| 摘要 |
PURPOSE:To attain the driving power transmission of a Josephson element or the like in a cryogenic space and the signal transmission between a normal temperature space and the cryogenic space with good thermal shield efficiency by constituting a signal and energy transmission line tying the cryogenic space and the normal temperature space by using an optical fiber. CONSTITUTION:An input electric signal is converted into an optical signal at the normal temperature space, then converted into an electric signal at a photoelectric converting element 6 via the optical fiber 5, in the operation of the signal transmission line from the normal temperature space 1 to the cryogenic space 2. As the photoelectric converting element 6 a photo transistor (TR) or the like operationable at a power as low as nearly 1mW or below is suitable. Since the optical energy for the signal is only >=1muW in this case other than the case with optical power feeding, the heating by the signal light is not a problem. That is, Since the heat of nearly >=1mW is generated when the optical fiber and the photo TR are used while thermal flow of 60mW occurs with a pair of copper wire, the thermal stability is improved considerably. |
