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光纤传输的最新研究情况提出了一种可能性,即在80年代末,一根细如发丝的玻璃可以传送约30000路电话,传输容量比现在提高20倍。此外,地处Martlesham的英国电信实验室的研究工作表明,光脉冲的再生间距可提高10倍多,亦即由目前的30km扩大到约400km。相干传输技术将使上述两种发展均成为可能。现在的光纤系统采用带宽高达700GHz的宽谱光信号,而相干系统则采用单一波长、带宽窄的极纯的光,带宽通常为 10—100KHz。这意味着要有一个高精度激光器,其频率稳定误差要优于1×10~9,这在普通光纤系统中是一不太重要的因素。取得窄带宽的方法是选用一个外接到激光基片的一种频率或波长的光谐振腔或滤光器。
Recent research on optical fiber transmission raises the possibility that by the late 1980s a thin, hair-glass glass could carry around 30,000 telephones and deliver 20 times more transmission capacity than it is now. In addition, the research conducted by BT’s laboratory in Martlesham shows that the optical pulse can be regenerated by more than 10 times, expanding from the current 30 km to about 400 km. Coherent transmission technology will make both developments possible. Today’s fiber systems use wide bandwidth optical signals up to 700 GHz, while coherent systems use very pure light with a single wavelength and narrow bandwidth, typically 10-100 kHz. This means having a high precision laser with a frequency stability error of better than 1 × 10 ~ 9 is a less important factor in normal fiber systems. The way to achieve narrow bandwidth is to use an optical resonator or filter of a frequency or wavelength circumscribed to the laser substrate.