Gothenburg, Sweden--Researchers at Chalmers University of Technology have demonstrated a phase-sensitive optical amplifier that can amplify light with a link noise-figure improvement of almost 6 dB compared to conventional erbium-doped fiber-amplifier (EDFA)-based links.1 The amplifier enables a reach increase for optical-fiber signals from, for example, 1000 to 4000 km.
By using a phase-sensitive fiber-optic parametric amplifier (PSA), the noise figure was reduced to 1 dB; in contrast, in conventional EDFAs the noise figure is 3 dB at best, resulting in loss of signal integrity. This represents a real advance because it is implemented in a practical way, making it potentially attractive in high-capacity optical-communication systems.
"The amplifier is compatible with any modulation format, with traditional laser transmitters, and can be very broadband, making it compatible with many lasers at different wavelengths," says Peter Andrekson, who developed the low-noise amplifier together with his research group.
Nonlinear optical device
The group has taken advantage of the fact that the refractive index of glass is not constant, but dependent on light intensity in the fiber (in other words, it is optically nonlinear). The new amplifier has theoretical minimum of 0 dB, meaning no noise is added in the amplification process.
"The technology is generic, and scalable to other wavelengths like visible or infrared light, which makes it attractive in areas such as measurements, spectroscopy, laser radar technology and any applications where detection of very weak levels of light is essential," says Andrekson.
REFERENCE:
1. Z. Tong et al., Nature Photonics, Published online 05 June 2011; doi:10.1038/nphoton.2011.79.
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