Speaker
Description
Summary
The Versatile Link project aims to provide a multi-gigabit per second optical physical data transmission layer for the readout and control of Super LHC (SLHC) experiments. Point-to-point bidirectional (P2P) as well as point-to-multipoint (PON) architectures are foreseen to be supported by the systems and components currently being assessed and developed. The front-end component that will enable the configuration of any of the Versatile Link’s supported architectures is a bi-directional module composed of both optical transmitter and receiver: the Versatile Transceiver (VTRx).
The components situated on the detectors at the front-end must meet strict requirements imposed by the operational environment for radiation- and magnetic-field tolerance, low temperature operation (between -40 and -10°C), low mass and volume, and low power consumption. The radiation environment is particularly challenging, as any device placed at the front-end must survive the Si-equivalent of 1.5×1015 n (1MeV)/cm2 fluence and 500kGy ionizing dose.
Experience with optical links deployed in LHC experiments has indicated that even the opto-electronic modules situated on the detectors should be sufficiently rugged to allow handling by integration teams relatively unfamiliar with their use. For this reason the VTRx development aims to minimally customize a commercial form factor bidirectional transceiver module that features a direct optical connector interface. The most promising commercial form factor is the SFP+, which measures approx. 50mm long by 10mm wide by 14mm high. Such a commercial module contains a laser diode driver and laser in the transmit path, a photodiode plus transimpedance and limiting amplifiers in the receive path, along with a microcontroller for module control. The VTRx will omit the microcontroller, replace the ASICs with custom-designed radiation resistant versions, and add radiation-resistant commercially available laser- and photo-diodes.
The proof of concept is the first phase of the three-phase Versatile Link project, which for the VTRx means the demonstration that a standard commercial transceiver type can be modified so as: (a) to reduce the material of the commercial package to make it suitable for deployment within SLHC detector volumes; and (b) to include optoelectronic devices of our choosing that we believe will lead to sufficient radiation tolerance and low power consumption. In this paper we will present how be have achieved these goals by providing details of the internals of the module that we have built and showing results of the optoelectronic characterization that has been carried out.
Additionally, a critical requirement for the choice of laser- and photo-diodes to be included in the VTRx is that of radiation resistance. A first survey of devices has been carried out to gauge their resistance to displacement damage (the most challenging type of radiation damage for active opto-electronic devices). This test irradiated a number of commercially-available devices at the neutron irradiation beamline of the Cyclotron facility of the Université Catholique de Louvain. Results will be shown for both irradiation and annealing, leading to preliminary conclusions as the suitability of these commercial devices for use in the VTRx.
