Electro-optic sampling of planar digital GaAs integrated circuits

Abstract

We report a new electro-optic sampling configuration which allows planar digital GaAs circuits to be probed noninvasively. Our technique employs a novel backside reflecting geometry, in which a laser beam enters the GaAs substrate from the back and reflects from the circuit metallization. By combining the electro-optic effect in GaAs with sub-band-gap (1.06 μm) picosecond pulses from a continuous wave, mode-locked neodymium:yttrium aluminum garnet laser, we are able to make wide-band voltage measurements within GaAs integrated circuits. Results are presented of signals measured on the 2-μm-wide on-chip output line of a medium scale integrated multiplexer/demultiplexer clocked at 2.6 GHz.