Integrated nonlinear optical signal processing in CMOS compatible platforms

Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically — particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics for some time, its high two-photon absorption at telecommunications wavelengths poses a fundamental limitation. We review the recent achievements based on new CMOS-compatible platforms that show great promise for nonlinear optics, focusing on amorphous silicon and Hydex glass, that have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement.