Metrology for the photonics industry - optical fibres, waveguides and applications

By 2025 the global market for photonic products is expected to be around €854 BN and in 2017 Europe’s global market share was 15.5%, making it the second-biggest supplier of photonics worldwide.

However, many modern photonic systems use components with novel dimensional and optical properties which manufacturers could not reliably measure using current techniques. New metrology was therefore required to promote this technology further and maintain European competitiveness in this field.

Data centres are constrained by data transmission capacity to outside networks. Replacing metal wire-based interconnects with optical printed circuit boards (OPCBs) would reduce energy consumption whilst increasing bandwidths but the effect of the operational environment on OPCBs was not fully understood. THz interconnects, utilising the electromagnetic spectrum between radio waves and infrared light, could enable faster data connections, but many parameters required for their characterisation could not be adequately measured with existing methodology. The path that light travels through an optical cable, its ‘modal’ distribution, can minimise signal loss, increase bandwidth and help locate faults. Encircled Flux (EF) is a measurement parameter for determining modal distribution but is not suitable for all fibre types and improved methods such as Encircled Angular Flux (EAF) lacked SI traceability.

This project delivered new methodology and instrumentation to address the innovation challenges facing the photonics industry

• A novel primary standard radiometer was developed for absolute optical radiation power measurements. Based on carbon nanotubes held at cryogenic temperatures it has both an improved uncertainty and one-step traceability to the SI.
• An interferometer for broadband spectroscopy at THz frequencies was designed and built and a thorough characterization of THz emitters performed.
• Innovative devices were developed for silicon photonics, with compact footprint and enhanced performance.
• New calibration techniques and performance enhancement strategies for fibre sensors were developed, providing improved uncertainty, enhanced resolution and sensitivity.
• Metrology that was not available at the start of the project was developed for OPCBs, including a characterised measurement system incorporating methods to monitor board performance under a range of controlled environmental conditions.
• A fully traceable EAF measuring system for the calibration of multimode systems was developed and six new calibration services were established.

Project results were incorporated into a best practice guide detailing procedures for high power fibre optics and into the analysis software JCMsuite including computational methods to determine the optical properties of nano and micro devices. The techniques for characterising EAF measurement instruments have already seen commercial uptake into advanced instrumentation. The work performed will support the manufacturing of completely new products, improve the competitiveness of the photonics industry and help maintain Europe’s position on the global stage.

EMPIR project 19SIP05 TTPWC builds on this work.