Schlüsselwörter
(Englisch)
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Photonics components, photonics systems, non-standard optical fibres, new multimode fibres, measuring instruments for photonics, process and quality control, THz metrology, optical metrology, optical printed circuit boards.
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Kurzbeschreibung
(Englisch)
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The huge potential of photonics and fibre optics is evident from the Photonics21 Strategic Roadmap listing the major photonic research and innovation challenges. One challenge has been that modern photonic systems utilise novel components, whose dimensional and optical properties cannot be reliably measured using current techniques: commercial instruments are often uncalibrated, provide insufficient accuracy and are available only for some of the required characteristics. Thus, new traceable and improved measurements and calibration methods are needed to make photonic measurement technology an enabling technology that will allow technological breakthroughs as well as commercialisation of sophisticated fibre optic components.
- Improving online measurements of dimensional parameters (diameters and concentricity) during fabrication will benefit manufacturing of special fibres and capillaries.
- Evaluation of the performance of photonic components in optical interconnects and the next-generation of microwave or THz transmission links, traceable measurements of key parameters (dynamic range, insertion loss, bandwidth, etc.) as well as industry standards is necessary.
- The development of traceable measurement techniques to study environmental effects on the boards such as temperature cycling, ageing, humidity variation, etc. will help the data communications industry to understand the performance of optical printed circuit boards within their working environments.
- Coupling light without losses from fibres into optical circuits presents a challenge due to the large mode mismatch. Efficient solutions for matching conventional fibre-coupled systems to nanophotonic devices are needed.
- The metrology for measuring modal distribution in multimode plastic optical fibres used in high bitrate multi-purpose optical networks is still not sufficient, leading to inconsistent measurement results that have a negative impact on the deployment of these systems.
- Novel optical fibre measuring instruments, like the high-resolution optical time-domain reflectometer, offer performances which cannot be adequately evaluated because of the lack of suitable calibration artefacts and procedures.
Optical communications, biophotonics, avionics, and automotive industries are examples of fields that will benefit from the improved measuring capabilities.
This is a joint research project carried out in the framework of the European Metrology Programme for Innovation and Research (EMPIR) (see:http://www.euramet.org/research-innovation/empir/). The EMPIR initiative is co-funded by the European Unions's Horizon 2020 research and innovation programme and the participating states. METAS is one of the project partners in the project.
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Projektziele
(Englisch)
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The objectives of the project are:
- To develop traceable online and offline metrology techniques for characterisation of advanced optical fibres and photonic components – by developing measurement setups, procedures and numerical tools. Especially, the project will develop methods for thickness and concentricity measurements of different fibre layers with target accuracies of 0.5 μm and 1 μm, respectively, and for dispersion and optical parameter measurements in high power applications. The goal is to measure the relative content of light in the core with an accuracy of ±5 %.
- To develop metrology for improved traceability of fibre optic measuring instruments – by developing calibration techniques and artefacts. The main goal is to develop a traceable measuring system for encircled angular flux, which is a key parameter allowing characterisation of modal distribution in multimode fibres and components. Artefacts will be developed for the calibration of the attenuation scale and the distance scale of multimode optical time domain reflectometers (OTDR). Additionally, a novel portable absolute standard detector based on carbon nanotubes at cryogenic temperatures will be developed to solve the issues inherent to existing transfer standard detectors, like spectral dependence and temporal drift, and shorten the traceability chain of optical power measurements. This will result in a lower measurement uncertainty (target accuracy better than 0.5 %).
- To develop metrology for terahertz transmission links – by developing traceable measurement standards and measurement procedures for key parameters (dynamic range, insertion loss, SNR, bit error ratio (BER) for various modulation formats, free spectral range and bandwidth) of THz transmission links. The target accuracy for dynamic range and insertion loss measurements is 5 %.
- To establish the metrology tools for performance characterisation of polymer waveguides mounted on electronic circuit backplanes used in high-speed data links – by developing measurement systems that can characterise the functional performance of waveguides incorporated onto short range interconnect boards. The systems will assess the key parameters of attenuation, isolation and BER. The usability of typical fibre-to-fibre connectors at high average powers will be investigated by monitoring transmission as well as the heating of the components (target accuracy: ±5 %). Measurement strategies to characterise evaluation boards will be developed with accuracy levels within ~ 1 dB for attenuation.
- To engage with the European photonics industry and photonics equipment manufacturers – to facilitate the take up of the technology and measurement techniques developed by the project, and to recommend what further actions are required to ensure uptake.
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Abstract
(Englisch)
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The main objective of this project was to develop new measurement systems, as well as traceable artifacts for the metrology of optical fiber systems and components, in order to optimally respond to new needs in this field. To do this, the following developments have been completed:
- -A reference system for the measurement of encircling angular flux (EAF) has been successfully developed in conjunction with an English industrial partner. This quantity makes it possible to quantify the modal distribution in multimode step-index optical fibers. Exact measurement of this magnitude plays a fundamental role, particularly in ensuring accurate and repeatable loss and bandwidth measurements in systems using such fibers. The traceability of the system built at METAS has been established by developing a whole series of specific calibration methods, and validation has been successfully achieved by inter-comparison with a second equivalent system, manufactured by the industrial partner.
- A set of tools allowing simulation of modal distribution in any type of fiber has been developed jointly by METAS and a German industrial partner specialized in finite element simulation. The algorithms developed allow, among other things, an estimation of the coupling losses between fibers, and open the door to the definition of limit values for the modal distribution. A validation of the implemented algorithms has been successfully performed, compared with purely analytical evaluations.
- A series of artifacts allowing the calibration of the distance scale of very high resolution optical reflectometers has been developed at METAS and successfully validated by inter-comparison with reference instruments. In particular, they allow the calibration of photon counting OTDR reflectometers as well as reflectometers with low coherence length (OLCR).
- A spectral reference attenuation artifact with modal distribution control has been developed further. Such a reference is ideally suited to calibrate the attenuation scale of multimode OTDR reflectometers. A particular calibration method was developed to establish the traceability of this reference, and its validation was carried out through a series of inter-comparisons, conducted jointly with a Canadian instrument manufacturer. The very good results obtained have shown the interest of these references for the calibration of this type of instruments.
- METAS also contributed to the implementation of a fiber-optic cryogenic radiometer, in a joint activity with the CMI. A fiber optic switch has been developed, built and fully validated at METAS. It allows a direct calibration of an instrument compared to the radiometer, without the need to swap the instrument to be calibrated and the cryogenic radiometer.
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Umsetzung und Anwendungen
(Englisch)
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The EAF measuring instrument, as well as the artifacts developed within the framework of this project, open the door for METAS to perform calibration services in new areas, such as those related to multi-mode step-index optical fibers, and wide cores, as used in the automotive field, or for high resolution reflectometry. The development impact on IEC standardization work is certain, and contacts have already been established with the ad hoc working groups.
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Publikationen / Ergebnisse
(Englisch)
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Castagna, N., Morel, J., Robinson, E., Yang, H., "Traceable instruments for Encircled Angular Flux measurements", Proc. SPIE 10683, 106831B (2018). Oral presentation.
Castagna, N., Morel, J., Testa, L., Burger, S., "Modelling of standard and specialty fibre-based systems using finite element methods", Proc. SPIE 10683, 1068336 (2018). Poster presentation.
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