Optically remoted probe for sensing of RF in aerospace radars
The improvement of radar reliability may require the detection and monitoring of its handled power. For this purpose, a new sensor concept based on an optically remoted RF probe was investigated. This work presents such a dedicated photonic system. The optical probe allows dual-regime operations: testing both radar transmit and receive operations. This monitoring performs not only “Go - No Go” tests, but could also be used for calibration. The paper reports the preliminary demonstrations. A new optoelectronic transducer was realised and a mock-up of probe was assembled and tested.
Design, Fabrication and Characterisation of Normal-Incidence 1.56-µm Multiple-Quantum-Well Asymmetric Fabry-Perot Modulators for Passive Picocells
SUMMARY We have designed and fabricated air-bridged modulators with bandwidths exceeding 10 GHz, the highest yet realised to date for InGaAsP/InGaAsP multiple-quantum-well (MQW) asymmetric Fabry-Perot modulators (AFPMs). Microwave modulation, measurements of intermodulation between the photodetected downlink and modulated uplink signals, and bi-directional broadband data over fibre transmission experiments have been performed to verify the potential of the AFPM as a single electrical/optical transceiver. We also report the first direct integration of this AFPM with a microstrip patch antenna and present results of a preliminary microwave signal transmission experiment over a distance of 1.4 m in free-space at 5.2 GHz
Optical emission spectroscopy of self-sustained magnetron sputtering
Abstract The results of plasma investigation during very high power magnetron sputtering processes are presented. Magnetron sputtering during both standard and self-sustained modes was investigated. Owing to very effective target cooling and appropriate magnetic field distribution, the high target power density could be reached (up to ∼1000 W/cm 2 , ∼1.5 A/cm 2 ). A copper target 50 mm in diameter and 7 mm in thickness was used during the experiments. Two modes of magnetron sputtering, i.e. standard and self-sustained, were investigated. Optical emission spectra were measured. The emission intensity of the Cu species as a function of target power density during both magnetron sputtering modes was observed. The spectra were observed in the 200–800 nm wavelength range. When target current rose, the emission intensity of copper ion lines increased and neutrals ones decreased.