| 摘要 |
PURPOSE:To enable the evaluation of noise characteristics in high preciseness, by a method wherein light from a light source to be measured is passed through a fiber tunable etalon having zone limiting effect to convert the fluctuation of center frequency to amplitude modulation which is, in turn, detected by a light detector to be converted to an electric signal. CONSTITUTION:The light from a light source 11 is applied to a fiber tunable etalon 12 through a transmission path and, after passed through to etalon 12, applied to a light detector 13. The output of the detector 13 is supplied to a narrow zone level meter or a measuring instrument 14 such as a spectrum analyser. When the light is passes through the fiber tunable etalon 12, it is converted to the output as shown by the broken line 21 is the central wavelength lambda0 is coincided with the wavelength showing the max. permeability in etalon characteristics. When there is fluctuation in the wavelength of the light from the light source, amplitude is limited as shown by the broken line 22. This is outputted in such a state that the change of the wavelength is converted to the change of amplitude. As the result, AM, FM noise characteristics of the light from the light source can be measured in high sensitivity. |
