Dispersion analysis and tunable magnetic properties of a biaxial hyperbolic metamaterial based on n-GaAs/AlGaAs heterostructures

This study presents the design and theoretical analysis of a tunable biaxial hyperbolic metamaterial (BHMM) constructed from a layered n-GaAs/AlGaAs heterostructure under an external magnetic field. The objective is to optimize the tunability in order to control the dispersion shape for applications in the terahertz (THz) frequency regime. The effective medium approximation (EMA) model is employed and demonstrates the coexistence of two wave modes, namely, a closed ellipsoidal and an open hyperboloidal isofrequency surface. The results reveal that the external magnetic field acts as a powerful tuning mechanism, enabling spectral shifting of the dispersion and active switching between Type-I and Type-II hyperbolic regimes. In addition, the conditions required to achieve extreme compression of the isofrequency surface (IFS), which is essential for beam steering control, are analyzed. This compression occurs when one component of the permittivity reaches extremely large values, leading to the formation of near-flat segments on the isofrequency surface.

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