Competence Center for Specialty Optical Fibers

Preforms build the base of optical glass fiber manufacturing. In the preform manufacturing our team of experienced technologists uses established processes such as for example MCVD for the deposition of ultrapure fused silica and doping elements from gaseous or vaporable precursors (rare earth elements, aluminum, germanium, phosphorus, boron). Simultaneously, alternative material and preform technologies are beeing developed and implemented to enable completely novel fiber structures and functionalities.

Chemical gasphase deposition (MCVD – solution and gasphase doping) Powder based sintering and crucibel melting technology Polishing of glass tubes inner surface using plasma torch Fully equipped glassblower workshop as well as laboratory for optical quality grade mechanical manipulation of glass (cutting, grinding, polishing) Glassmaker's lathe i.a. for adaption of glass tubes and rods by collapsing, blowing up, stretching, compressing, overcladding, glazing Gas pressure sintering system, isostatic presses and processing furnaces Clean room facility – for staking of glass rods and capillaries made at Leibniz-IPHT to preforms for microstructured and multicore fibers

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Modern special optical fibers have complex, often filigree internal structures or combine extreme material combinations. Years of experience and several individually optimized and adaptable fiber drawing lines qualify the specialists at the CSF at Leibniz IPHT for the manufacturing of even highly complex fibers.

Wide range for setting geometric and kinematic parameters for drawing preforms into fibers, rods and canes Preform rotation Wide temperature range for drawing fused silica and other oxidic, optical glasses Various preform-based drawing processes, e.g. stack-and-draw, rod-in-tube, powder-in-tube drawing processes High-precision pressure and vacuum control of structured preforms during the drawing process for defined manipulation of the target geometry Application-specific fiber coating (up to triple coating) with different high and low refractive index coating materials through photochemical and / or thermal curing

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Whether for special optical fibers or simple telecommunication and data transmission fibers, whether manufactured at Leibniz-IPHT or by cooperation partners - CSF possesses and researches a variety of modification methods of existing optical fibers for subsequent implementation of outstanding photonic properties. If required, we also develop customized optical fiber-based system solutions for research and industry.

Laser-based refractive index structuring for the generation of fiber Bragg gratings (FBG) or waveguide structures

Structuring wavelengths: 248 nm to 800 nm (ns and fs) Structuring of fused silica, non-oxide glasses, crystals and ceramics High grating wavelength flexibility continuously over the wavelength range from VIS to MIR by means of interferometric inscription processes FBG length and position selection over a wide range FBG reflectivity adjustable according to application requirements Spectrally broadband FBGs, e.g. using chirped phase masks FBG inscription during the fiber drawing process (drawing tower gratings)

Fiber Post Processing

Preparation of fiber end faces (polishing of fiber end faces, cleaving of fibers, assembly of special fibers) Manufacturing of fiber tapers: bi-and uni-directional drawing processes using arc or filament-based heat source Design and manufacturing of adapted fiber optic components (splitter, combiner and mode field adapter) Splicing of special fibers (including laser fibers, microstructured fibers, endcaps) Recoating of individual sensor elements up to the entire fiber length Post-processing laboratory (virtual tour)

Fiber optic sensor systems

Advice on and development of tailored fiber optic sensor systems based on fiber Bragg gratings up to industrial production readiness Sapphire fiber Bragg grating based sensor concepts for high temperature diagnostics Customized evaluation routines for: Temperature sensors (3K to 2000 ° C) Strain sensors (0.0001% to 5%) Fast measurement for vibration analysis (> 10kHz)

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Extensive characterization setups and experts with many years of experience allow for the investigation of optical and structural properties of materials, preforms and glass fibers. This ensures close support and optimization of the manufacturing processes. In addition, research groups at Leibniz-IPHT as well as external partners from industry and research, are also beeing supported.

High resoltion determination of refractive index and stress curves in optical preforms and fibers UV-VIS-NIR absorption measurements on compact glass samples Light microscopy with image processing for geometrical analysis (structurs in complex optical fibers as well as bubbles, crystals, phase separation) Spectral characterization of optical glass fibers (attenuation, cut-off wavelength and bending losses) Time and spectrally resolved fluorescence measurements at bulk and on glass fiber samples Tensile strength measurement of fibers Locality determination of defects in optical fibers using OTDR

The following complementary examinations are possible at Leibniz-IPHT as well

microstructure analysis working group of the CMNT of the Leibniz-IPHT

• Structural analysis: scanning electron microscopy (SEM)
• Chemical analysis: Electron probe micro analysis (EPMA) for determination of the concentration of chemical elements
• X-ray diffractometry

working group Optical Fiber Materials and Structures of the Leibniz-IPHT

• Thermochemical properties: differential thermal analysis (DTA) and dilatometer
• Surface characterization of powder samples (BET)

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Modern optical glass fibers are often expected to have specific innovative photonic properties. To achieve this, many optical features and material parameters must be precisely calculated and harmonized with each other. Our simulation experts use optimized scripts and routines based on commercial software such as MATLAB®, COMSOL Multiphysics®, ZEMAX® and Optiwave®, but also in-house developed program libraries.

Simulation of the properties of light Ray optics e.g. light propagation in laser fibers, FBG inscription Wave optics e.g. modal profiles in optical fibers with real-life refractive index profiles, micro structured and hollow core fibers Design of novel optical fibers and of optical structures/optical modules consisting of optical fibers Refined measurement methods and interpretation of complex measurement results and refinement of existing and development of new measurement methods

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