Bit Error Rate Measurements on Prototype Digital Optical Links for the CMS Tracker

Two prototypes of a four-channel digital optical link to be used for the slow control of the CMS Tracker detector were tested for bit error rate, at transmission rates of 40 Mbit/s and 80 Mbit/s. Both prototypes used the same transmitter and PIN photodiode, but different receiver configurations: one used COTS electronics, whilst the other used a digital receiver ASIC developed at CERN in a 0.25 mm process. Both links proved to be well within the specification limits even after the ASIC receiver was irradiated to a 20 Mrad total dose, and the PIN photodiode to a 6.5á1014 n/cm2 fluence.