A novel integrated Optical Transmitter for Quantum Communications
We live in the era of digital information, where communications through electronic devices and channels has become an essential aspect in our daily lives, mainly driven by the disruptive and innovative wave of the microelectronics industry, Internet cloud computing, or even streaming services.
Every day, we use computers and smartphones connected to the Internet, unaware, most of the time, on how the information we create, store and share is transmitted through the network. In fact, the transmission of our information may be compromised or even eavesdropped by unauthorized users, who are exploiting the next generation technologies like quantum computers to break the security protocols and gain access to confidential and sensitive data.
In order to guarantee a fundamental trustworthy Internet usage in modern society, we need to implement unbreakable methods beyond classical encryption to prevent and protect data as well as digital privacy not only in crucial sectors such as the governmental, military and finance arenas, but also in other professional and individual areas.
Photonic integration circuits (PICs) are emerging as a potential key technology not only for this digital growth but also to enrich new industrial domains and opportunities.
The notable growth of the photonic ecosystem and maturity during these past decades marks the same trend microelectronics integration did. Just in the same way that billions of transistors, resistors, diodes and capacitors are combined today into compact electronic integrated circuits (EICs), PICs are expected to bring photonic components to the same level while coexisting with electronics.
The current progress in Quantum technologies is expected to promote new opportunities with integrated photonics, opening interesting market prospects in secure communication, aerospace, defence, sensing and LIDAR.
As part of the European Quantum Flagship initiative, the CiViQ project (www.civiquantum.eu) focuses on cost-efficient, high-integration and high-performance quantum communication technologies to deploy Continuous-Variable Quantum Key Distribution (QKD) into the optical telecommunication network infrastructure. In this context, PICs can play a crucial role [Promo video].
To meet this end, CiViQ unites for the first time a broad interdisciplinary community of 21 partners, involving major telecoms, integrators and developers of QKD, experts in their fields. The work targets advancing both the QKD technology itself and the emerging “software network” approach to lay the foundations of future seamless integration of both.
VLC Photonics, a Spanish SME fabless company established in 2011 and partner of CiViQ, offers photonic design-house services that support PIC development, with exceptional know-how in photonic building blocks and system design, circuit layout generation and validation, foundry consultancy and fabrication management, bare-die characterization and testing, and also support on the packaging.
From an industry perspective, reaching scale economies is key to meeting the growing demands for quantum applications. Thus, exploiting semiconductor photonic integration technologies brings strategic opportunities for chip-scale module fabrication as well as supporting design innovation.
VLC is actively involved in CiViQ, facilitating the transformation of a bulky optical system built in a Lab into a photonic integrated design circuit layout, specifically in a standard 4×6 mm² cell-size, sufficiently flexible to satisfy the different requirements from QKD system partners. Taking advantage of the ‘generic purpose’ process available for prototyping and concept validation, the chips can then be fabricated through a JePPIX Multi-Project Wafer (MPW) of the InP foundry of Fraunhofer HHI, another partner of CiViQ.
The first generation of Continuous-Variable QKD transmitter was conceived by QKD system partners Instituto de Ciencias Fotónicas (ICFO, Spain), Centre National de la Recherche Scientifique (CNRS, France), Max Planck Institute for the Science of Light (MPL, Germany), Technical University of Denmark (DTU, Denmark) and Huawei Technologies Düsseldorf (HWDU, Germany) together with HHI and VLC, and consists of a low-linewidth laser and the modulator PIC, which includes a high extinction electro-absorption modulator (EAM), an IQ modulation scheme and a variable optical attenuator (VOA). The compact design exhibits a good compromise between system complexity, redundant optical paths for monitoring the performance and electrical paths distribution for driving the components.
After VLC has provided the specific design of the chip and HHI has fabricated it, the modulation system of the transmitter will be characterized by VLC Photonics as well as ICFO and CNRS, to consider the functionalities as an independent component device. In a second stage, the integrated narrow linewidth laser, currently being developed by HHI, will also be integrated in the transmitter. This integrated transmitter will be then used in Continuous-Variable QKD systems developed within CiViQ to meet network security demands.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 820466