Toshio Kurashima

Low distortion slow light in flat Brillouin gain spectrum by using optical frequency comb.

We present a novel method for realizing a slow light with a broadband flat Brillouin gain and low distortion by using an optical frequency comb. We obtained a pump light consisting of 20 discrete line spectra using an optical frequency comb generation technique and a flat SBS gain with a 200 MHz bandwidth. We have realized a large relative pulse delay of 2.46 while suppressing the broadening factor to less than 1.19 for a pulse with a duration of 5.44 ns.

Ultra-Broadband Mode Conversion With Acousto-Optic Coupling in Hole-Assisted Fiber

This paper describes the acousto-optic properties of hole-assisted fibers (HAFs) numerically and experimentally. We show that the HAF beat length between the guided and first higher-order modes has small wavelength dependence compared with that of the single mode fiber and so we can achieve broadband acousto-optic coupling. Ultra-broadband acousto-optic coupling is realized by using a HAF with flattened beat length characteristics. The coupling bandwidth reaches 120 nm, and can be controlled by designing the air hole structure.

SBS Suppressed Fiber With Hole-Assisted Structure

This paper describes a fiber design that incorporates a hole-assisted structure for suppressing stimulated Brillouin scattering (SBS). The proposed hole-assisted fibers (HAFs) have a simple structure with a low relative index difference and/or a small core radius. We suppress the SBS by extending the optical field into the cladding region, which reduces the overlap between a lightwave and an acoustic wave both in the fundamental mode. The bending loss remains low because of the optical field confinement provided by the air holes. We discuss the impact of the core profile on the SBS gain spectrum and show numerically a 13.5 dB improvement in the SBS threshold with both a low SBS gain and a large effective area. Moreover, we show that we can realize SBS suppressed HAF with a low bending loss and almost the same mode field diameter as SSMF by designing the air hole structure. Finally, we experimentally confirm the SBS suppression effect by using the fabricated HAF.

Relationship between optical wiring conditions and MPI degradation

Optical wiring conditions are investigated numerically and experimentally with a viewpoint of MPI induced transmission performance degradation. We reveal the impact of the interval of the bending portion on MPI degradation for the first time.

Distributed Sensing Techniques Using Brillouin Scattering

This paper describes a 1.55/l .65 ?m B-OTDR for measuring both the strain and optical fiber loss distributions in 30- and 100- km optical fiber, and discusses the simultaneous measurement of ?B and ?B for separating strain and temperature.

Side-view based angle alignment technique for multi-core fiber

Precise rotational angle alignment to splice multi-core fiber is successfully achieved by analyzing the symmetricity of side view contrast. Our proposed technique potentially enables the automatic passive low loss fusion splicing of multi-core fiber.

Mechanical Splice Characteristics of a Hole-Assisted Fiber

The mechanical splice characteristics of a single-mode hole-assisted fiber (SM-HAF) are investigated both numerically and experimentally. Mode-coupling theory is used to investigate the mechanical splice loss characteristic of the HAF. We introduced an air filling fraction and a \bm V-parameter to allow us to consider an HAF with arbitrary structural parameters. We derive the optimum conditions (e.g., refractive index and temperature coefficient) of a solid-type refractive index matching material to realize good splice and return loss characteristics simultaneously. The validity of the derived conditions is investigated experimentally. Finally, we confirm that we can achieve comparable splice characteristics to those of conventional single-mode fiber splices by using the optimized refractive index matching material independent of the structural parameters of the SM-HAF.

MPI characteristics of HAF based optical cord with MFD unmatched launching and impact of sweep fusion splicing

Single-mode hole-assisted-fibre (HAF) based optical cord reveals no multipath interference (MPI) degradation independent of the existence of a mode-field diameter mismatch. Moreover, sweep fusion splicing effectively reduces MPI even if the HAF has extremely strong confinement.

Fiber design for SBS suppression by using hole-assisted structure

We propose a simple fiber design with a hole-assisted structure for suppressing SBS. We experimentally realize a 7.0 dB improvement in the SBS threshold compared with SSMF, and numerically show a 13.5 dB improvement by profile optimization.

High Capacity WDM Transmission in 1.0 μm Band over Low Loss PCF Using Supercontinuum Source

We show the possibility of Tb/s WDM transmission at 1.0 μm over PCF using a supercontinuum. The first 1.0 μm WDM transmission was obtained using a supercontinuum with a -10 dB bandwidth of 2.8 THz.