Γ-point group velocity of lossy Dirac cone composite right/left-handed metamaterials

Abstract

The Γ-point group velocity, v_gΓ, of lossy Dirac cone composite right/left-handed (CRLH) metamaterials is derived theoretically for the first time based on the equivalent circuit analysis. With the balanced CRLH condition, it is theoretically shown that v_gΓ takes the maximum value of a half of the speed of light in the background medium under the condition where the quality factors of the resonators in the series and shunt branches in the unit cell, Q_se and Q_sh, are equal, whereas under the condition of Q_se ≠ Q_sh, v_gΓ becomes smaller with the slow wave factor of κ = (k^1/2 + k^−1/2)⁻¹ where k is the quality factor ratio k = Q_sh/Q_se.