The XPDV412xR family contains two photodetector devices, with optimized ultrafast photodiodes with up to 100 GHz bandwidth. Both photodetectors, the XPDV4120 (f3dB > 90 GHz) and XPDV4121R (f3dB >100 GHz), are designed with waveguide-integrated photodiodes and show an extremely flat frequency response in power and in phase. The on-chip integrated bias network with optimized RF design in particular, ensures undisturbed frequency response from DC to the 3 dB cut-off frequency and saves costs for internal bias-tees. The devices are especially developed for optimal RF performance revealing virtually no pulse response ringing.
Both photodetectors are characterized in the frequency domain by using a heterodyne technique. In the time domain, a femtosecond pulse source and a 65 GHz sampling oscilloscope are used to measure the pulse response.