Anomalous dispersion properties of TM waves in subwavelength metallic waveguides loaded by uniaxial metamaterials

• Two kinds of subwavelength uniaxial metamaterial waveguides are constructed.
• We demonstrate anomalous dispersion properties of transverse magnetic (TM) guided modes.
• There are two branches of dispersion curves for high-order TM modes, showing a transition from a backward wave to a forward one.
• Group velocity can approach to zero, having potential application in optical information storage.
• Negative group velocity and energy flow distribution for TM modes are shown.

Dispersion properties of transverse magnetic (TM) waves in a subwavelength metallic waveguide loaded by uniaxial metamaterials are investigated, based on two kinds of uniaxial metamaterials with different orientations of optical axis. The numerical results show that the existence of fundamental TM0 mode and high-order TM modes in the waveguide system is dependent on the orientation of optical axis. In addition, their anomalous dispersion properties are clarified. When the orientation of optical axis is selected properly, there are two branches of dispersion curves for each high-order mode—one is normal dispersion and another belongs to anomalous dispersion, showing a transition from a backward wave to a forward one with the increase of working frequency. Moreover, the group velocity and energy flow distribution for TM1 mode are also demonstrated. These properties may have potential applications in optical information storage, integrated optics and nanophotonic devices.