The HP Agilent 86106B Electrical Plug-In Module has an integrated, calibrated optical channel with a built-in OC-192 / STM-64 filter that can be switched in for a standards-base transmitter compliance test. When the filter is switched out, the 86106B offers 28 GHz of unfiltered optical bandwidth for accurate characterization of high-speed lasers. The frequency-response variation of the unfiltered optical channel also has been improved to minimize the distortion on measured optical pulses. A 40 GHz electrical channel is available for wide-bandwidth measurements on electrical waveforms.