Aug 1, 2002 - to WDM transmission systems. We installed the hybrid FRA as a pre- amplifier downstream of an 80 km standard SMF. Eight signal channels.
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The NFs in the flattened gain bands were < 7.8 dB without GEQ and cU.3dB with GEQ. We denote the minimum and maximum gains as G,,, and C,,.,, thc difference betwcen the two gains as AG = G,, - G i n , and the relative gain flatness as AC-, = AGIGmin. . The relative gain flatness of the amp6fier without GEQ was 52%. This relative gain flatness AG.,., can be comvared with that of the tellurite Raman amplifier described in [ 6 ] , which was 100% where G,,,= l 0 d B and G,,,,=20 dB. Therefore, the gain flatness with the hybrid telluritc/silica Raman amplifier was significantly better than with the simde tellurite Raman amdifier. We measured &e bit error rates (BER) in an IM-DD transmission system with the hybrid FRA to c o n h the applicability of the amplifier to WDM transmission systems. We installed the hybrid FRA as a preamplifier downstream of an 80 km standard SMF. Eight signal channels were arranged on the ITU 100 GHz grid in some pan of the amplifier gain band. For simdicity, we modulated the eight . signals - simultaneously by using a'LiNbO, intensity modulator at IOGbit/s with a 2" - I long PRBS NRZ format. The signals were then amplified by a thulium-doped fibre amplifier, a C-band EDFA, or an L-band EDFA, and launched into the SMF. The signals amplified by the hybrid FRA were detected by a pin photo diode through an arrayed waveguide grating in an optical receiver. A single signal channel transmission experiment was also undertaken IO clarify the basic BER performance of the amplifier. for a Fig. 30 shows the received signal power spectra at BER = single signal channel transmission. The received signal power was defmed at thepin photo diode input. The signal power launched into the hybrid FRA was set at -23 dBm. Error free operation with a BER of
