Reconfigurable non-reciprocal wave growth in spatiotemporal modulated 1-D crystal

Nonreciprocity in space-time modulated photonic crystals has been investigated in the context of nonreciprocal propagation and polarization. Here, we investigate a reconfigurable nonreciprocal wave growth in space-time modulated crystals. Imposing an adaptable progressive phase shift between successive time-modulated cells results in blue and red shifts of the forward and backward momentum band gaps around the typical 0.5 growth normalized frequency. We applied this spatiotemporal scheme to engineering the dispersion relation of a loaded transmission line$-$a 1D periodic structure$-$in the microwave regime.