According to one embodiment, in the upper laminated structure, first layers and second layers are alternately laminated, the first layer and the second layer having different refractive indices. In the lower laminated structure, first layers and second layers are alternately laminated, the first layer and the second layer having different refractive indices. The upper laminated structure and the lower laminated structure are equal in number of layers laminated therein. Each of the lowermost layer of the upper laminated structure and the uppermost layer of the lower laminated structure are configured by the first layer. The upper laminated structure and the lower laminated structure are configured to be asymmetric to each other such that, within some layer sets out of a plurality of layer sets each including two layers disposed at corresponding positions in the upper and lower laminated layers, one layer of the two layers in each layer set of the some layer sets is thinner than the other layer.