Optical properties of low-dimensional systems: The Bechgaard salts case

We review our optical investigations on the organic Bechgaard salts. These prototype quasi-one dimensional systems reveal non-Fermi liquid features in their electrodynamic response. We show that various aspects of the exotic normal state properties along the chains are consistent with the prediction s of the Tomonaga- Luttinger liquid theory or Luther-Emery model for one-di mensional systems. The role played by the interchain coupling will be also addressed.