| 摘要 |
<P>PROBLEM TO BE SOLVED: To eliminate difficulty caused in the case that it is usually difficult for a local light source provided in a detecting unit to satisfy conditions that signal light and reference light must have the same wavelengths, the phase relation must be constant in an optical detecting method requiring the reference light such as homodyne detection, and the difficulty is specifically large when minute signal light is transmitted in the case of quantum communication. <P>SOLUTION: The signal light and the reference light which are taken out of the same light source have the same wavelengths. However, if both the lights are transmitted in a long distance, a constant phase relation cannot be maintained between both the lights because of the difference in the external environment of transmission paths for the both. Therefore, by transmitting the signal light and the reference light so as to be overlapped in terms of time with polarized light orthogonal to the same optical path, both the lights have the same external environments and the constant phase relation can be maintained. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
