Light intensity attenuator and attenuating method

摘要

PCT No. PCT/JP98/04346 Sec. 371 Date Jun. 1, 1999 Sec. 102(e) Date Jun. 1, 1999 PCT Filed Sep. 20, 1998 PCT Pub. No. WO99/17472 PCT Pub. Date Apr. 8, 1999A light intensity attenuator and attenuating method is provided, by which a pulse-shaped optical surge can be attenuated and an optical signal component using desired light intensity can be output by using a simpler structural arrangement, and without using many optical components and circuits. In this method, an optical signal including a pulse-shaped optical surge component is received, and the optical signal is again output after the light intensity of the surge component is attenuated by a desired amount. Typically, (i) at least one of a substrate and an optical waveguide formed on the substrate is made of a material producing a nonlinear optical effect, and the refractive index of the optical waveguide with respect to the optical signal is smaller than the refractive index of the substrate with respect to a higher harmonic of the optical signal, thereby wavelength-converting a part of the input optical signal by the nonlinear optical effect into a light portion having a wavelength shorter than that of the optical signal, and scattering this converted portion, and (ii) a part of the optical signal is scattered by using a polar-molecule liquid including polar molecules.