Plasma Deposition Technologies
OPD – Outside Plasma Deposition
Main purpose of Outside Plasma Deposition (OPD) system is deposition of pure or fluorine-doped silica layers on the outside of a target bait. Normally, the target bait is a round or shaped (octagonal, hexagonal, D-shape, square, etc.) quartz rod. Key benefit of OPD technology is that each deposited layer is immediately vitrified into transparent glass. Since each deposited layer is very thin (approx. 5µm), vitrification process occurs at relatively low surface temperature (1450°C – 1700°C). Low vitrification temperature allows high incorporation rate of even very volatile materials such as fluorine. Fabricating glass with OPD allows deposition of layers with fluorine concentrations up to 4 mol%, corresponding to refractive index difference of approximately 0.020 or NA=0.25 with respect to pure silica. Above mentioned characteristics make OPD an ideal technology for production of triple-clad laser fiber preforms or custom-made silica-silica fiber preforms.
PPPS – Preform Polishing Plasma System
Preform Plasma Polishing System (PPPS) uses an atmospheric plasma torch for polishing the outside surface of an optical fiber preforms or other types of quartz rods. Some optical fiber preform preparation processes require special surface treatment where conventional H2/O2 burners cannot be used. PPPS was developed specifically for applications where OH- ions, incorporated on the quartz rod surface during conventional polishing process are an issue. Using a pure oxygen plasma flame significantly mitigates this problem. When fluorine compounds are added to the plasma flame, PPPS can also be used for precise etching process. Customers can use PPPS for control of the preform diameter, thus adjusting the core-to-clad diameter ratio (CCDR) to desired value. Preform diameter can be precisely measured during the process by using Camera Vision System, implemented in OptiFACT control system.
Plasma Deposition Services
Plasma outside deposition process is a key technology for fabrication of special optical fibers, requiring deposition of high fluorine-doped silica layers. Such optical fibers are used in biomedical, aerospace, industrial and defense applications. Plasma enhanced products are not widely available on the global
markets due to the lack of commercial equipment suppliers and required technology knowledge.
Plasil has successfully developed own outside plasma deposition technology and designed OPD plasma deposition system, suitable for small scale fabrication. This system is installed in Plasil’s development lab, in Logatec, Slovenia; and is used for continuous equipment and process development. Specifications of Plasil’s OPD deposition capabilities are presented in below:
Advanced Optical Fiber Preform Fabrication Equipment and Process Solutions for Specialty Optical Fiber Manufacturing
MDS Preform Fabrication System
MDS preform fabrication system is based on versatile and flexible MCVD preform technology. It is suitable for fabrication of wide range of optical fiber preforms and can be combined with a number of add-on devices for special doping (rare earth vapor phase precursor delivery) or advanced processing (FCVD) using a furnace instead of oxyhydrogen burner as heat source. MDS can be adapted to specific customer requirements and is available in different equipment configurations depending on application.
High Temperature Doping System (HTS)
HTS is an add-on system to Bimes MDS preform fabrication processes, using MCVD technology. It was developed to provide high dopant vapor flow for fabrication of preforms with large diameter metal- and rare earth doped cores. HTS is used in fabrication of RE-doped optical fiber preforms for all types and versions of fiber lasers. HTS is a source of high temperature precursor vapors, providing dopants like Al, Yb, Tm, Er, Nd, Sm, and Ce (as well as others) to MCVD (and other) deposition process. Precursors used in HTS are inorganic or organometallic powders. HTS system provides controllable, stable, and repeatable
delivery of vapor to MCVD deposition process for all types of active fibers. HTS is the only system that can provide deposition conditions for large core preforms, improving active fiber homogeneity and draw length. With proper combination of dopants, processes using Bimes MDS and HTS can consistently
produce low NA large core optical fiber designs. Bimes MDS preform fabrication systems, combined with OptiFACT control system, are designed for optimum performance of HTS doping during active preform fabrication process. When used with Bimes FCVD systems, active preform process can be optimized for fast collapse and minimal influence of collapsing condition on preform index profile.
Horizontal Glass Working Lathe (HGL)
HGL glass working lathes in different configurations and sizes are used in substrate tube preparation, welding, stubbing, preform polishing, jacketing and stretching of quartz glass. They are often used for rounding asymmetrically shaped preforms and in preparation of micro-structured preforms for drawing.
Vertical Glass Working Lathe (VGL)
VGL vertical glass working lathe is used for jacketing preforms in vertical position, or for stretching preforms, rods, and silica tubes. Jacketing and other operations in vertical position have specific advantages over horizontal jacketing when very precise core concentricity is required. Vertical glass
working is recommended in jacketing of polarization maintaining fiber preforms, as well as in fabrication of other optical fiber preforms.
GPS Central Gas Purifier
Use of high purity gases in optical fiber preform fabrication is one of the key factors ensuring low losses and proper operation of fabrication equipment. Typical impurities to be removed from reaction gases in preform deposition processes are hydroxyl and any other hydrogen-containing gas, and in draw tower area any oxygen-containing gas. Gas purifiers can be used for other application in semiconductor and industrial processes. GPS is a centralized gas purifier system, using the following purification technologies:
· heated catalyst purifier and regenerating molecular sieve bed drier for O2,
· heated getter purifier and regenerating molecular sieve bed for He,
· regenerating molecular sieve bed drier for nitrogen,
· heated getter (Zr-V-Fe ceramics) for inert gases (He, Ar),
· cartridge getters for special gases (SiF4, SF6, Cl2).
GTS MCVD & OPD Scrubber
GTS gas scrubber is a process waste gas treatment system for effluents from MCVD and plasma deposition equipment. GTS scrubber removes silica particles and pollutants resulting from preform fabrication process. GTS size and purification capacity can be adapted to the number of installed deposition lines and can serve from single MCVD up to 6 (max 10) deposition lines. GTS is designed to operate continuously in automatic mode, with minimal maintenance and expense.
MIF MCVD Furnace System
MIF furnace is used in fabrication of optical fiber preforms by MCVD process using substrate tubes with outer diameter (OD) from 10 to 45 mm. MIF furnace eliminates typical disadvantages of H2/O2 burners
and allows easier, more accurate and repeatable preform collapsing process. It improves final preform geometry, reduces hydroxyl penetration to preform surface, reduces hydroxyl diffusion into core,
and shortens collapsing time by at least a factor of 2. MIF furnace is a valuable tool in core laser fiber preform fabrication and in core preform jacketing.
IDS In-Situ Solution Doping System
IDS solution doping system is used on MCVD preform lathes for in-situ rare earth-doped preform manufacturing. The advantage of IDS over standard solution doping process is in straightforward fabrication process that does not require removal of the substrate tube from the lathe and its integration with OptiFACT control system. This provides a high level of process automation with excellent repeatability. Further benefit is the possibility to repeat the process, depositing and consolidating several layers one after the other and thus producing a preform with larger active core diameter. The IDS system is an add-on for a standard MCVD preform fabrication systems. It can be adapted to any type of preform lathe, but as quoted here, it is intended as add-on to Bimes MDS reform fabrication system using MCVD process and OptiFACT software. IDS functions are integrated into OptiFACT software as an additional device with own control screen.
UVL UV-LED Coating Curing System
UVL UV-LED coating curing system units were developed for curing primary and secondary acrylate coating layers on optical fiber during fiber drawing process, by a major optical fiber manufacturer and were tested in stringent optical fiber production environment, in drawing of different fiber types and
varying process conditions. UVL units replace mercury UV lamps typically used in optical fiber production for many years. UVL advantages over standard UV mercury lamps are in lower power consumption, lower weight, much longer lifetime of LEDs over mercury lamps, lower noise in operation and simpler infrastructure (no need for large cooling air flow). They offer optimized operational cost and lower equipment investment. UVL UV-LED systems are ideally suited for use in research and development facilities, on special fiber draw towers with short distance between coaters and other draw tower components.
TCS Thermal Curing Oven
Optical fibers for high temperature or demanding environment conditions require special coatings. Such coatings are applied by standard coating application equipment but are mostly cured by heath (IR waves). Bimes’ TCS curing systems are used in special fiber draw towers for curing (polymerization) silicones, polyimides, thermoplasts, varnishes or paints and photosensitive coatings.
FPT 4-Point Proof Test System
Conventional techniques for proof-testing apply tensile strain to the fiber which is wound between two capstans. In-between them a load is applied to the fiber using torque control or weighted pulley. This method is used successfully to proof test fiber at strains from 0,2% to about 1% elongation, but at higher
levels than this it is difficult to proof test without damaging the fiber especially when special coatings are used (e.g. polyimide or metal coatings) or when low refractive index special coatings are applied to large diameter laser fibers . At high loads there is considerable pressure between the fiber and the capstan and consequently the fiber surface or coating can be damaged (scratched, deformed, delaminated). To mitigate these shortcomings, the 4-point bending proof test principle was designed.
Carbon and Metal Coating Systems
The advantage of hermetically coated over polymer-coated optical fibers is well-know, as it increases static fatigue resistance of optical fibers and provides a barrier layer against penetration of hydrogen (and other) ions even at elevated temperatures. Hermetically coated fibers are ideal for use in extreme environments with hydrogen atmosphere (low or high pressure) and very high/cryogenic temperatures. Bimes and Plasil MCA metal- and CCA carbon coating application systems are installed in special fiber draw towers for fabrication of different types of optical fibers used in high temperature, geothermal, oil, aerospace, biomedical and defense fields.
FDT Special Purpose Optical Draw Towers
FDT special purpose draw tower are custom developed systems, supplied to known customers, for fabrication of specific optical fiber products. FDT towers are supplied to companies working in industrial sensing, geothermal, oil, biomedical, aerospace, and high-power laser areas. FDT special optical fiber draw tower designs provide the required functionality, combined with high-grade components and instruments and advanced OptiFACT control system, for optimized and repeatable drawing process.
Measuring and Process Control Equipment for Optical Fiber Manufacturing
CCM1000 Fiber Coating Concentricity Monitors
CCM1000 series monitors measure and display fiber coating concentricity errors during the fiber drawing process, using two fast CCD cameras to capture and analyse scattering patterns of the light beams projected on fiber by two laser diodes, positioned at 90° to each other. Fast algorithm permits real time evaluation of coating to fiber non-concentricity, showing also the angle at which the maximum of non-concentricity occurs. With up to 140 frames per second camera speed, CCM can replace traditionally used optical beam and screen concentricity monitor and provide relevant process information at draw line speeds over 2500 m/min.
