| 摘要 |
<p>PURPOSE:To make possible the constitution of a linear monitoring system by making use of the characteristic that attenuation arises in the light transmitting a quartz optical fiber doped with P2O5 in the wavelength region above the specific wavelength if said optical fiber is in a submerged region. CONSTITUTION:The exit light from a long wavelength light source 6 having >=1.0mum wavelength and short wavelength light source 6' having <=1.0mum wavelength are multiplexed by a synthesizer 12 and the multiplexed light is transmitted through the optical fiber 7 doped with P2O5. The transmitted light is demultiplexed to the long wavelength light having >=1.0mum wavelength and short wavelength light having <=1.0mum wavelength. The demultiplexed light are respectively inputted to photodetectors 9, 10 and are converted to electric signals. The long wavelength light above 1.0mum attenuates with an increase in the transmission loss of the fiber 7 but the short wavelength light below 1.0mum attenuates less if the fiber 7 is submerged. The light output having >=1.0mum wavelength is therefore divided by the light output having <=1.0mum wavelength in a divider 11, then the degree of the submergence of the optical fiber is known by the long wavelength with time.</p> |
