A two-dimensional photonic crystal formed by arranging in a lattice
pattern a medium having a refractive index different from that of a
medium layer formed near an active layer. The two-dimensional photonic
crystal includes a distributed-feedback control photonic crystal in which
a light propagating through the active layer as a core is subjected to a
two-dimensional distributed feedback within a plane of the active layer,
and the light is not radiated in a direction normal to the plane of the
active layer, and a surface-emission control photonic crystal in which
the light is radiated in the direction normal to the plane of the active
layer, which are superimposed with each other.