Two-dimensional photonic-crystal surface-emitting laser

A two-dimensional photonic-crystal surface-emitting laser comprising:

• a) an active layer configured to emit light by supplying an electric current;
• and
• b) a photonic-crystal layer including
• b-1) a two-dimensional photonic-crystal light-amplification portion that is a first two-dimensional photonic-crystal region provided, for introducing the light emitted from the active layer, in a plate-shaped base body disposed on one side of the active layer, and includes an amplification-portion photonic band gap which is a photonic band gap formed between two photonic bands having a band edge at a predetermined point in a reciprocal lattice space, and
• b-2) a two-dimensional photonic-crystal light-reflection portion that is a second two-dimensional photonic-crystal region provided around the two-dimensional photonic-crystal light-amplification portion, and includes a reflection-portion photonic band gap which is a photonic band gap formed between two photonic bands having a band edge at the predetermined point of the reciprocal lattice space,
• wherein energy ranges of the amplification-portion photonic band gap and the reflection-portion photonic band gap partially overlap and are different, and
• wherein, when the electric current is supplied into the two-dimensional photonic-crystal light-amplification portion, an energy of a lower band edge of the amplification-portion photonic band gap does not exceed an energy of a lower band edge of the reflection-portion photonic band gap.