通过初步传输实验,证实了采用低损耗单模纤维与精心设计的镓铝砷激光器相结合的办法,在八百兆比特速率时,中继间隔可长达7.3公里。用信号电流迭加在高于阈值的直流偏置电流上来调制激光器。在以消光比恶化为代价的前提下,这种调制方案避免激光的频谱展宽。所测到的与计算出的误码率特性曲线间的误差约为13dB。误差的主要部份10dB是由于消光比恶化引起的。 Preliminary transmission experiments confirmed the use of low-loss single-mode fiber with a well-designed GaAlAs laser combined with a repeater interval of up to 7.3 km at a rate of eight hundred megabits. The laser is modulated by superimposing the signal current on a DC bias current above a threshold. This modulation scheme avoids laser spectrum broadening at the expense of extinction ratio deterioration. The error between the measured and calculated bit error rate characteristics is about 13 dB. The main part of the error, 10 dB, is due to extinction ratio deterioration.