Tomonori Kashiwada

Silica-based functional fibers with enhanced nonlinearity and their applications

Silica-based optical fibers are now being used in various applications which utilize nonlinear effects in fiber. In addition to enhancing nonlinearity of optical fibers, tailoring chromatic dispersion is one of the important design issues in such applications. Highly nonlinear dispersion-shifted fibers have been developed, and a very compact wavelength converter module has been demonstrated by using the fiber. Dispersion-flattened and dispersion-decreasing fibers have also been proved to be highly effective for supercontinuum generation.

High-performance dispersion-compensating fibers

Abstract An optimum fiber structure for a practical dispersion-compensating fiber (DCF) has been explored theoretically and experimentally, taking dispersion, attenuation, bending loss characteristics, polarization mode dispersion, and nonlinear effects into account. A high figure of merit (FOM) of 280 ps/nm/dB has been successfully achieved with a simple matched cladding design. Furthermore, it was confirmed that the optimized structure with enhanced FOM also benefits self-phase modulation (SPM) suppression.

Broadband dispersion compensating module considering its attenuation spectrum behaviour for WDM system

Dispersion-compensating module capable of flattening the dispersion spectrum in 80 km of single mode fibre (SMF) was successfully developed while realizing attenuation variance within 0.35 dB/module in 1530 nm to 1570 nm and attenuation fluctuation <0.1 dB/module in -5/spl deg/C to 50/spl deg/C.

Novel dispersion compensating fiber with fluorine-doped cladding for simultaneous realization of high dispersion compensation efficiency and low attenuation

Fluorine-doped cladding with a Delta- of -0.2% was employed for the dispersion compensation fiber with triple-cladding structure, which successfully realized the dispersion less than -300 ps/km/nm while keeping a figure of merit higher than 350 ps/nm/dB

Low Noise Figure Erbium-Doped Fiber Amplifiers with Gain Adjustment by Pump Power Control

Erbium-doped fiber amplifiers (EDFAs) are expected to be used in a broad range of applications. One of the applications of great interest is line amplifiers in long distance communication systems(1) Such line amplifiers are generally characterized by moderate signal gain and moderate output signal power. Noise figure (NF) of those amplifiers should be kept as low as possible.

Gain-Flattened Hybrid Silica-Based Er-Doped Fiber Amlifiers Designed for More Than 25nm-Bandwidth without Gain Equalizers

Without gain equalizers, newly-designed hybid silica-based EDFAs exhibit relative gainnon-uniformity as small as 5.8% over 2Snm-bandwidth , which is comparable to those of fluoride-based EDFAs.

Erbium-Doped Extremely High-dn Single-Mode Fibers

An erbium-doped single-mode fiber with Δn( ESI ) of 3.5 % was fabricated, and the gain coefficient of 5.4 dB/mW was obtained. Its high normal dispersion of -100 ps/km/nm is useful for a dispersion compensator.