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因制作1.55μm高性能窄光谱带宽激光器存在困难,必须研制普通的多纵模激光器也能在该波长使用的单模光纤。英国电信研究所(BT)最近研制出在1.55μm传输窗口很低损耗,零色散的单模光纤。光纤色散有材料色散和波导色散。经研究,材料色散随波长增加而增加;波导色散则随波长增加有所下降,在二者互相低消的临界点即能获得零色散。BT研制人员们发现,通过增加GeO含量来提高纤芯与包层之间的折射率差,能改善光纤的材料色散;再把纤芯的半径减小到大约2.3μm,能获得较高的波导色散值。以这种方式制作的光纤证明,把零色散移到1.55μm波长没有什么问题。但难以
Because of the difficulty in fabricating a 1.55-μm high-performance narrow-band-width laser, it is necessary to develop a single-mode optical fiber that can also be used by an ordinary multi-longitudinal mode laser and at this wavelength. The British Telecommunications Institute (BT) recently developed a single-mode fiber with very low loss and zero dispersion in a 1.55μm transmission window. Fiber dispersion material dispersion and waveguide dispersion. The dispersion of the material increases with the increase of the wavelength. The dispersion of the waveguide decreases with the increase of the wavelength, and the zero dispersion can be obtained at the critical point of the low elimination of each other. Researchers at BT found that by increasing the GeO content to improve the refractive index difference between the core and the cladding, the dispersion of the material in the optical fiber can be improved, and then the radius of the core is reduced to about 2.3 μm to obtain a higher waveguide Dispersion value. The optical fiber fabricated in this way proves that there is no problem with zero dispersion shifted to a wavelength of 1.55 μm. But difficult