Planar and Modular Silicon Package suitable for Future Large-Format 1.9 THz Heterodyne Arrays

Heterodyne detection at sub-millimeter wavelengths is the preferred method for performing high-resolution spectroscopy on interstellar clouds. Realizing large-format heterodyne arrays would significantly improve mapping speed but has shown to be difficult due to the integration complexity of the traditional metal-machined mixer package. This paper discusses the design and performance of a planarly integrated silicon micromachined low-loss waveguide network suitable for use in multi-pixel heterodyne arrays. The network is based on a two-sided RF/LO signal coupling and a quadrature hybrid coupler to combine the two signals before mixing them to an intermediate frequency using two balanced Hot Electron Bolometer mixers. It is shown that the architecture is very suitable for realizing 7 -pixel hexagonal subarrays, and we discuss details of the fabrication, integration, and assembly of a 4-pixel demonstrator array.