RF Waveform Noise Measurement by Electro-optic Sampling

The quickly increasing bandwidths of high-speed RF electronics, reaching already hundreds of GHz, create a need to characterize the wideband RF waveforms, as well as assess their noise. In particular, one of the challenges is to synchronize the wideband RF waveforms to optical clock signals by minimizing the time-interval-error jitter between the two signals. This way the RF waveforms may be used to modulate optical pulses for high-speed classical or quantum optical telecommunication. Here we show the experimental demonstration of electro-optic-sampling-inspired measurement of the repetitive RF waveform and its noise. We used commercially available traveling-wave electro-optic phase modulator in the Mach-Zehnder interferometer and a pulsed probing laser to measure the applied phase waveform on the pulse-by-pulse basis. provides the RF signal's amplitude noise and timing jitter by exploiting their different natures. We employed our method to high-frequency single-tone signals, as well as, to photonically generated high-speed pulses from a photodiode, measuring timing jitters of 240 fs and sub-8 fs, respectively. Our technique does not require any wideband RF measurement devices such as oscilloscopes or VNAs and can be employed in most telecom laboratories.