Our own Optagon Photonics (http://www.optagon-photonics.eu/), led an innovation project aiming at the fabricationof a photonic integrated circuit (PIC) and its demonstration as a compact optical equalizer for optical interconnects.

The design of the PIC was based on an IP protected concept of Optagon Photonics. It involved the use of 9 micro-ring resonators as tunable delay lines inside a 3-tap filter architecture. The low-level mask design was made by Bright Photonics and the fabrication was realizedby LioniX International on its commercial silicon nitride platform known as TriPleX. Finally, the testing of the PIC was carried out in the system lab of the National Technical University of Athens using the smart electronic control unit of Optagon Photonics.

The results validated the potential of the optical equalizer fordrastic signal quality improvement and bit error correction in the case of signals with severe bandwidth limitations. They also confirmed its possibility for adaptive operation at variable symbol rates and for parallel processing of multiple WDM channels.These results have been published in the December issue of the IEEE Photonics Technology Letters (https://ieeexplore.ieee.org/document/9247259).

Moreover, an extensive description of the optical equalizer and its perspectives for the future of optical communications was presented by LioniX International (https://www.lionix-international.com/low-error-data-transmission-with-an-integrated-photonic-optical-equalizer/) as part of its campaignfor its presence in the exhibition of the European Conference on Optical Communications(ECOC 2020).

As next steps, Optagon Photonics is now aiming at the redesign of the optical equalizer to accommodate operation at 100 Gbaud and beyond, and at the investigation of its use in quantum optical links for quantum key distribution (QKD) with increased key rates.