Mid-IR broadband supercontinuum generation from a suspended silicon waveguide.

Mid-infrared light provides numerous unexpected opportunities in scientific discoveries because this wavelength region covers the fingerprints of various molecular vibrational resonances. However, the light generation efficiency and bandwidth have been a long-standing bottleneck which has limited the development so far. Moreover, the light source that can be integrated with other components such as wavelength filters, detectors, and electronics, will be the key factor toward the future practical applications.

Experimental Realization of Two Decoupled Directional Couplers in a Subwavelength Packing by Adiabatic Elimination.

On-chip optical data processing and photonic quantum integrated circuits require the integration of densely packed directional couplers at the nanoscale. However, the inherent evanescent coupling at this length scale severely limits the compactness of such on-chip photonic circuits. Here, inspired by the adiabatic elimination in a N-level atomic system, we report an experimental realization of a pair of directional couplers that are effectively isolated from each other despite their subwavelength packing.

Adiabatic elimination-based coupling control in densely packed subwavelength waveguides.

The ability to control light propagation in photonic integrated circuits is at the foundation of modern light-based communication. However, the inherent crosstalk in densely packed waveguides and the lack of robust control of the coupling are a major roadblock toward ultra-high density photonic integrated circuits. As a result, the diffraction limit is often considered as the lower bound for ultra-dense silicon photonics circuits.