An object of the present disclosure is to provide a zero
refractive index material having no ohmic loss, high compatibility with an
optical integrated circuit, and further a wide bandwidth for exhibiting a zero
refractive index.The present disclosure provides a
resonator including a plurality of divided air holes in a unit
cell, and the plurality of divided air holes includes two or more types of divided air holes different in dimension or shape, or both of them. The plurality of divided air holes may be provided at respective corners of the unit
cell. The plurality of divided air holes has a shape in which a circular, elliptical, polygonal, or star-shaped polygonal air hole is divided. In addition, the present disclosure also provides a
metamaterial including a plurality of the resonators. In addition, the present disclosure also provides an optical element and an optical device including the
metamaterial.