A probe for testing very high frequency circuit chips (34) includes a flexible membrane (12) having test probe contacts (14), arranged to contact pads (32) on the device under test to bias up, drive and load down the circuit under test. Various optically-addressable devices (68,130,202) are mounted on the membrane and either excited or probed by a laser beam (66) to transmit and/or sense very high frequency electrical signals to/from the device under test. The optically-addressable devices are excited or probed by a high bandwidth laser (64,66), and thus very high speed circuits may be driven by contact pads on the probe membrane and probed by a laser beam. Employing an optically transparent membrane (200) having test probe contacts (206,208) for bias, driving and loading a circuit under test, and having an electro-optic polymer layer (102, 202), a probing laser beam (204) may be directed through the membrane and the electro-optic polymer layer to sample an RF field generated by a device (214) under test. Measurement of internal circuit node voltage wave forms in the electro-optic substrate of a device (34, 50) under test may be accomplished by using test probe contacts (14, 55) to bias, drive and load the device under test while transmitting a laser probe beam (46, 76) through the membrane and electro-optic substrate.