ISOLATED TEST AND MEASUREMENT PROBE

A test and measurement accessory has an input to receive an input signal from a device under test (DUT), a pilot signal generator to generate a pilot signal, an E/O converter to convert the input signal and the pilot signal to a combined optical signal, an O/E converter to convert the combined optical signal to a combined electrical signal, a signal separator to separate the pilot signal from the combined electrical signal, an amplitude detector to determine amplitude of the separated pilot signal, and circuitry to adjust a gain of a signal path using the amplitude. A test and measurement accessory has an input to receive an input signal from a DUT, an E/O converter to produce an optical signal, an optical splitter to split the optical signal into a feedback portion and a remaining portion, a feedback photodiode to produce a feedback electrical signal to adjust the optical signal.