Adaptive gain and channel equalization filters for applications in optical networks

We present two dynamically reconfigurable filter components, an adaptive gain flattening filter and a variable channel equalizer. The channel equalizer is able to set the optical power of up to eight WDM channels individually over a dynamic range of at least 10 dB, the gain equalizer flattens the response of optical amplifiers across a spectral range of more than 40 nm in the 1550 nm window. Reconfigurability is obtained via thermo-optic tuning of the cascaded resonant coupler (RC) segments. The devices are realized in high-index contrast SiON technology. The experimental accuracy of the attenuation across the full band is around 1 dB, which can be further improved by using more delay line stages.