一、引言发展陆地长途干线和海底光缆通信的关键是采用长波长单模光纤通信系统。为了降低话路成本和提高可靠性,把增大通信容量和加长中继距离作为单位设计的主要目标。1.3～1.6μm长波长范围低损耗单模光纤的研制成功,为实现超大容量和长距离光纤通信系统提供了可能性。石英光纤的损耗与色散特性如图1所示。石英光纤在1.3μm波长下的色散最小(接近于零),传输损耗约为0.5dB/κm;在1.55μm波长下具有最低的传输损耗,约为0.2dB/κm,但却伴随有15～18ps/nm/κm的残余色散。通常,半导体激光器具有法布里-珀罗(F-P)型 I. INTRODUCTION The key to the development of land long-distance trunk and submarine optical cable communication is the use of long-wavelength single-mode optical fiber communication system. In order to reduce the cost and improve the reliability of the road, to increase the communication capacity and extend the relay distance as the main goal of the unit design. The successful development of low loss single-mode fiber with 1.3-1.6μm long-wavelength range offers the possibility to realize ultra-large capacity and long-distance optical fiber communication system. Quartz fiber loss and dispersion characteristics shown in Figure 1. Quartz fiber has the least dispersion (close to zero) at 1.3μm wavelength with a transmission loss of about 0.5dB / κm; the lowest transmission loss at 1.55μm with a wavelength of about 0.2dB / κm but with 15 ~ 18ps / nm / κm residual dispersion. In general, semiconductor lasers have a Fabry-Perot (F-P) type