Practical comparison of optoelectronic sampling systems and devices

Three different sampling systems using optoelectronic switching have been constructed and compared. The first system used two wavelengths of light: one to switch between conductors and the other to switch to ground. Sampling measurements were made on an X-band trapatt diode. The second system used a single wavelength (0.53¿m) to effect the switching between conducting lines or to ground. This newer system used coplanar guides with earth shields, and used significantly less optical pulse energy to effect the switching. A 10 ps sampling system was constructed and tested on a novel 10 ps impulse generator. Constant energy in each laser pulse could permit considerable reduction in the required optical pulse energy. The paper is terminated with a demonstration using about 1 pJ of energy from an injection laser to form a 300 ps optoelectronic sampling system. Although this is slower than conventional sampling systems it is capable of handling signals from 20 mV to over 100 V, demonstrating the robustness of optoelectronic switches. Improvements are expected in the future.