To provide a compact optical modulating element with high efficiency which has a photonic crystal structure as a portion of itself, an optical switching element, an element structure of a nonlinear optical control element, a manufacturing method, operations, and an evaluating method.

An element which has a nonlinear material and a photonic crystal structure inside is used and an optical band mode is generated in the element to vary the refractive index of the nonlinear material with external control light; and the band structure is dynamically controlled to perform optical control over signal line in a compact area with very high efficiency.