Widely tunable electrooptic pulse-pattern generation and its application to on-wafer large-signal characterization of ultra high-speed electronic devices

A pulse-rate-tunable, electrooptic pulse-pattern generator and a wideband high-efficiency optical-to-electrical (OE) conversion stimulus probe have been developed. Sinusoidal electrooptic amplitude/phase modulation and chirp compensation were used to provide picosecond pulsation, and the relationship between pulse-rate tunability and the extinction ratio has been studied analytically and experimentally. Return-to-zero (RZ) pulse patterns of 10-72 Gb s^-1 have been generated by using LiNbO₃ amplitude/phase modulators with a bandwidth of 18 GHz, a single dispersion shifted fibre, and a time-division multiplexer. A 1.55 μm waveguide p-i-n photodiode yielded high responsivity (0.75 AW^-1) and a saturation peak voltage of 200 mV at the probe tip. The measured effective 3 dB bandwidth exceeds 50 GHz, which is currently limited by the frequency dispersion of the coplaner waveguide (CPW) used in the probe. Use of this generator and probe, in combination with electrooptic sampling, for on-wafer characterization of a broadband distributed amplifier revealed the amplifier's saturation characteristics and waveform distortion under actual operating conditions with a 64 Gb s^-1, 120 mV per probe, RZ pulse-pattern input.