Direct writing of planar waveguides with ultraviolet light

  • Kristensen, Martin (Project Manager)
  • Svalgaard, Mikael (Project Participant)
  • Rathje, Jacob (Project Participant)
  • Zauner, Dan (Project Participant)

    Project Details


    Irradiating germanium doped silica - the building block of modern fiber optical communication - with intense ultraviolet (UV) light can permanently increase the refractive index of the glass. The index changes are sufficiently large to permit direct UV writing of planar waveguides on silicon wafers using a focussed UV laser beam by translating the sample on high precision, computer controlled stages.
    We shown that this technique permits fabrication of a wide variety of waveguide devices such as directional couplers and power splitters for use in the telecommunications industry. In the past year we have focussed on problems of direct relevance to possible industrial implementation of the direct UV writing technique. The results obtained in the past year include: 1) Low insertion loss waveguides: the total optical loss experienced across UV written waveguides has been lowered substantially by optimizing the glass structure used for UV writing. Insertion losses down to 0.1 dB across 3 cm long waveguides have been demonstrated. 2) Thermal stability: a major concern regarding UV written waveguide devices is that they might not be stable enough for real-life telecom applications where highly stable operation over 25 year lifetimes is often required. The reason for this concern is that part of a UV induced index change is unstable at any given temperature where it may slowly be erased. We have verified that UV written devices can fulfill stringent industrial stability requirements.
    In addition, we have also explored other possible applications of UV written waveguides beyond the telecommunications industry. In co-operation with other researchers at MIC we have succeded in integrating UV written waveguides with silicon based microfluid analysis systems, thereby opening up for many new possibilites in a very rapidly expanding field.
    Effective start/end date01/01/199631/12/1999