Silicon-on-insulator (SOI) micro-ring resonator (RRs) demonstrated to be a versatile building block to realize integrated optical filters for several telecom and sensing applications, providing unique features in terms of large bandwidth, footprint reduction and quality factor enhancement. Demanding spectral specifications, such as sharp pass-band transitions, can be achieved with higher order filters made by suitably cascading multiple RRs . However, the high index contrast of SOI platform makes these devices very sensitive also to small inaccuracies in the fabrication process. This produces, even with a state-of-the-art technology, a spectral spreading of the resonance positions, which quickly deteriorates the response of the filter. An accurate control of the resonance frequencies is therefore a challenging issue, which generally requires further fabrication steps, complex algorithms and power consumption techniques .
© 2011 Optical Society of AmericaPDF Article