Meta-waveguide

In photonics, a meta-waveguide is a physical structures that guides electromagnetic waves with engineered functional subwavelength structures.^[1] Meta-waveguides are the result of combining the fields of metamaterials and metasurfaces into integrated optics.^[2][3] The design of the subwavelength architecture allows exotic waveguiding phenomena to be explored.^[3][4]

Meta-waveguides can be classified by waveguide platforms or by design methods.^[2] If classified by underlying waveguide platform, engineered subwavelength structures can be classified in combination with dielectric waveguides, optical fibers, or plasmonic waveguides. If classified by design methods, meta-waveguides can be classified as either using design primarily by physical intuition, or by computer algorithm based inverse design methods.^[1][5]

Meta-waveguides can provide new degrees of design freedom to the available structural library for optical waveguides in integrated photonics.^[1][3] Advantages can include enhancing the performance of conventional waveguide based integrated optical devices and creating novel device functionalities.^[1][3] Applications of meta-waveguides include beam/polarization splitting,^[3] integrated waveguide mode converters,^[4] versatile waveguide couplers,^[6] lab-on-fiber sensing,^[7] nano-optic endoscope imaging,^[8] on-chip wavefront shaping,^[9] structured-light generations,^[10] and optical neural networks.^[11][12] The meta-structures can also be further integrated with van der Waals materials to add more functionalities and reconfigurability.^[13][14]