. Furthermore, the incorporation of erbium also makes possible the fabrication of integrated lasers. However, if all of the waveguides in such a device are erbium doped it becomes impossible to maintain population inversion throughout the whole of the device when realistic laser diode pump power levels are considered. This sets a strict limit on the splitting ratio that can be obtained in loss-less splitters. To overcome this problem the device must be designed with two different types of glass in the core: passive and active (erbium doped). Other examples are the integration of ordinary waveguides with UV-written waveguides, as well as the integration of glasses with different refractive indices. The latter can be used for device miniaturisation.
    The glass deposition method used is planar which ensures that when depositing a layer, e.g. core layer, the properties of the glass are constant over the entire wafer. Thus, in order to incorporate two different types of core glasses some sort of multilevel integration will be necessary. However, true multilevel integration might not be the best solution. The reason for this is the losses experienced due to mismatch of the phase velocity when coupling between the layers. It is imposible to obtain good phase matching, particularly when two different wavelengths must be coupled between layers with different properties.
    At MIC we have therefore developed new advanced processes for meeting the challenge of integrating two or more different glasses in the same plane.
    Effective start/end date01/01/199631/12/1999