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ReliabilitY of opto-Transceivers for Health Monitoring Systems

Periodic Reporting for period 1 - RYTHMS (ReliabilitY of opto-Transceivers for Health Monitoring Systems)

Reporting period: 2018-11-01 to 2020-04-30

For aeronautic applications, in-service Structural Health Monitoring (SHM) is now established as a key technique to assess the performance and the integrity of composite aircraft structures for real-time in situ monitoring. In space industry, the Assembly Integration and Test including Electrical Ground Support Equipment is an essential tool enabling a satellite or space launcher developer to integrate and validate the electrical functions of its spacecraft before the launching process. In addition, satellite operators and worldwide SatCom manufacturers are willing to improve the on-board processing capacity, functionality and flexibility.
In this context, RYTHMS will develop optoelectronic transceivers and define tools and methodology to validate and certify such systems in compliance with the general requirements of DO-160 and Space Quality Standards.
Thanks to a complementary consortium involving industrial partners and academics, RYTHMS will design a generic test bench platform for electro-optical characterizations and carry out an optimized program of accelerated tests to predict the reliability.
The RYTHMS project aims to bring the benefits of optoelectronics to aircraft and satellite data communications supporting multiple payload networks and improving performance (connectivity, flexibility, bandwidth, and number of channels). To demonstrate the development of a multi-channel high data rate transceiver (25 Gb/s per channel), a series of activities have been conducted and completed as follows:

Project management conducted and supported by a series of meeting, communication & cooperation between consortium partners (progress reports, planning monitoring…)

Selection and characterization of add-on components required for the opto-transceiver module: define & implement photonic component technology for aircraft environments. Aeronautics environments were defined to achieve performance characteristics of opto-transceiver module regarding environmental requirements focused on aircraft environments sounding with the Topic Manager. The opto-transceiver module specification expressed the main assumption scenario, technologies used, performance, thermo-mechanical stresses, reliability level and environmental requirements included in an aircraft or spatial on-board optical SHM system.

Design/industrialization of a new opto-transceiver module: Adapt existing COTS technology in term of new packaging and high frequency capability for aircraft platforms. Development work during this project’s 1st year revealed some critical difficulties related to the design (supplier maturity, existing toolbox design not compatible with foreseen transmission performances, availability of key components VCSEL at such data rate…) which conduct to re-evaluate the work plan by adding prototyping iteration in order to mitigate the technical challenges. Then a new development approach has been proposed based on 3 prototypes which enable to carry on and secure complementary works until achieving the final demonstrator. The successive demonstrators (version 1 and 1bis) are proposed to use the same active component chipset as the final 4 channel Tx/Rx demonstrator (version 2) and will enable RYTHMS consortium to move forward with the functional evaluations. This activity is in progress.

Design and develop a set of integration test bench: Define a modular infrastructure for transceiver characterization and performance test bench capabilities to demonstrate long term operating mission. They are included in the corresponding technological reports as detailed in deliveries for Electro-optical test bench specifications sent for TM validation on the 08/04/2019. Three partners shared this task depending on test equipment areas on add-on devices and opto-transceiver modules. This activity is in progress.

Develop adequate reliability prediction methodologies: This activity is not yet started even if a preliminary model has been developed in advance and will be presented in a conference at “22ème Congrès de Maîtrise des Risques et Sûreté de Fonctionnement Lambda Mu 22” event to be held in Le Havre (France) in October 12-15, 2020. This paper must be viewed as the next Communication and Dissemination activity.

“Reliability assurance guideline for digital optical transmitter, receiver and transceiver modules”, O. Gilard et al. has been presented at the conference ISROS (International Symposium on the Reliability of Optical Systems) held in November 2019 in Toulouse. It gives an overview of the reliability methodology and platform that is being built in the framework of RYTHMS.
The following focusses on Space application KET (Key Enabling Technology) knowing the Airframe application is the main target of RYTHMS study. But it is of great importance to extend and to show how the break of using such innovative technologies with huge increase of data rate will grow in adjacent market segments allowing their use thanks to the deployment and qualification/certification actions as done by RYTHMS program.
In Europe, THALES ALENIA SPACE and AIRBUS DEFENCE & SPACE have developed and qualified their own Digital Transparent Processor based on the latest state of the art enabling technologies involving deep sub-micron ASIC technology and optical interconnects links at high data rate (> 10 Gbps) for TAS. Nevertheless, the overall capacity of future digital payloads is bounded by overall power and mass/volume budget at satellite level and to remain competitive regarding US manufacturers, we have to improve EU optical interconnect data rate greater than 10 Gbps. SHM concept architecture has to be developed in Europe based on a new generation of optoelectronic transceiver working at high data rate (25Gbps) compatible with the processing specifications. Regarding the market share of the European industry, the major needs will come from the manufacturing Aeronautic market (AIRBUS) foreseen to use hundreds of high data rate optical transceivers modules per airplane to collect and transmit sensor survey data for preventive maintenance of mechanical structures (fuselage, wings, motors…).
Optical transceiver technology becomes a major building block regarding the highlighted aeronautic, space and ground telecommunication needs. There is a large terrestrial market, for which the transceivers are delivered in non-hermetic packages mainly as COTS (Commercial Off The Shelf). For aeronautic and space application, it is considered that non-hermetic packaged devices present higher risk and hermetic packaging is recommended. However, non-hermetic packaging can lead to an order-of-magnitude cost reduction, if the reliability of such devices could be demonstrated.
The establishment of a European supplier for a COTS optical transceiver is considered to be essential in the context of future European space programs, where availability, reliability, cost and schedule are of primary concerns.