The MN4765B module calibrates optoelectronic (O/E) measurements using VectorStar VNAs. It contains an InGaAs photodiode that converts optical signals to electrical for calibration from 70 kHz to 70 GHz and 1550 nm. The module is characterized for magnitude and phase using a NIST standard and provides stable, accurate O/E measurements up to +6 dBm input power.