Experimental demonstration of negative group delay on the coupled regime of extraordinary transmission hole arrays

Negative group delay (i.e. superluminal transmission) through perforated subwavelength hole arrays under TE (or s) polarization has been analyzed theoretically, numerically and experimentally at millimetre-waves. The underlying physics relies on the coupling of resonant anomalies and Rayleigh-Wood´s anomalies. The former resonances manifest themselves because of the grounded dielectric slab TE modes as a result of the dielectric sandwiched of the array, whereas the latter anomalies are intrinsic features of periodic gratings. The conclusions reached in this work apply to general periodic gratings within the couple regime and envisions applications in, for instance, pulse shaping.