We demonstrate an ultrafast voltage sampling technique using a stream of electron wavepackets.Electrons are emitted from a single-electron pump and travel through electron waveguides towards a detector potential barrier. Our electrons sample an instantaneous voltage on the gate upon arrival at the detector barrier. Fast sampling is achieved by minimising the duration that the electrons interact with the barrier, which can be made as small as a few picoseconds. The value of the instantaneous voltage can be determined by varying the gate voltage to match the barrier height to the electron energy, which is used as a stable reference. The test waveform can be reconstructed by shifting the electron arrival time against it. We argue that this method has scope to increase the bandwidth of voltage sampling to 100 GHz and beyond.
A new method of driving series arrays of non-hysteretic Josephson junctions using
optoelectronically generated pulses to synthesize a variable output voltage is described.
Electrical pulses from a photodiode are coupled to the array, and the mean output voltage
after filtering is proportional to the pulse repetition frequency with fundamental accuracy.
Numerical simulations of the behaviour of the Josephson junctions have been carried out,
and these results have been verified by experiment. This technique can be easily extended
by using two photodiodes with opposite bias polarities in order to synthesize bipolar
alternating or direct voltages.
The two main modalities for making broadband phase-sensitive measurements at terahertz frequencies are Vector Network Analyzers (VNA) and Time Domain Spectrometers (TDS). These measuring instruments have separate and fundamentally different operating principles and methodologies, and they serve very different application spaces. The different architectures give rise to different measurement challenges and metrological solutions. This article reviews these two measurement techniques and discusses the different issues involved in making measurements using these systems. Calibration, verification and measurement traceability issues are reviewed, along with other major challenges facing these instrument architectures in the years to come. The differences in, and similarities between, the two measurement methods are discussed and analysed. Finally, the operating principles of ElectroOptic Sampling (EOS) are briefly discussed. This technique has some similarities to TDS and shares application space with the VNA.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.