What is the primary function of a photonic crystal?

The primary function of a photonic crystal is to manipulate light propagation and create photonic band gaps. Photonic crystals are optical materials that have periodically varying refractive indices, which allows them to affect the movement of photons in a way similar to how semiconductors affect electrons.

By designing the structure of a photonic crystal, it is possible to create band gaps that prevent certain wavelengths of light from propagating through the material. This characteristic is utilized in various applications such as optical fibers, waveguides, and light-emitting devices. The ability to control light in such a precise manner is crucial for the development of advanced optical devices, making photonic crystals a vital component in the field of opto-electronics.

The other options, while related to different technologies, do not encompass the defining characteristic of photonic crystals. Generating electrical energy and storing digital information pertain to other technologies, such as solar cells or memory devices, while enhancing thermal insulation involves materials typically used in thermal management rather than manipulation of light.