Two-dimensional photonic crystal laser

A two-dimensional photonic crystal laser array comprising:

• a) a pair of electrode groups including electrode groups of which at least one group includes a plurality of partial electrodes;
• b) an active layer provided between the pair of electrode groups and, upon being supplied with an electric current from one of the plurality of partial electrodes, configured to generate light including a predetermined wavelength 2 at a position corresponding to the partial electrode from which the electric current is supplied;
• and
• c) a two-dimensional photonic crystal layer provided between any one of the pair of electrode groups and the active layer and including a plate-shaped base member and a plurality of modified refractive index regions disposed in the base member and having a refractive index different from a refractive index of the base member, wherein
• at a corresponding one of lattice points of a square lattice in which the lattice points are periodically disposed with a lattice point period corresponding to the predetermined wavelength 2L, each of the plurality of modified refractive index regions is disposed to be shifted from the lattice point in one predetermined direction or a direction different from the one direction by 180°, the one direction being a direction parallel to the two-dimensional photonic crystal layer and inclined from both two directions in which the lattice points are disposed with the lattice point period, and
• in a direction parallel to the two-dimensional photonic crystal layer, a distance from the lattice point or/and an area of a planar shape of each of the plurality of modified refractive index regions is/are modified with a composite modulation period in which a plurality of periods different from each other are superposed on each other, and is/are expressed by a modulation phase Ψ(r↑) expressed using a vector r↑ indicating a position of each of the lattice points of the two-dimensional lattice, a vector kn↑ indicating a combination of an inclination angle and an azimuthal angle of each of n (n is an integer of 2 or more) laser beams differing in the inclination angle and/or the azimuthal angle from each other, and an amplitude An and a phase exp(iαn) determined for each n as
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• the amplitude An and/or the phase exp(iαn) for each value of n differ(s) from each other in at least two different values of n.