Silicon photonics devices are one of the interesting candidates for future data transmission applications at the HL-LHC. A silicon photonics optical circuit that could modulate, process and detect light signals could be of interest to HEP applications because of its potentially small size, high speed, low power consumption, and integrability with CMOS electronics and design tools. As a first test of their suitability for HEP applications we looked at the effect of ionizing and non-ionizing radiation on Si-based optical modulators provided by the Université Paris Sud.
The effect of radiation on the devices was evaluated in two irradiation tests : an initial test where the devices were exposed to a neutron fluence of 1.2e15 n/cm2 using the 20 MeV neutron beam line at the Cyclotron Resource Centre in Louvain-La-Neuve, and a second test at the CERN PH X-ray facility where they were exposed to a total-ionizing dose of 2 MGy. On-line measurements of the leakage current and modulation efficiency of the devices were performed during the irradiations which allowed us to indicate the level at which the devices start to be affected by radiation. Our results show that while the devices are relatively un-affected by the neutron irradiation we begin to see a degradation in their performance after over a MGy of ionizing radiation.
This paper will present the results from both radiation tests, examine the effect of the radiation on the performance of the silicon-based modulators in more detail, and will conclude by presenting the potential HL-LHC applications for these types of devices.