Photonic crystal

Lore & Background

Yablonovitch aimed to engineer photonic density of states to control spontaneous emission, while John sought to use photonic crystals for light localization and control. Early research was largely theoretical or conducted in the microwave regime due to fabrication challenges at optical scales. Later, Pavel Cheben introduced the subwavelength grating (SWG) waveguide, a new type of photonic crystal waveguide operating away from the bandgap.

Reader's Guide

Photonic crystals are significant because they provide a means to manipulate light in ways analogous to how semiconductors control electrons, enabling technologies such as ultra-high reflectivity mirrors, photonic-crystal fibers for fiber-optic communication, and potential future applications in optical computers and more efficient photovoltaic cells. The concept of a photonic band gap—a range of wavelengths that cannot propagate through the structure—arises from destructive interference of multiple reflections at interfaces between regions of high and low refractive index. Fabrication methods vary by dimension: one-dimensional crystals use thin-film deposition; two-dimensional ones use photolithography or drilling; three-dimensional ones involve drilling at different angles, stacking 2-D layers, direct laser writing, or self-assembly of spheres. Despite the name, analysis of photonic crystals requires only classical physics, and the term 'photonic' refers to the study of light (photonics).

Did You Know?

• Photonic crystals occur naturally as structural coloration and animal reflectors.
• Three-dimensional photonic crystals may one day be used in optical computers and more efficient photovoltaic cells.