Penalty-free dispersion-managed soliton transmission over a 100-km low-loss PCF

A long photonic-crystal fiber (PCF) with a low loss was successfully fabricated by first preparing a large pure silica glass preform. The fiber is 100 km long and has a low loss of 0.3 dB/km at 1550 nm. The fiber has a Rayleigh scattering coefficient of 0.85 dB/(km/spl middot//spl mu/m/sup 4/), which is the lowest value ever reported in a PCF. Using this fiber, the first penalty-free dispersion-managed soliton transmission at 10 Gb/s was achieved in a PCF.     

The Design and Fabrication of Monomode Optical Fiber

The design of monomode fibers is discussed in the context of optimizing fiber loss and dispersion simultaneously, with reference to the materials choices and limitations to preform and fiber fabrication by the MCVD technique. Two classes of monomode structure-matched cladding and depressed cladding-are considered. Ultralow attenuation has been achieved reproducibly in both classes of fiber. The control of fiber geometry and dispersion is also discussed. Matched cladding fiber suitable for systems operating at both 1.3 and 1.55 µm has been studied and mean losses of 0.45 dB/km at 1.3 µm and 0.28 dB/km at 1.55 µm have been achieved for a total of 130 km. The behavior of depressed cladding fiber is compared with predictions from the theory of propagation in W fibers. Depressed cladding fiber with stable guidance has been demonstrated with attenuation of 0.37 dB/km at 1.3 µm and 0.21 dB/km at 1.55 µm.     

Transmission loss characteristics of fluoride glass single-mode fibre

The transmission loss spectrum of a fluoride glass single-mode fibre as obtained with a new preform fabrication technique is shown. It is clearly confirmed on the loss spectrum that the obtained fibre is a single-mode waveguide in the minimum loss wavelength range (2?4 ?m). The minimum loss of this fibre is 8.5 dB/km at 2.2 ?m and the OH excess loss is 15dB/km at 2.85 ?m. This fabrication technique is effective in eliminating OH contamination.     

Ultimately low OH content v.a.d. optical fibres

Ultimately low OH content optical fibres with 1.2% refractive-index difference and 80 ?m core diameter have been successfully obtained by dehydrating a v.a.d.-made porous preform under optimised conditions. The loss increase at 1.39 ?m due to residual OH ions was only 0.04 dB/km. Accordingly, the measured attenuation curve can be resolved into contribution from the intrinsic loss mechanism with the additional low waveguide imperfection loss.     

26 km-long polarisation-maintaining optical fibre

The letter describes the development of a long-length and large-diameter preform for polarisation-maintaining optical fibres. The preform was 470 mm in length and 48 mm in diameter. As a result, a 26 km-long PANDA fibre is developed. This fibre achieves crosstalk of ?22 dB, corresponding to h = 2.4 × 10-7m-1 and a transmission loss of 0.3 dB/km at a wavelength of 1.56 ?m. These fibres will be useful for future high-speed and medium-span coherent optical communications.     

Large graded-index preforms fabricated by high-rate VAD

A large preform for 220 km of fibre was fabricated with the vapour-phase axial deposition (VAD) method. The deposition rate for the core was 1.7 g/min. Optical fibre drawn from a part of the preform had optical attenuation of 0.58 dB/km and bandwidth 500 MHz km0.9 at a wavelength of 1.3 ?m.     

Fabrication of fluoride glass single-mode fibers

Single-mode optical fibers are obtained using ZrF4-based fluoride glasses. The fibers are drawn from a preform and jacketing tube. The preform with cladding/core ratio of 5.1 is made by using a built-in casting method. The cutoff wavelength of the fiber is experimentally determined to be 2.7 μm by bending loss measurement. Minimum transmission loss of the obtained fiber is 160 dB/km at a wavelength of 3.28 μm. TheV-value at this wavelength is estimated to be 2.03 from the core diameter and the refractive index difference.     

Low-OH-content optical fibre fabricated by vapour-phase axial-deposition method

A low-OH-content and long-length optical fibre has been made by the v.a.d. method. The OH content in the rod preform was reduced to about 0.4 p.p.m. utilising the chemical reactions of SOCl2 or CCl4 with OH ions and H2O molecules In the porous glass rod. The minimum loss of the fibre, 20km long, was 1.0±0.1 dB/km at 1.2?m.     

Extruded singlemode, high-nonlinearity, tellurite glass holey fibre

The fabrication of the first singlemode tellurite glass holey fibre produced from an extruded preform is reported. Robust singlemode guidance was observed at 1047 nm in the fabricated small core holey fibre. An effective mode area of 2.6 /spl mu/m/sup 2/ and high effective nonlinearity of 580 W/sup -1/ km/sup -1/ at 1047 nm were predicted. The fibre loss was measured to be 3.5 dB/m at 1050 nm, and 5.8 dB/m at 1550 nm.     

基于液相掺杂的低损耗近等厚芯层掺稀土光纤

过高的纤芯损耗和纤芯折射率非均匀性严重制约了掺稀土光纤在高功率光纤激光器中的应用,提出一种基于液相掺杂的低损耗近等厚芯层掺稀土光纤的工艺方法.结合改良的化学气相沉积(MCVD)溶液掺杂法制备了含有多层疏松层的掺稀土光纤预制棒,理论分析了光纤预制棒缩棒前、后芯层差的变化原理,采用流量递减沉积工艺降低了缩棒后不同芯层之间的...     

Transmission properties of lightguide fibres coated at a line speed of 10 m/s

We report the transmission characteristics of high-speed-coated lightguide fibres; the evaluation is based on a total length of 90 km of single-mode fibre. For this experiment the line speed was varied from 2 to 10 m/s, and each sample length obtained from a preform was ~ 10 km. We found that the average losses of the fibres coated at three different speeds (2, 5 and 10 m/s) are all ~ 0.4 dB/km at 1.32 ?m.     

Fabrication of long lengths of low-loss IR transmitting As40S(60-x)Sex glass fibers

Teflon clad and As₄₀S₆₀ glass clad As₄₀ S₅₅Se₅ fibers transmitting in the 1-6 μm wavelength region have been fabricated in lengths of about 50 m and with minimum losses of 0.098 and 0.65 dB/m, respectively. Short lengths of the Teflon clad fiber possessed a minimum loss of 0.047 dB/m. While current fiber losses are dominated by extrinsic scattering and absorption, the calculated theoretical minimum loss is estimated to be 3.6 dB/km at 5.3 μm and is limited by the contribution from the weak absorption tail. Improvements in the purification and processing of the glasses into the optical fibers are required to reduce the losses further     

Interplay of design parameters and fabrication conditions on the performance of monomode fibers made by MCVD

An apparently undocumented loss mechanism in monomode fibers with germanium doped cores is demonstrated. This loss increases as the fiber drawing temperature and/or the germanium concentration increases. By consideration of this mechanism in the fiber design and fabrication, losses lower than previously reported have been achieved both in fiber with low germanium concentration (0.38 dB/km at 1.3 μm) and in higher doped, dispersion shifted fiber (0.37 dB/km at 1.55μm). The constraints on fiber design as a consequence of this loss mechanism are discussed.     

100 km single mode VAD fibres

100 km single mode fibres with low loss values of 0.3 dB/km at 1.55 ?m and 0.5 dB/km at 1.3 ?m have been made by the VAD method. Swept frequency 6 dB down bandwidths at the two wavelengths were 40 MHz for 100 km length and 800 MHz for 50 km length, respectively.     

Spectral losses of low-OH-content optical fibres

Very-low-OH-content optical fibres consisting of borosilicate-cladding phosphosilicate-core have been produced by a chemical vapour deposition technique. One of the fibres, whose transmission loss was less than 1 dB/km between 0.95 and 1.37 ?m, showed a minimum loss of 0.47 dB/km at 1.2 ?m.     

Frequency characteristics of superconductive coaxial lines

By precise manufacturing methods, 1.6-mm 50-Ω superconductive coaxial lines having few impedance irregularities (0.2 to 0.3 Ω) have been produced. Their attenuation constant at 4.2 K shows a smooth gradual increase upto 12.4 GHz in proportion to frequency. The loss at 1 GHz is 0.7 dB/km for the line using tetra fluoroethylene-hexa fluoropropylene (FEP) and 1.6 dB/km for the line using polyethylene (PE).     

环烯烃共聚物空芯微结构太赫兹光纤的设计与制造

以环烯烃共聚物（cyclic-olefin copolymer,COC）材料为基质,设计、制造了一种空芯多孔包层太赫兹（THz）纤维。利用comsol 软件模拟了芯径为6 mm 的光纤在0.2~1.5 THz 波段的损耗特性,结果表明:在0.85~1.5 THz 波段存在多个低损耗频带,而且在0.85~1.1 THz 波段有低于3 dB/m 的三个窗口;特别是在0.99 THz,损耗达到0.208 dB/m。芯径为3 mm、4.8 mm 和6 mm 的光纤在0.8~1.5 THz 波段的损耗特性对比分析表明:该COC 微结构多孔包层空芯纤维的损耗随着光纤外径的增加而减小。把设计的太赫兹纤维外径放大7 倍达到7 cm,据此设计制造了光纤预制棒成型专用模具。借助热挤出成型方法得到了结构完整、孔洞表面光滑,长度为22 cm 的空芯多孔包层预制棒。利用该实验室独有的微结构光纤拉丝塔,成功获得了微结构保持完好的光纤样品。损耗分析结果表明:6 mm 芯径的光纤样品在1.27 THz 的平均损耗为2.175 dB/m,与该频率的理论损耗（1.95 dB/m）接近。     

低损耗光子晶体光纤的研究进展

损耗是传统光纤和光子晶体光纤得以实用化的重要参量之一,降低损耗是光子晶体光纤制备的首要问题.折射率引导型光子晶体光纤的损耗由1999年的240 dB/km降至0.28 dB/km(1550 nm波长处),光子带隙型光子晶体光纤的损耗也降低到1.2 dB/km(1620 nm波长处).在对比传统石英光纤损耗来源基础上,阐述了光子晶体光纤的损耗机理,并说明了损耗降低的主要途径.     

Single-polarisation operation of highly birefringent bow-tie optical fibres

Experimental results show that bow-tie fibres with high levels of stress-induced birefringence can be operated such that they support only a single linearly polarised mode. Under these conditions the loss of the fibre is 5 dB/km for the guided mode and 55 dB/km for the suppressed mode For short-length operation as a polariser, extinction ratios as high as 50 dB/m have been obtained.     

New low-loss liquid-core fibre waveguide

Low-loss liquid-core fibre-optical waveguides having a transmission loss of 10 dB/km has been made using commercially available glass tubing. The loss is less than 20 dB/km over a wavelength range of greater than 0.8?1.1 ?m, and, at the semiconductor laser wavelength of 0.9 ?m, has a value of 14 dB/km. This is the first low-loss fibre to be made using glass.