The absorption coefficient of p⁺-, p⁻-and n⁻-doped Ga_0.47In_0.53As layers, grown lattice-matched to InP, has been calculated over the wavelength range 1.0–1.7 μm from transmission and reflection measurements.

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. Although we find that the our current system is limited by the experimental line bandwidth to 12–18 GHz, we argue that this method has scope to increase the bandwidth of voltage sampling to 100 GHz and beyond.

The two main modalities for making broadband phase-sensitive measurements at terahertz (THz) 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 analyzed. Finally, the operating principles of electro-optic sampling (EOS) are briefly discussed. This technique has some similarities to TDS and shares application space with the VNA.

A novel measurement system based on an integrated-optic modulator has been used to determine the frequency response of a high-speed GaInAs photodiode. A nominally 8 GHz bandwidth modulator provided a 3μW levelled, continuously tunable, modulated optical signal to greater than 21 GHz. The measured detector 3dB bandwidth was 19.2 ± 0.8 GHz.

A method to traceably calibrate wideband code-division multiple-access (WCDMA) error vector magnitude (EVM) contributions of a source or a receiver is described using a real-time digital oscilloscope as the reference receiver. The results and uncertainties are presented for a receiver calibrated using four WCDMA sources from different manufacturers. The weighted mean EVM of the receiver at 900 MHz is 0.35 $\pm$ 0.03% at 95% confidence. Measurement results at 1780 and 2510 MHz are also reported.

This is the first report of a methodology to provide national standards traceability for EVM measurement of WCDMA RF sources using waveform metrology techniques. The method uses sampling oscilloscopes or real-time digital oscilloscopes. Preliminary results indicate that the rms uncertainty of the modulation waveform, at 95% confidence, is less than 0.3 %.