Optical evidence for dimensionality crossover: the case of ladder systems and Bechgaard salts.

We compare our optical data collected in two families of low dimensional correlated electron systems: the ladders and the organic Bechgaard salts. Our data display a remarkable optical anisotropy between the spectra along the three crystallographic axes, indicative of the low dimensionality in the electronic band structure. Moreover, we optically identify a dimensionality crossover, induced by Ca-doping in the ladders and by chemical pressure in the Bechgaard salts.