We report an investigation of design, fabrication and measurement for photonic crystal fibers developed by YOFC in
three years. The development status of PCFs and their applications are synoptically investigated. In the part of
fabrication process, a technology route of PCF fabrication are reviewed, and the process principle, process control and
realization method are introduced mainly, related to process bottlenecks. Based on different PCFs designed respectively
by Beam-Propagation Method, Plane-Wave Expansion Method or FDTD and the above fabrication process, we probed
into and realized some kinds of PCF samples. The structure parameters, cross-section morphologies, attenuation and
dispersion properties for PCF samples are respectively investigated. We also debate upon the potential application of
With the rapid development and widely used of fiber grating, the demand of high quality
photosensitive fiber has increase greatly. Based on the plasma chemical vapor deposition (PCVD) process,
the Ge/F co-doped photosensitive fiber was developed. Through analyze the fiber's photosensitivity,
study the fiber's photosensitivity influenced by the doping process. The data indicate that the high F
doped (5%) Ge/F photosensitive fiber's grating has the 80% reflectivity, much lower than the low F
doped(1%) Ge/F photosensitive fiber's 94%. The F doped content can influence the fiber's photosensitivity distinctly.
Single mode fiber (SMF) has been used widely in local and access network since the early 1980's. Fiber loss reduction
will accelerate the construction of various transmission systems with longer repeater spacing. It has been reported that
the transmission loss in SMF increases due to residual stress, which is caused by viscosity mismatch between the core
and cladding material. The idea of viscosity matching is to match the viscosity of core and cladding doping to minimize
the viscosity difference on the cross-section of the fiber or preform. The dopant concentrations can be chosen so that the
viscosity of core and the cladding are equal in ideal step index fiber. However, all the reported viscosity-matching
design is based on single dopant, for example, only GeO2 is doped in the central core and only F in the cladding. In this
paper, optical loss reduction through viscosity-matched design for the SMF with GeO2-F codoped silica core and
cladding is described. The impact of viscosity-matching on optical loss of silica-based single-mode fiber has been
investigated in detail theoretically and experimentally based on PCVD fiber. For PCVD optical fiber, F is introduced in
core is to reduce the water peak. Single mode optical fiber with low attenuation fabricated by PCVD process can be
gotten through viscosity-matching design between core and cladding. Viscosity-matching can reduce the sensitivity of
attenuation to drawing tension. The model for estimating the viscosity matching has been deduced, which can not only
be used for conventional SMF but also for the fiber with arbitrary index profile.
Quartz optical fiber or preform is composed of core and cladding with different refractive index (RI). Their compositions are different from the core to cladding in order to acquire desired RI profile. The physical properties from core to cladding are different, such as thermal expansion coefficients, thermal capacity and glass transition temperatures, which have much effect on the properties of optical fiber. The material composition and structure in PCVD single mode (SM) fiber was introduced in this paper. The composition of PCVD SM fiber was SiO2-GeO2-F-(Cl). F acted as a water-getter to reduce water peak besides lowering the RI of quartz glass and GeO2-F co-deposition was adopted in PCVD fiber. The functional graded material (FGM) design in PCVD SM fiber, which can reduce the attenuation, PMD, splicing loss and improve microbending resistance, was analyzed and discussed.
In this paper, a novel fiber manufacturing process based on PCVD is introduced. The fiber drawing length per preform can reach more than 5,000 km and the cost is lower. The fiber shows better optical and geometrical properties. Such large size preform combines the advantages of PCVD process for high quality and OVD process for low cost. This PCVD RIC process will be helpful for increasing the ability of inside vapor deposition process.
Low water peak single mode fiber (LWP-SMF) fabricated by PCVD based process has been described. Based on the whole process of PCVD fiber, the hydroxyl contamination and its sources are as follows: (1) raw material, such as SiCl4, GeCl4, O2, C2F6, substrate tube and jacket tube; (2) leakage of the system including PCVD and collapsar; (3) surface contamination. The latter purification of deposited glass is extremely difficult, so the most effective solution is prevention. The hydroxyl contamination prevention and elimination measures, such as purity improvement of raw material, online purification during PCVD, surface absorption reduction and dilution effect with large preform, which are the key factors for LWP-SMF fabrication by PCVD based process, are revealed. Large scale production has revealed that LWP-SMF can be fabricated by PCVD based process combined with above mentioned process innovation. PCVD LWP-SMF complies with or exceeds the ITU recommendation G.652 (C and D) and IEC 6093-2-50 type B 1.3 optical fiber specification. With further development of high purity raw material, machine-airproof improvement and larger preform (above 150mm) combined with material composition and structure optimization in optical fiber or preform, high performance PCVD LWP-SMF with lower water peak or even zero-OH performance will be achieved. Besides, other type of optical fiber with low water peak, such as G.653, G.655 and G.656, can also be made with the advanced PCVD based process.
A kind of new single mode optical waveguide has been designed and it is prepared by PCVD process. The design and the characteristics of the optical waveguide are studied and discussed in the paper. The waveguide structure of multi-core layers is adopted. Two types of designs, concept-a and concept-b are analyzed and compared. The characteristics of the optical waveguide based on concept-b are very excellent. It is a kind of non-zero dispersion shift optical fiber (NZ-DSF). The zero dispersion wavelength(λ0) is about 1390nm and the absolute value of dispersion from 1200nm to 1625nm is lower than 14 ps/(nm×km). The typical mode field diameter of this optical waveguide is 9.1 um. However, its cut-off wavelength(λc) is not higher than 1200nm and it is much lower than that of existing non-zero dispersion shift optical waveguide, but the bending resistance property of the optical waveguide is excellent. The Macro-bending loss at 1625nm is about 0.019 dB/turn when the spindle diameter is 32mm. Besides, it has low attenuation in the broad spectrum; especially the water peak is lower than 0.34 dB/km. It has super-broad spectrum, from 1200nm to 1625nm, transmission capability as single mode optical waveguide, so it can be used in the high transmission speed DWDM system.