Katsuhisa Itoh

Low-loss fluorozirco-aluminate glass fiber

Abstract Low loss fluorozirco-aluminate glass fiber has been developed using improved glass preparation and preform fabrication techniques. A minimium los of μ m have been achieved. Fibers with 440 μm core diameter and 500 μm clad diameter have a minimum bending radius of 25 mm and a damage threshold of > 80 kW/mm 2 input power density. The fibers are potentially useful for Er: YAG laser power delivery and other infrared applications.

Pr3+ doped InF3/GaF3 based fluoride glass fibers and Ga–Na–S glass fibers for light amplification around 1.3 μm

Abstract We have developed three types of highly efficient Pr 3+ doped fiber (PDF) amplifiers around 1.3 μm based on non-oxide glasses. A Pr 3+ doped InF 3 /GaF 3 based fluoride glass fiber module (PFDM) has a gain coefficient: 0.29 dB/mW and a signal output power: 15.2 dBm (33 mW) at a pump power of 272 mW. A Pr 3+ doped chalcogenide system: Ga–Na–S (GNS) single-mode fiber has a larger gain coefficient: 0.81 dB/mW at signal wavelength of 1340 nm for signal input of −30 dBm. However, GNS–PDFs are best suited for amplification in the wavelength range of 1325–1350 nm when the input power is > −8 dBm. We propose a hybrid PDF consisting of the above two types of PDFs which has a flatter gain spectrum in the 1.3 μm wavelength region and will be able to extend the range of the wave division multiplexing (WDM) usage.

Transmission loss characteristics of fluorophosphate optical fibers in the ultraviolet to visible wavelength region

Abstract Transmission loss properties of fluorophosphate optical fibers were investigated in the 250 to 800 nm wavelength region. The fibers were fabricated by a glass-melting technology in which the core and cladding glasses were prepared by melting the raw materials in vapor atmospheres. The transmission loss of the fiber in the ultraviolet to visible wavelength region is dominated by extrinsic absorptions due to transition metal impurities. The ultraviolet absorption tail is a minor loss factor. The total scattering is the second major loss factor and is in fact Rayleigh having a λ−4 dependence, in which the extrinsic scattering loss is due only to waveguide imperfections. This study demonstrates that a stable fluorophosphate glass composition can be prepared using optimized processing technologies, and scattering losses in fibers drawn from this composition can be reduced to those observed in synthetic silica fibers.

Hybrid Pr/sup 3+/-doped fiber amplifier comprising of fluoride and chalcogenide glasses

Summary form only given. We have proposed a novel configuration of Pr/sup 3+/-doped fluoride/chalcogenide glass fibre amplifier which realizes a flat output spectrum and higher output power in the 1290-1330-nm wavelength region.