I want to measure Electro-optic reponse of on-wafer optoelectronic device to which RF signal is delivered through probe which is connected to Port1 of VNA. The output optical signal from device goes to the Photodetector which is connected to port 2 of the VNA. Due to mixed connectors i.e. probe on one side and RF connector on the other side I cannot calibrate the system through conventional method as there is no possible way to count in through. I have ISS calibration substrate for on wafer calibration and ECAL module for the off wafer calibration. Can anyone suggest me to perform calibration in this case?