Ultralow-Loss Glasses
Ultralow-Loss Glasses
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超低损耗眼镜
DOI：
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发表时间：
1986
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影响因子：
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通讯作者：
M. Lines
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文献类型：
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作者：
M. Lines
光通过玻璃纤维的传播正迅速成为传输音频和视频信息的首选模式，满足更高容量、速度和可靠性的需求是一个始终存在的挑战。目前这一代的光纤是基于熔融石英（SiO2），其光学窗口（在较高频率下的瑞利散射和较低频率下的多声子吸收的竞争衰减机制之间的高透明度区域）在真空波长区域A = 1.5 μ m。光纤通信系统的效率通常被测量为承载能力（每秒可以传输的信息的兆比特数，或者现在甚至是千兆比特数）和光纤长度的乘积，在该光纤长度上，这种脉冲在脉冲扩展（色散）和能量损耗（衰减）方面保持“可恢复”。由于该波长范围内的载波频率超过1014 Hz，目前可达到的最高比特率（1.5 μ m时每秒109比特）受到激光和调制器技术的限制。另一方面，光纤“中继器长度”虽然明显是再生器蒸发器和检测器技术的函数，但主要由光纤材料特性控制。原则上，该中继器长度可以受到色散效应或信号衰减的限制，色散效应最终导致足以引起不可接受的再生误差的脉冲重叠。对于目前正在使用（或准备中）的系统，最大中继器长度约为30 km，其限制由衰减引起。因此，已经开始努力定位具有显著低于二氧化硅的固有衰减潜力的光纤材料（所谓的超低损耗玻璃）。然而，很明显，如果这些材料最终要提供可行的替代方案，它们还必须具有低分散能力
The propagation of light through glass fibers is rapidly becoming the preferred mode of transmitting audio and visual information, and meeting demands for higher capacity, speed, and reliability is an ever-present challenge. The present generation of optic fibers is based on fused silica (Si02) for which the optic window (which is that region of high transparency between the competing attenuation mechanisms of Rayleigh scattering at higher frequencies and multiphonon absorption at lower frequencies) is in the vacuum wavelength region A � 1.5 j.lm. The efficiency of an optic fiber communications system is generally measured as the product of a carrying capacity (the number of megabits, or these days even gigabits, of information that can be transmitted per second) and the length of fiber over which such pulses remain "recover able" in terms of pulse spreading (dispersion) and energy loss (attenu ation). Since the carrier frequency in this wavelength range exceeds 1014 Hz, the highest presently attainable bit-rates (�109 bits per second at 1.5 jlm) are limited by laser and modulator technologies. The fiber "repeater length," on the other hand, though clearly a function of regener ator and detector technologies, is primarily controlled by fiber material characteristics. In principle this repeater length can be limited either by dispersion effects, which lead eventually to pulse overlaps sufficient to cause unac ceptable regeneration errors, or by signal attenuation. For systems presently in service (or in preparation) the maximum repeater length is about 30 km with the limitation caused by attenuation. As a result, efforts have been initiated to locate fiber materials (the so-called ultralow-loss glasses) with a potential for intrinsic attenuation significantly lower than silica. However, it is evident that these materials must also possess low dispersion capabilities if they are eventually to offer a viable alternative