Shaking it up

Abstract

Researchers at the University of Notre Dame in the US have developed an Er/Yb co-doped compound semiconductor native oxide that significantly enhances laser absorption efficiency, thus increasing the viability of realising a low-cost, monolithically-integrated wavelength amplifier with on-board pump laser source.Wavelength division multiplexing is a widely used technology in long haul optical communications networks where as many as 100 different closely spaced channels of data are simultaneously transmitted in an optical fibre, with each channel sent by a slightly different wavelength laser. Fibre amplifiers are used to amplify all of these signals simultaneously within the fibre all optically, so that optical-electrical-optical conversions requiring a number of components are unnecessary. A pump laser excites doping atoms which can then provide gain (optical amplification) for the signals traveling in the fibre, boosting their power as much as 1000 times. These signals are photons generated by single wavelength lasers, all spaced 50-100 GHz apart at wavelengths around ∼1550 nm.