Abstract: An object is to provide an optical communication system and an optical communication method that are capable of, when assigning wavelengths on a per-service basis and providing services on a per-area basis, preventing degradation of signal quality due to linear crosstalk and preventing an increase in cost and size. An optical communication system according to the present invention includes an optical splitter 300 connecting N first ports and M second ports by a combination of 2×2 fiber optical splitters, N and M each being an integer of two or more, where wavelengths of optical signals to be received are limited for each group of optical receivers 106, by using a correlation between a fused extension length of at least one 2×2 fiber optical splitter directly connected to the first port, among the 2×2 fiber optical splitters, and wavelength output characteristics of the second port of the optical splitter 300.

Abstract: An object is to provide an optical communication system capable of controlling the output ratio by port and by wavelength for incident light of different wavelengths, a method of determining the split ratio of an uneven-split optical splitter for controlling the output ratio by port and by wavelength, and a transmission range determination method for the optical communication system. The split ratio determination method for an uneven-split optical splitter according to the present invention uses the melt-draw distance to adjust the split ratio of each fiber-optic splitter included in the uneven-split optical splitter such that the light output from the farthest ONUs among each of the ports connected under the ports B to M of the uneven-split optical splitter arrives with the minimum reception sensitivity at OLT receivers in a PON system.

Abstract: An object is to provide an optical communication system and an optical communication method that are capable of, when assigning wavelengths on a per-service basis and providing services on a per-area basis, preventing degradation of signal quality due to linear crosstalk and preventing an increase in cost and size. An optical communication system according to the present invention includes an optical splitter 300 connecting N first ports and M second ports by a combination of 2×2 fiber optical splitters, N and M each being an integer of two or more, where wavelengths of optical signals to be received are limited for each group of optical receivers 106, by using a correlation between a fused extension length of at least one 2×2 fiber optical splitter directly connected to the first port, among the 2×2 fiber optical splitters, and wavelength output characteristics of the second port of the optical splitter 300.

Abstract: An object is to provide an optical communication system capable of controlling the output ratio by port and by wavelength for incident light of different wavelengths, a method of determining the split ratio of an uneven-split optical splitter for controlling the output ratio by port and by wavelength, and a transmission range determination method for the optical communication system. The split ratio determination method for an uneven-split optical splitter according to the present invention uses the melt-draw distance to adjust the split ratio of each fiber-optic splitter included in the uneven-split optical splitter such that the light output from the farthest ONUs among each of the ports connected under the ports B to M of the uneven-split optical splitter arrives with the minimum reception sensitivity at OLT receivers in a PON system.

Abstract: To provide an optical communication system and an optical communication method able to achieve a high reliable access network capable of long haul distance transmission considering the optical energy efficiency even if the user distribution is biased. An uneven branch optical splitter included in an optical communication system according to the present invention can output the optical intensities different for each output port by adjusting the branching configuration and the branching ratio. For example, a reach transmission distance of the farmost user can be extended or the number of connectible users can be increased by adjusting the branching configuration of the uneven branch optical splitter or the branching ratios such that the near minimum reception sensitivity is given for the ONU installed near the telecommunications carrier.

Abstract: To provide an optical communication system and an optical communication method able to achieve a high reliable access network capable of long haul distance transmission considering the optical energy efficiency even if the user distribution is biased. An uneven branch optical splitter included in an optical communication system according to the present invention can output the optical intensities different for each output port by adjusting the branching configuration and the branching ratio. For example, a reach transmission distance of the farmost user can be extended or the number of connectible users can be increased by adjusting the branching configuration of the uneven branch optical splitter or the branching ratios such that the near minimum reception sensitivity is given for the ONU installed near the telecommunications carrier.

Abstract: A method and apparatus for decontaminating a substance contaminated with radioactivity, in particular, shot blasting grit contaminating with radioactivity. The method comprises: contaminated substance washing the substance to be decontaminated with chelate liquid; draining the chelate liquid; raising the temperature of the substance to a level not lower than the boiling point of a solvent by means of hot air; supplying the solvent to the substance and rapid by vaporizing the solvent; removing the remaining chelate fluid liquid by the force of the vaporization and draining and drying the substance.