To provide an optical switch including an optical system which generates a coherent excitation by the first light pulse and maintains coherence until out of excitation by the second light pulse.

An optical switching apparatus includes an optically responding system 3 and pulse source structures 1, 2 for guiding the first and second pulse components P1, P2 to the optical system. The first pulse component P1 is set so as to generate the coherent excitation to change a light characteristic. The second pulse component P2 has a phase for generating the out of the excitation after the coherent excitation generated by the first pulse component P1. A device such as an optical amplifier or a laser, etc., drivable from the outside of a resonance system maintains the coherence of the excitation generated by the first pulse until the out of the excitation by the second pulse.