Electrooptic (EO) sampling is a promising technique for the measurement of high speed signals at internal nodes of integrated circuits (ICs). An external transducer1 is needed for electrooptic sampling on Si ICs, and we have fabricated a probe tip using GaAs as the electrooptic material. We demonstrate the application of the GaAs probe tip to high speed sampling using a gain switched l.3-μm wavelength injection laser. The electrooptic modulation is a function of the distance between the probe tip and circuit, and the EO signal measured on test structures at 1.2 GHz is consistent with the prediction of an electrostatic model. At low frequencies (below a few megahertz), the EO modulation in the GaAs probe tip is reduced by an order of magnitude or more. This high pass frequency response is probably due to the conductivity of the semi-insulating GaAs probe tip material.
© 1990 Optical Society of AmericaPDF Article