Department of Electrical and Computer Engineering
Development of all-optical control techniques
using nonlinear fiber effects
Eiji SHIRAKI

Associate Professor, Ph.D.
Email : shiraki@gifu-nct.ac.jp
Research Fields
Keywords

Optical network, Optical device
Optical fiber, ultrashort pulse, Nonlinear optical effect● Research Outline
All-optical control techniques using nonlinear
optical effects in fibers

Pulse trapping and amplification phenomena
in birefringent fibers

In fiber-optic communication, the large-capacity
optical networks are required to respond to theincreasing of the data traffic. For the next-generationfiber-communication systems, it is necessary to develop
ultrafast and wideband optical devices. To use
nonlinear optical phenomena in optical fibers are themost effective methods for the all-optical signal control
techniques due to the high nonlinearity, ultrafast
response speed, wide bandwidth, low loss, andcompatibility with the fiber-based systems.

We investigate the mechanism and characteristics ofthe novel nonlinear fiber phenomena of pulse trapping
and amplification in birefringent fibers bothexperimentally and numerically. Additionally, wedeveloped novel ultrafast all-optical control techniques
using pulse trapping and amplification in birefringent
fibers.

In 2002, the interesting nonlinear fiber phenomenaof “pulse trapping and amplification in birefringent
fibers” were discovered by N. Nishizawa and T. Goto.
The nonlinear fiber phenomena of pulse trapping andamplification in birefringent fibers have been attractive
for the ultrafast all-optical control techniques. As
shown in Fig.1, an ultrashort control pulse traps
ultrashort signal pulse in optical fiber (or twin ultrashortpulses trap each other), and they co-propagate along thefiber. In the propagation along the fiber, the pulse
energy is transferred from one to another. Recently, wedemonstrated pulse trapping of a continuous wave beam
and incoherent light and by ultrashort pulse inbirefringent fibers.
The attractive devices using this novel nonlinear
fiber phenomena can be developed for the nextgeneration ultrafast and wideband fiber-optic
communication systems, light sources, and so on.
Fast

Using the pulse trapping and amplification
phenomena in a standard low-birefringent fiber, aultrafast all-optical signal regenerator have beendeveloped. When the temporal difference between thetwo pulses was varied at the fiber input, the initial
temporal differences are compensated for and theamplified signal pulse was obtained. The output
waveform is a chirp-free, sech2-shaped, ultrashort pulse.
Thus, the regenerator is capable of performing threefunctions in a single fiber simultaneously: amplification,re-shaping, and re-timing. Since pulse trapping andamplification originates from the ultrafast nonlinear
effects of cross-phase modulation, and stimulated
Raman scattering, the wideband and ~1 THz ultrafast
operation can be achieved.
The performances can be improved using
appropriate fibers (highly nonlinear fiber, photonic
crystal fiber, etc.). We expect that the techniques would
be the key to develop devices applied for a large
capacity (next-generation) communication.

Birefringent fiber
Slow

Fast
Signal pulse (λs)

Control pulse (λc)(Pulse trapping and amplification)

Output signal pulse
a. Amplificationb. Temporal overlap
c. Sech2-shape

Slow

Fig. 1. Scheme of pulse trapping and amplification in birefringent fibers.

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