Scientific Profile

For several decades, the Leibniz-IPHT has combined research into materials and the development of technologies for the production of innovative optical glass fibers in a unique way in Europe. Great expertise and excellent infrastructural facilities in such diverse areas as material and preform production, fiber drawing, fiber functionalization, fiber and material characterization, as well as modeling and simulation have been concentrated 2021 in the Competence Center for Specialty Optical Fibers (CSF) to push new developments in the field of highly specialized glass fibers at Leibniz-IPHT and to further enhance efficiency.

For the development and manufacturing of innovative fiber concepts, the CSF is scientifically at the forefront and actively supports all research units of the Leibniz-IPHT as well as external partners from research and industry in joint R&D projects.

Preform development

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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Drawing technology for highly specialized fibers, rods and canes

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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Fiber-Post-Processing und functionalization

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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Characterization methods

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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Design and simulation of specialty optical fibers

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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Areas of application

Fibers made in Leibniz-IPHT are used in applications in medical technology, sensors, biophotonics, quantum optics, fiber lasers, information technology / telecommunications

  • Fiber laser and amplifiers (e.g. with Yb-, Er- or Tm-doping)
  • Temperature and strain measurement with fiber Bragg gratings (process and infrastructural monitoring)
  • Imaging (e.g. endoscopy)
  • Spectroscopy (e.g. liquid and gas analysis)
  • Catheters in medical technology

Research Insights

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