| 摘要 |
PURPOSE:To improve the measuring accuracy by inputting light having the 1st oscillation wavelength to an optical fiber by a single mode laser diode, detecting the time difference between a reference time detected from the output of the optical fiber and an output having the 2nd oscillation wavelength and finding out a wavelength dispersion factor on the basis of the detected time difference. CONSTITUTION:A pulse sent from a pulse oscillator 4 is inputted to a laser diode (LD) driving circuit 7 through a branching circuit 6. Then a single mode LD 8 is driven and light having oscillation wavelength lambda1 is outputted delayed by an optical fiber 9 and detected by a photodetecting circuit 10 to input the detected light to a synthesizing circuit 11. Although the pulse is branched by the branching circuit 6 and also inputted to the circuit 11, the phases of both inputs are adjusted and made uniform by a delay circuit 13. The wavelength of the LD 8 is converted into lambda2 by a wavelength control circuit 12 and the output of the circuit 10 is changed from lambda1 to lambda2 and outputted from the circuit 11. Consequently, the optical fiber wavelength dispersion factor can be obtained accurately. |
