| 摘要 |
PURPOSE:To simplify the constitution by applying a phase modulation to a fiber itself. CONSTITUTION:An incident light of a frequency f0 is separated into two directions by a beam splitter 2. A reflected light of the beam splitter 2 is made incident on an optical fiber 5. The light which has been made incident on the fiber 5 is reflected by a mirror 51, and thereafter, returned again into the fiber 5 and a delay time is given, and also when the light goes forward and backward in the fiber, it is subjected to a frequency shift of two times by a frequency fm by a modulating means, and the frequency becomes f0+ or -2fm. An emitted from the fiber 5 transmits through the beam splitter 2, and thereafter, reflected by a mirror 21 and returned to the beam splitter 2, and made incident on a photodetector 7. On the other hand, the light which has transmitted through the beam splitter 2, in the incident light is made incident on the photodetector 7 in a state of the frequency f0 as a reference light. The lights which have passed through two optical paths interfere with each other by the photodetector 7, and the 2fm component is displayed by a spectrum analyzer which has been connected to the photodetector 7. |
