Multi-channel Race-track shaped resonators for photonic analog to digital converter

Progress in developing high speed ADC's occurs rather slowly - at a resolution increase of 1.8 bits per decade. This slow progress is mostly caused by the inherent jitter in electronic sampling - currently on the order of 250 femtoseconds in the most advanced CMOS circuitry. Advances in femtosecond lasers and laser stabilization have led to the development of sources of ultrafast optical pulse trains that show jitter on the level of a few femtoseconds over the time spans of typical sampling windows and can be made even smaller. We discuss and demonstrate strategies and an important device that enables the implementation of photonic ADC systems with emerging electronic-photonic integrated circuits based on silicon photonics. The microring resonators are designed to have 20nm Free-Spectral Range (FSR) and 25 GHz bandwidth, allowing for a channel spacing of 80 GHz with less than 30 dB of crosstalk and similar to 350x350 mu m(2) size of race-track resonator that to the best of our knowledge, this is the smallest size of 20 channel second order filter bank for wavelength De-multiplexer in a silicon chip.