Yoshiki Chigusa

Gamma-ray radiation hardened properties of pure silica core single-mode fiber and its data link system in radioactive environments

The radiation resistances of pure silica core single-mode optical fiber (Si-SMF) and its data link module at 1.30 mu m were investigated. It was found that the induced loss of fibers exposed to gamma -rays at a low dose rate was proportional to the 0.54 power of total dose from the result of a low dose rate irradiation test for 3 years, and the induced loss for 40 years aging at 1 R/h was estimated to be 1.8 dB/km. It was ascertained that transmission is achievable at a bit rate of 125 Mb/s even under high dose rate irradiation to a total dose of 10/sup 8/ R, which corresponds to the postulated maximum gamma -ray exposure in nuclear power plants. >

Low-loss pure-silica-core fibers and their possible impact on transmission systems

Low-loss optical fibers are now indispensable transmission media for transmission systems. Recently, the ultralow-loss performance for long transmission systems, the water-loss-free performance for wide-band wavelength-division-multiplexing (WDM) systems, the hydrogen-loss-insensitive performance for system reliability, and the bending-loss-insensitive performance for access or indoor applications have attracted much interest. In this regard, pure-silica-core fibers (PSCFs) are suitable, and unprecedented low-loss PSCFs have been successfully fabricated. This paper introduces the recent progress of low-loss PSCFs and their possible impact on transmission systems.

Bi−Pb−Sr−Ca−Cu−O superconducting fibers drawn from melt-quenched glass preforms

Bi-Pb-Sr-Ca-Cu-O glass fibers were drawn from melt-quenched glass preforms by the method that is ordinarily applied to optical fiber fabrication. The drawn fibers were very flexible, and their surfaces were smooth. The glass fibers were crystallized by annealing and had superconducting properties. The annealed (1133 K, 240 hour) Bi1.6Pb0.4Sr2Ca2Cu3Ox fiber exhibited superconductivity with a Tc(zero) of 68 K and a critical current density (30 K, zero magnetic field) of 22 A/cm2.

Preparation of Bi1.5SrCaCu2Ox Glass Fibers Using Melt-Quenched Glasses

Bi1.5SrCaCu2Ox glass preforms were prepared by the melt-quenching method, and their thermal characteristics and viscosity were investigated to determine the possibility of drawing them into glass fibers. Furthermore, Bi1.5SrCaCu2Ox glass fibers were drawn from glass preforms by the method that is ordinarily applied to optical fiber fabrication. The drawn fibers were very flexible, and the maximum length was 1200 mm.

Gamma-Ray Irradiation Effect on Loss Increase of Single Mode Optical Fibers, (I): Loss Increase Behavior and Kinetic Study

Gamma-ray induced losses of pure silica core and GeO2 added core single mode optical fibers (Si-SMF and Ge-SMF) at 1.30 μm were investigated. Kinetic study on recovery curves of their γ-ray induced losses, showed that the induced loss could be divided approximately into two terms: one is dependent mainly on total dose and the other is dependent on dose rate, which has a tendency toward saturation when increasing total dose and was also represented by 3 components with different relaxation times The former term which is dependent mainly on the total dose was found to be due to IR tail absorption caused by irradiation and to be associated with the Si-E′ center for the Si-SMF and the Ge(l) and Ge(2) centers for the Ge-SMF, respectively.

Gamma-ray irradiation effect on loss increase of single mode optical fibers, II. Estimation of loss increase due to long term irradiation

In order to examine the reliability of optical fiber systems in nuclear power plants, we estimated the induced losses of pure silica core and GeO 2 added core single mode optical fibers (Si-SMF and Ge-SMF) exposed over a long period to low dose rate γ-rays (less than 100 R/h, 40 yr). Also γ-ray induced losses under a high dose rate and high temperature condition such as 10 6 R/h and 200 o C were estimated in view of an accident. In both cases, the induced losses were concluded to depend mainly on total dose from the results of low dose rate irradiation experiments and a study on temperature dependences of induced losses

Modulation Transfer Function (MTF) Measurement of Silica Glass Image Fiber

When an image is transmitted by an image fiber, the image quality at the exit end of the fiber generally deteriorates in relation to the size of each picture element, the misalignment of each picture element, optical power coupling (leakage) between adjacent picture elements and defects in the picture elements.

Radiation-resistant characteristics of image fiber

γ ray irradiated characteristics of radiation resistant image fiber was mainly studied, and also core material and cladding material were investigated. We have got the following result.