Wireless interrogation of an optically modulated resonant tunnelling diode oscillator

n this work, a resonant tunnelling diode-photo-detector based microwave oscillator is amplitude modulated using an optical signal. The modulated free running oscillator is coupled to an antenna and phase locked by a wireless carrier that allows remote extraction of the information contained in the modulation. An off-the-shelf demodulator has been used to recover the envelope of the baseband data originally contained in the optical signal. Data were successfully transmitted at a rate of 1 MSym/s with a bit error rate below 10−6

Identification of V-band frequency-selective surface at 11 m standoff distance with a transceiver chipset

The authors demonstrate the detection of a millimetre wave frequency-selective surface with a null near 60 GHz at large standoff distances (≥10m) such as would be required for covert security labelling and anti-counterfeiting applications. The authors compare the performance of using lenses and offset parabolic reflector to improve the directivity of a commercial, compact, integrated chipset in a ball grid array package, finding a reduction in beam width from 60 to 5 and 10°, respectively. They measured the power spectrum of the system with no label at distances of 35 cm, 60 cm, 4 m and 11 m finding no appreciable fading effect with the higher-directivity system. The integrated system-measured response of the frequency-selective surface agreed well with that of a standard test set-up (horn antennas and vector network analyser) as well as numerical simulations conducted with a frequency-domain solver (HFSS)

V band scanner system based on ball grid array-integrated circuit transceiver chip set automation

The authors present and experimentally evaluate a scheme for measuring the frequency response of propagation channels and frequency-selective surfaces (FSSs) from 56.5-62-GHz in the US-defined license-free industrial, scientific and medical band using a commercially available millimeter-wave transceiver chip set. The authors exploit the chipset-s IQ modulation scheme to produce a single sideband signal that allows the magnitude of the baseband signal to be correlated to the carrier power. Data can be recorded at 600 different frequencies in the band in 130-s, while the fastest scan the authors demonstrate gives 12 frequency points in 2.6-s. The authors expect that further savings can be made by miniaturising the system and eliminating latency associated with the use of general-purpose test equipment. Hence, it is expected that a fast, portable device for the identification of hidden millimetre-wave security labels, based on FSSs, can be constructed from this architecture

An optical to wireless data link using radio frequency backscatter

The changes in the impedance of an antenna-coupled photo-detector under optical illumination are used to encode data on a backscattered wireless signal similarly to the standard techniques used for radio frequency identification and tagging. The effect is strong enough to allow retrieval of the information without requiring a dc supply at the optical to wireless interface

Delayed feedback dynamics of liénard-yype resonant tunneling-photo-detector optoelectronic oscillators

We use the nonlinear dynamics approach for studying delayed feedback optoelectronic oscillators (OEOs) formed by hybrid integration of resonant tunneling diode (RTD) photo-detectors with laser diodes, in both single and dual optical fiber feedback routes. In the single loop topology, the performance of the RTD-OEO free-running self-sustained oscillator is improved in terms of phase noise, with a compromise between the delay line and the strength of the optical re-injection. In the dual-loop configuration, superior performance is achieved due to the suppression of the side modes associated with the optical cavity length, resulting in a side mode suppression ratio of up to -60 dBc of the carrier frequency. We compare experimental results with numerical simulations based on a system of delay differential equations comprising a Liénard oscillator model driven by white Gaussian noise and coupled with laser rate equations. The delayed feedback Liénard oscillator model gives considerable insight into the RTD-OEO dynamical regimes predicting its main features in both single- and dual-loop configurations