| 摘要 |
PURPOSE:To utilize the energy of an optical signal in the transmission of a signal to a maximum by selecting the wavelength of light energy for power supply and that of the optical signal for signal transmission setting them differently from each other, and transmitting the optical signal corresponding to a process variable. CONSTITUTION:Short wavelength light having wavelength lambda1 from a laser diode 13 and long wavelength light having wavelength lambda2 from a laser diode 14 are sent to an optical fiber 12 via a directional coupler 19, respectively. In such a case, the short wavelength light is absorbed in a silicon solar battery 24, then, an electromotive force is generated. and it is outputted to a power source 25 which generates a power source for a circuit, and the long wavelength light transmits the silicon solar battery 24, and is outputted to a shutter 26. Here, the process variable PV detected by a sensor 29 is inputted to a driving circuit 27, which opens and closes the shutter 26 via the driving circuit 27, and the long wavelength light is modulated corresponding to the process variable PV, and the modulated light is reflected on a mirror 28, and is sent to an optical fiber 20 via the silicon solar battery 24. In such a way, it is possible to increase supply energy and to improve efficiency. |
