The Outside Vapor Deposition Method of Fabricating Optical Waveguide Fibers

The outside vapor deposition (OVD) process for fabricating high performance glass optical waveguide fibers is reviewed. Starting metal halide chemicals, porous soot preform fabrication, sintering steps, and fiber drawing are discussed. Preform target size and its effect in obtaining deposition rates to 4 g/min is presented. Data comparisons of OVD fiber performance with other vapor deposited techniques are presented for attenuation, hydroxyl content, and strength (0.7 GPa / M/sup 2/ for 49.5 km of fiber). Single-mode fiber results including excellent geometric concentricity are also discussed.     

PCVD单模光纤的均匀性研究

研究了用等离子体化学汽相沉积工艺(PCVD)制备单模光纤的均匀性问题。首先,给出了沿光纤轴向各段的衰减系数、模场直径、截止波长和几何尺寸的测量结果,然后,分别从化学汽相沉积原理和预制棒成丝流变学原理两个方面分析了熔炼和拉丝工艺对光纤均匀性的影响,进而提出了改善单模光纤均匀性的方法。本文的研究结果对制造优质单模光纤具有一定的指导作用。     

Hybrid technology for large SM fiber performs

A hybrid technology for the preparation of standard and dispersion-modified single-mode (SM) fibers is discussed. Only the most important central region of the fibers is prepared by plasma chemical vapor deposition (PCVD) techniques. The optical cladding is as a high-purity jacket tube using the normal rod-in-tube obtained from low-cost shaping and sintering technologies. Due to in situ plasma etching, no disturbance is caused by the interfaces. Low attenuation is achieved with less than 5% of the fiber volume consisting of PCVD core region. The hybrid technology allows economic mass production of preforms containing more than 300 km of fiber     

Optical time-domain reflectometry (OTDR) of diameter modulations insingle mode fibers

The influence of several types of diameter variations on the attenuation and on the optical time-domain reflectometry (OTDR) traces of specially prepared depressed cladding SM (single-mode) fibers is experimentally investigated. Depressed-cladding SM fibers have been prepared by the low-pressure plasma-induced chemical vapor deposition (PCVD) process. The core consists of GeO₂-doped SiO₂ and the cladding region of fluorine-doped silica. During drawing, the diameter of the fiber is controlled within ±0.3 μm for slow perturbations by adjusting the drawing speed (Anritsu M501A). Variations of the core diameter have been accomplished by changing the set point of the fiber diameter control. Core diameter changes give rise to steps or deviations in slope of the OTDR power trace of about 0.3 dB/μm. No indication of additional attenuation due to axial fiber parameter variations has been found up to core diameter changes of 12 μm/m, despite severe distortions of the OTDR traces     

Design and fabrication of high gain-efficiency erbium-doped fiberamplifiers

The gain efficiency of a fully optimized erbium-doped fiber amplifier (EDFA) is calculated as a function of the fiber numerical aperture and dopant confinement in the core and is shown to agree well with experimental data. A gain efficiency of 8.9 dB/mW is demonstrated. This is the best reported value to date for modified chemical vapor deposition (MCVD) fibers. In addition, the detrimental effect of pump and signal background losses on the optimal gain efficiency is considered in detail     

Infrared optical fibers with vapor-deposited cladding layer

Core-cladding structures constructed for KRS-5 polycrystalline and As₂S₃ glass infrared fibers by means of vapor deposition are discussed. In order to obtain high-numerical-aperture fibers, KRS-6 and AsS₃, respectively, have been used as cladding materials. A CO₂ laser beam of 15-20 W has been successfully transmitted through the KRS-5 fiber. For the As₂S₃ fiber an absorption loss due to Teflon coating has been reduced, and a loss of 0.13 dB/m has been achieved     

Dispersion compensation optical fiber modules for 40 Gbps WDM communication systems

Dispersion compensation was originally proposed to equalize pulse distortion.With the development of wavelength division multiplexing (WDM) techniques for large capacity optical communication systems,dispersion compensation technologies have been applied into the field.Fiber-based dispersion compensation is an attractive technology for upgrading WDM communication systems because of its dispersion characteristics and good compatibility with transmission optical fibers.Dispersion compensation fibers and the modules are promising technologies,so they have been receiving more and more attention in recent years.In this work,high performance dispersion compensation fiber modules (DCFMs) were developed and applied for the 40 Giga bit-rate systems.First,the design optimization of the dispersion optical fibers was carried out.In theory,the better the refractive index profile is,the larger the negative dispersion we could obtain and the higher the figure of merit (FOM) for the dispersion optical fiber is.Then we manufactured the fiber by using the plasma chemical vapor deposition (PCVD) process of independent intellectual property rights,and a high performance dispersion optical fiber was fabricated.Dispersion compensation fiber modules are made with the dispersion compensating fibers (DCFs) and pigtail fibers at both ends of the DCFs to connect with the transmission fibers.The DCFMs present the following superior characteristics:low insertion loss (IL),low polarization mode dispersion,good matched dispersion for transmission fibers,low nonlinearity,and good stability for environmental variation.The DCFMs have the functions of dispersion compensation and slope compensation in the wavelength range of 1525 to 1625nm.The experiments showed that the dispersion compensation modules (DCMs) met the requirements of the GR-1221-CORE,GR-2854-CORE,and GR-63-CORE standards.The residual dispersions of the G.652 transmission lines compensated for by the DCM in the C-band are less than 3.0ps/nm,and the dispersion slopes are also compensated for by 100%.With the DCFMs,the 8×80km unidirectional transmission experiments in the 48-channel 40Gbps WDM communication system was successfully made,and the results showed that the channel cost was smaller than 1.20dB,without any bit error.     

Fabrication and characterization of Yb3+:Er3+phosphosilicate fibers for lasers

Fabrication process of efficient Yb³⁺,Er³⁺ codoped phosphosilicate fibers by modified chemical vapor deposition (MCVD) combined with the solution doping technique is studied in detail. We show that the process can be adapted to incorporate low viscosity phosphate glass and some important issues in the fabrication process are discussed. These include the sensitive presintering pass. We also report on the fabrication of a low loss all-glass double clad Yb³⁺:Er³⁺ codoped fiber. We explain how we evaluate the fibers and discuss the effect of the ytterbium to erbium concentration ratio on the laser characteristics. Finally, we present results of some investigations into the mechanisms which can affect the efficiency of the lasers, and show that the detrimental up-conversion from the metastable level of the erbium ions is dramatically reduced by the presence of the ytterbium ions     

Germania-based core optical fibers

Germania-glass-based core silica glass cladding single-mode fibers (/spl Delta/n up to 0.143) with a minimum loss of 20 dB/km at 1.9 /spl mu/m were fabricated by the modified chemical vapor deposition (MCVD) method. The fibers exhibit strong photorefractivity with the type-IIa-induced refractive-index modulation of 2/spl times/10/sup -3/. The Raman gain of 300 to 59 dB/(km/spl middot/W) was determined at 1.07 to 1.6 /spl mu/m, respectively, in a 75 mol.% GeO/sub 2/ core fiber. Only 3 m of such fibers are enough for the creation of a 10-W Raman laser at 1.12 /spl mu/m with a 13-W pump at 1.07 /spl mu/m. Raman generation in optical fiber at a wavelength of 2.2 /spl mu/m was obtained for the first time.     

Materials and processes for preform fabrication—Modified chemical vapor deposition and plasma chemical vapor deposition

This paper summarizes recent achievements and current directions of process developments for making optical fibers by modified chemical vapor deposition and plasma deposition.     

Analysis of dispersion in the nano-InP doped fiber

We propose that nanomaterials are used for fibers.A novel nano-InP doped fiber has been fabricated by the method of modified chemical vapor deposition(MCVD).It has been measured that the doping concentration of phosphorus element is 0.1%.The relationship between refractive index and the wavelength is obtained by fitting experimental data to Sellmeier equation.Dispersion of the fiber has been calculated in the wavelength range of 1.2-1.6 μm.As the wavelength varies from 1.20 μm to 1.60 μm,dispersion paramete...     

Laser enhancement of thermophoretic deposition processes

Axial CO2laser radiation has been shown to have a significant influence in modifying the deposition of silicon dioxide in the modified chemical vapor deposition (MCVD) fiber preform process. Experiments on soot deposition with a stationary burner have shown a doubling of both the rate of deposition and the deposition efficiency.     

Fundamental mode size and bend sensitivity of graded and step-index single-mode fibers with zero-dispersion near 1.55 µm

Single-mode fibers, for near 1.55-μm operating system wavelength with triangular (alpha = 1), parabolic (alpha = 2), and step-index (alpha=infty) profiles were fabricated by the modified chemical vapor deposition (MCVD) technique. Optical transmission losses under zero-tension and with the basket weave under 10, 40, and 70 gm tensions were measured, respectively. Fundamental mode size was obtained as a function of wavelength by using the transverse offset technique. The triangular-profile fiber shows lower loss (≃0.25 dB/km at 1.55μm) under zero-tension and a larger spot size than the other fibers. However, the basket weave test showed the triangular-profile fiber incurred higher loss with tension than the other profiles.     

Erbium-Doped Fibers Based on Cesium–Silicate Glasses

Using modified chemical vapor deposition and solution doping techniques, erbium-doped fibers (EDFs) were prepared based on cesium–silicate glasses. The possibility of manufacturing high-concentration (1–13 wt%) EDFs was shown, and a fiber structure was realized by means of direct doping of cesium–silicate glass with erbium ions. The optical, fluorescence, and gain properties of prepared samples were examined. A maximum gain of 25 dB at 1538 nm was achieved in the fiber at an optimum length of 30 cm at a pump power of 50 mW at 979 nm.     

一种新型掺半导体纳米微粒光纤

将纳米技术应用于光纤技术,通过改进的化学气相沉积法(MCVD),制成了一种新型的掺半导体纳米InP微粒的新结构光纤.经测试,该光纤中掺杂InP质量分数约为0.1%,且具有良好的波导通光性能.根据扫描电镜(SEM)下观察到的光纤截面微结构形貌,通过有限元法(FEM)进行数值分析,得到该光纤的有效截面面积约为10.01 μm2,从而进一步得到该光纤的非线性系数约为10.53 W-1·km-1.证实了此种光纤较普通光纤具有较高的非线性.     

Materials and processes for fiber preform fabrication—Vapor-phase axial deposition

The vapor-phase axial deposition (VAD) process was developed to realize continuous fabrication of high-silica fiber preforms. This process could be used to fabricate various kinds of optical fibers such as graded-index, single-mode, and high NA fibers. Transmission characteristics of these VAD fibers have improved to the level almost comparable to the best values attained by the MCVD process. The VAD process has excellent prospects as an economical means to produce long-length fibers with good transmission characteristics.     

轴向气相沉积法F掺杂对玻璃的腐蚀作用

利用轴向气相沉积法制备高掺F光纤预制棒过程中,CF4作为掺F源,在高温状态下,对所接触到的玻璃器皿产生腐蚀作用。本文研究了CF4气体在沉积过程对喷灯的腐蚀规律;CF4气体在玻璃化过程中对玻璃化炉的腐蚀。     

Dispersion-flattened single-mode fibers prepared with PCVD: Performance, limitations, design optimization

The first test on the reproducibility of the preparation of dispersion-flattened single-mode (DFSM) fibers is reported in this paper. Dispersion of less than 2 ps/(nm . km) between 1.32 and 1.6μm was achieved for a set of 15 fibers (31 km), with identical diameter prepared by means of the low pressure plasma-induced chemical vapor deposition (PVCD) process. Investigations on the influence of the substrate tube geometry, the "rod-in-tube" technique, and refractive index distortions on dispersion are presented. CAD optimized index profiles are discussed.     

Developments in optical waveguide fabrication by the outside vapor deposition process

Improvements in optical fiber fabrication made over the last two years using the outside vapor deposition (OVD) process are reported. Advances have been made in the areas of optical and mechanical performance for existing products, dopant changes, and single-mode fiber designs. A multimode fiber having no P2O5in the core has been demonstrated which also exhibits uniform forward and cutback bandwidth-length dependence and improved resistance to the effects of hydrogen. Data is also presented on a dispersion-shifted single-mode fiber made using the segmented core approach which has recently been put into production.     

Measurements and calculations of the LP01 intensity ofSM fibers far off the core

Transverse offset measurements with a dynamic range of 10⁶ were performed to determine the autocorrelation of the intensity as a function of the fiber's radial coordinate between 0 and 30 μm. Various matched-cladding, depressed-cladding, and dispersion-flattened single-mode fibers were investigated at wavelengths of 1150, 1300, and 1550 nm. The experimental results are compared to analytical approximations and numerical calculations. Satisfactory agreement for all types of fibers is found if the refractive-index profiles are evaluated carefully and if the wave equation is solved numerically. The results are useful for a realistic estimation of the influence of impurities and imperfections of the substrate tubes used for the plasma chemical vapor deposition (PCVD) process on the attenuation of the fibers