"Version: 20251201"--Title page verso.Includes bibliographical references.1. A new era of tailor-made optical media -- 1.1. Structural evolution : from composites to artificial atoms -- 1.2. The l/a rule : when structure matters -- 1.3. Quest for a negative refractive index2. Effective medium of metamaterials -- 2.1. Constitutive relationship -- 2.2. Understanding metamaterials with a dipolar m…