S. Detraz

The versatile transceiver proof of concept

SLHC experiment upgrades will make substantial use of optical links to enable high-speed data readout and control. The Versatile Link project will develop and assess optical link architectures and components suitable for deployment at SLHC. The on-detector element will be bidirectional optoelectronic module: the Versatile Transceiver that will be based on a commercially available module type minimally customized to meet the constraints of the SLHC on-detector environment in terms of mass, volume, power consumption, operational temperature and radiation environment. We report on the first proof of concept phase of the development, showing the steps towards customization and first results of the radiation resistance of candidate optoelectronic components.

Modelling radiation-effects and annealing in semiconductor lasers for use in future particle physics experiments

Optical link components used in future particle physics experiments will typically be exposed to intense radiation fields during the lifetime of the experiment and the qualification of these components in terms of radiation tolerance is thus required. We have created a model that describes the degradation of the L-I characteristic of a semiconductor laser undergoing irradiation with the annealing processes taken into account. This model can be used to predict the behaviour of a laser being irradiated with the different particle fluxes at different locations inside a particle physics experiment. The robustness of the model has been checked against the experimental data obtained during high-fluence (in excess of 1015 particles/cm2) neutron and pion irradiation testing in 2009 and 2010.

Neutron and X-ray irradiation of silicon based Mach-Zehnder modulators

We report on our recent investigation into the potential for using silicon-based Mach-Zehnder modulators in the harshest radiation environments of the High-Luminosity LHC. The effect of ionizing and non-ionizing radiation on the performance of the devices have been investigated using the 20 MeV neutron beam line at the Cyclotron Resource Centre in Louvain-La-Neuve and the X-ray irradiation facility in the CERN PH department. The devices were exposed to a total fluence and ionizing dose of 1.2×1015 n cm−2 and 1.3 MGy respectively.

Temperature characterization of versatile transceivers

The Versatile Transceiver is a part of the Versatile Link project, which is developing optical link architectures and components for future HL-LHC experiments. While having considerable size and weight constraints, Versatile Transceivers must work under severe environmental conditions. One such environmental parameter is the temperature: the operating temperature range is specified to be from -30 to +60?C. In this contribution we present the results of the temperature characterization of the VTRx transmitter and receiver. Several transmitter candidates from three different manufacturers have been characterized: multi-mode Vertical Cavity Surface-Emitting Lasers and a single-mode Edge-Emitter Laser. Also both single- and multi-mode receivers have been tested.

Versatile transceiver and transmitter production status

Production of the Versatile transceiver and twin transmitter modules for use in the readout and control systems of upgrading LHC detector systems is starting. We review the performance of the prototypes produced so far and show that the modules are ready for production. We outline the commercial actions being taken to procure parts and assemblies and show the production plan for delivering known good parts in the various flavours required for the upgrade projects that will be using them.

A system-level model for high-speed, radiation-hard optical links in HEP experiments based on silicon Mach-Zehnder modulators

Silicon Mach-Zehnder modulators have been shown to be relatively insensitive to displacement damage beyond a 1-MeV-equivalent neutron fluence of 3⋅1016n/cm2. Recent investigations on optimized device designs have also led to a high resistance against total ionizing dose levels of above 1 MGy. Such devices could potentially replace electrical and/or optical links close to the particle interaction points in future high energy physics experiments. Since they require an external continuous-wave light source, radiation-hard optical links based on silicon Mach-Zehnder modulators need to have a different system design when compared to existing directly modulated laser-based optical links. 10 Gb/s eye diagrams of irradiated Mach-Zehnder modulators were measured. The outcomes demonstrate the suitability for using these components in harsh radiation environments. A proposal for the implementation of silicon Mach-Zehnder modulators in CERNs particle detectors was developed and a model to calculate the system performance is presented. The optical power budget and the electrical power dissipation of the proposed link is compared to that of the upcoming Versatile Link system that will be installed in 2018.

System-level testing of the Versatile Link components

During the first upgrade phase of the Large Hadron Collider experiments, high-speed optical links will be deployed to achieve the bandwidth needed to exploit the increasing luminosity and to allow data acquisition at higher rates. The Versatile Transceiver (VTRx) and Versatile Twin Transmitter (VTTx) modules are in their final development phase before production. They support different link architectures and offer compatibility with either single-mode or multi-mode fibre plants. This paper describes the supported link configurations and presents the system-level testing of the VTRx and VTTx front-end modules with various commercial-off-the-shelf back-end components.

Irradiation of new optoelectronic components for HL-LHC data transmission links

Candidate optoelectronic components for use in future data-transmission links at the High-Luminosity Large Hadron Collider (HL-LHC) were irradiated with 20 MeV neutrons at the University Cyclotron in Louvain-La-Neuve, Belgium and 24 GeV protons at the CERN PS irradiation facility. The results from this test for multi-channel transmitters, Germanium photodiodes, and Silicon photonics modulators are presented here.

Prototype pixel optohybrid for the CMS phase 1 upgraded pixel detector

The CMS Pixel detector phase 1 upgrade calls for an optical readout system operating digitally at or above 320 Mb/s. Since the re-use of the existing link components as installed is excluded, we have designed a new Pixel Optohybrid (POH) for use within this system. We report on the design and choice of components as well as their measured performance. In particular, we have studied the impact upon error-free link operation of the way the data are encoded before being transmitted over the link. We have thus demonstrated the feasibility of operating the new POH within the upgraded readout system.

Passive optical networks for the distribution of timed signals in particle physics experiments

A passive optical network for timing distribution applications based on FPGAs has been successfully demonstrated. Deterministic latency was achieved in the critical downstream direction where triggers are distributed while a burst mode receiver was successfully implemented in the upstream direction. Finally, a simple and efficient protocol was introduced for the communication between the OLT and the ONUs in the network that maximizes bandwidth utilization.