Monolithically integrated multiple wavelength oscillator on silicon

Abstract

Silicon photonics enables on-chip ultra-high bandwidth optical communications networks which is critical for the future of microelectronics1,2. By encoding information on-chip using multiple wavelength channels through the process of wavelength division multiplexing (WDM), communication bandwidths in excess of 1 Tbit s-1 are possible3. Already several optical components critical to WDM networks have been demonstrated in silicon, however a fully integrated multiple wavelength source capable of driving such a network has not yet been realized. Optical amplification, a necessary component for producing a source, can be achieved in silicon through stimulated Raman scattering4,5, parametric mixing6, and the use of silicon nanocrystals7 or nanopatterned silicon8. Losses in most of these previously demonstrated devices have prevented oscillations in those structures. Raman oscillators have been demonstrated9-11, but the narrow Raman gain window limits operation to a tightly restricted (~ 1 nm) wavelength range and thus is insufficient for WDM. Losses in other previously demonstrated devices have prevented oscillations in those structures. Here we demonstrate the first monolithically integrated CMOS-compatible multiple wavelength source by creating an optical parametric oscillator (OPO) formed by a silicon nitride ring resonator on silicon coupled to an integrated waveguide. The device can generate more than 100 new wavelengths, spaced by a few nm, with operating powers below 50 mW. This source can form the backbone of a fully operational high-bandwidth optical communications network on a microelectronic chip enabling the next generation of multi-core microprocessors.