1 September 2004 Integrated 1.55 μm photomixer local oscillators for heterodyne receivers at mm wavelengths
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Photomixing is a flexible and efficient method of providing both local oscillator signals for heterodyne receivers and high frequency phase reference signals. Ultrafast, 70 GHz bandwidth, = 1.55 m, photodiodes from u2t Photonics AG have been incorporated into mm-wave waveguide mounts. The photomixers utilise a thin gold probe to couple power into the waveguide and a gold-on-quartz choke filter to deliver photodiode bias. A method of rapidly characterizing the frequency response of these photomixers using spontaneous-spontaneous beating of light from an EDFA is described. Recent work has been directed at increasing the degree of integration of the photodiode, waveguide probe and choke filter to reduce the frequency dependence of the output power. A simplified photomixer block manufacturing process has also been introduced. A combined probe and filter structure, impedance matched to both the coplanar output line on the photodiode chip and to 0.4 height milled waveguide, is presented. This matching is achieved over the W-band with a fixed waveguide backshort. We present modelled and experimental results showing the increased efficiency and smoother tuning. Subsequent integration steps could use the InP photodiode substrate to support the waveguide probe and rf filter. The design and frequency response of such a probe is presented.
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Peter G. Huggard, Peter G. Huggard, Luis Azcona, Luis Azcona, Alexandre Laisne, Alexandre Laisne, Brian N. Ellison, Brian N. Ellison, Pengbo Shen, Pengbo Shen, Nathan J. Gomes, Nathan J. Gomes, Phillip A. Davies, Phillip A. Davies, } "Integrated 1.55 μm photomixer local oscillators for heterodyne receivers at mm wavelengths", Proc. SPIE 5466, Microwave and Terahertz Photonics, (1 September 2004); doi: 10.1117/12.548964; https://doi.org/10.1117/12.548964

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