2D and 3D photonic crystals

Photonic crystals are materials designed to control and manipulate light, similar to how semiconductors control electrical flow. **2D photonic crystals** have a repeating pattern in two dimensions, affecting light traveling within a plane—think of a patterned surface or a thin film with tiny holes or shapes that guide light horizontally. **3D photonic crystals** have a repeating structure throughout all three dimensions, creating a complex lattice that can control light in all directions—like a crystal with a precisely arranged internal pattern. Both are used to develop advanced optical devices, such as highly efficient lasers and optical fibers.