Waveguide-free photonic chips
A naturally hyperbolic van der Waals material has enabled directional light transport without fabricated waveguides, offering a new approach for integrated photonics and on-chip optical communications.
Researchers from the University of Stuttgart and the Istituto Italiano di Tecnologia (IIT) have demonstrated a new mechanism for directing light through a naturally hyperbolic material without the need for conventional nanofabricated waveguides, opening new possibilities for photonic integrated circuits.
Published in Nature Nanotechnology, the research uses the two-dimensional material molybdenum oxy-dichloride (MoOClâ‚‚) to naturally confine and guide light.
By illuminating a nanoscale gold antenna on the material's surface with infrared laser light, the team generated highly confined optical waves that propagated along a single direction without any lithographically defined waveguide.
The effect, termed plasmon canalization, arises from the material's intrinsic crystal properties. MoOClâ‚‚ exhibits metallic behaviour along one crystallographic axis, supporting surface plasmons, while behaving as a dielectric along the perpendicular axis.
This strong optical anisotropy naturally channels light through a narrow path.
The researchers also demonstrated that the propagation behaviour can be tuned simply by changing the excitation wavelength.
Depending on the wavelength, the optical waves transitioned between hyperbolic, canalized and isotropic propagation, providing a new degree of control over on-chip light transport.
The team believes naturally hyperbolic materials could provide an alternative platform for integrated photonics by enabling directional optical routing without complex waveguide fabrication.
The approach could simplify photonic chip manufacturing while supporting future optical interconnects, nanoscale photonic circuits and integrated quantum technologies.
