Abstract
Planar ortho-mode transducers (OMTs) are a commonly used method of coupling optical signals between waveguides and on-chip circuitry and detectors. While the ideal OMT–waveguide coupling requires minimal disturbance to the waveguide, when used for mm-wave applications the waveguide is typically constructed from two sections to allow the OMT probes to be inserted into the waveguide. This break in the waveguide is a source of signal leakage and can lead to loss of performance and increased experimental systematic errors. Here, we report on the development of new OMT-to-waveguide coupling structures with the goal of reducing leakage at the detector wafer interface. The pixel-to-pixel optical leakage due to the gap between the coupling waveguide and the backshort is reduced by means of a protrusion that passes through the OMT membrane and electrically connects the two waveguide sections on either side of the wafer. High-frequency electromagnetic simulations indicate that these protrusions are an effective method to reduce optical leakage in the gap by \(\sim 80\%\) percent, with a \(\sim 60\%\) filling factor, relative to an standard OMT coupling architecture. Prototype devices have been designed to characterize the performance of the new design using a relative measurement with varying filling factors. We outline the simulation setup and results and present a chip layout and sample box that will be used to perform the initial measurements.
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Acknowledgements
Work at Argonne, including use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences and Office of High Energy Physics, under Contract No. DE-AC02-06CH11357. Ansys: https://www.ansys.com/products/electronics/ansys-hfss
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Gualtieri, R., Barry, P.S., Cecil, T. et al. Optical Leakage Mitigation in Ortho-Mode Transducer Detectors for Microwave Applications. J Low Temp Phys 209, 314–321 (2022). https://doi.org/10.1007/s10909-022-02733-9
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DOI: https://doi.org/10.1007/s10909-022-02733-9