Silica fiber-optic amplifiers

Trivalent europium has been demonstrated to produce a bright red fluorescence, which peaks at about 615 nm in glasses. More recently, europium was successfully incorporated into gel-derived glasses [33,34]. Possible applications include solid-state lasers in the visible and fiber-optic amplifiers. The fluorescence spectra of Eu3+-doped silica is presented in Fig. 5. The 615 nm peak associated with the 5Do transition state is clearly evident, along with three... 

In January 1992. E. Desurvire (Columbia University Center for Telecommunications Research) reported that optical fibers made from silica glass and traces of erbium can amplify light signals when they are energized by infrared radiation. Desurvire developed an efficient radiation source (referred (o as a laser diode chip) that, when integrated into a fiber optic communication system, can increase transmission capacity by a factor of 10(1. 

With an emission at 1.3 /tm, Nd3+ is a potential candidate for optical amplification in the second telecommunication window. However, optical gain remains limited because of amplified spontaneous emission at 1.05 fim and also because of strong ESA at 1.3 /on. This ESA process, which takes place from 4F3/2 to (4G7/2, 2K13/2) and to 4G9/2 as shown in Fig. 5, is so probable that no gain is achieved around 1.3 /tm in silica fibers. In ZBLAN fluoride fibers, gain is achieved at 1.34... 

Optical amplifiers are essential components for the development of high capacity telecommunication networks. Silica fibers are characterized by a low-loss optical window that ranges from 1.2 to 1.7qm, as shown in Figure 4. That window is divided into the ultrashort (XS), short (S), conventional (C) and long (L) bands. The first two bands are centered at 1.3 and 1.47 qm, while the C- and L-bands are equal to 1530-1565 run and 1565-1625 nm, respectively. Amplification in the C- and L-bands is commonly achieved with Er +-doped silica fibers. On the other hand, amplification at 1.47 qm and 1.3 qm with Tm + and Pr + ions requires the use of materials with lower phonon energy than silica. High gain optical amplification was demonstrated in the XS, S, and C, telecommunication windows with rare earth-doped... 

Er3+-doped silica glass has tremendous potential as fiber amplifiers in long-distance, high bit rate optical communication systems [30]. The 1.55 pm emission of Er3+ can be pumped at 0.98 and 1.45 pm by laser diodes. Intense interest... 

Transmission properties. The recent interest in erbium- (Er +-)doped fiber amplifiers (EDFA) originates from the recognized fact that the optical fiber transmission windows for silica or fluoride glasses (fig. 34) are in tune with the wavelengths of the two Er + transitions I13/2 I15/2 at 1.5 pm, and Ii 1/2 I13/2 at 2.7 pm. 

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