Efficient supercontinuum generation enabled by dispersion engineering in a dual-core waveguide

A compact dual-core waveguide is proposed for efficient supercontinuum generation, in which the use of Si-rich nitride and titanium dioxide provides a large enough index contrast for dispersion engineering. Strong anomalous group velocity dispersion is obtained over a wide bandwidth of 1860 nm which greatly reduces the dispersion length. The nonlinear length can also be significantly decreased due to high nonlinear Kerr index of Si-rich nitride. As a consequence, it could facilitate octave-spanning supercontinuum generation from 1160 to 2385 nm in a greatly reduced propagation distance, as short as 165 mu m. It is more than one order of magnitude shorter than those previously reported and can be further reduced to 70 mu m. This compact broadband source is promising not only for on-chip applications but also for applications in tiny environments such as nano-scale spectroscopic probing and study of biological molecules, cells and tissues.