We present a process for fabricating ultra-thin silicon chips for submillimeter-wave mixing applications using SOI (Silicon On Insulator) wafers. Such chips allow the profile of the mixer substrate to be minimized within the microstrip channel, thereby simplifying RF design considerations and minimizing machining constraints. The chips feature gold beam leads, RF filter structures, and hot-electron bolometers as the non-linear element. We designed a prototype receiver to demonstrate the feasibility of the ultra-thin silicon chip technology. The receiver has a center frequency of 585GHz and accommodates both diffusion-cooled and phonon-cooled hot- electron bolometer mixers fabricated atop an ultra-thin silicon chip. The chip fits within the microstrip channel of a split-block horn antenna. Protruding from the sides and ends of the silicon chip are thick gold beam leads, which provide electrical and thermal contact between the chip and the waveguide block. In addition, the beam leads provide mechanical support to the chip, allowing the chip to be suspended within the middle of the microstrip channel between the two block halves. Ultra-thin silicon chips with beam leads will facilitate the construction of large format spectroscopic imaging arrays. Such arrays would contain an assembly of individual chips, each featuring a single nonlinear mixing element. The chips could be added, removed of replaced without disturbing the rest of the elements within the array. There are myriad potentials for such systems; examples include atmospheric research, astrophysics, and security systems.

In many low-mass X-ray binaries the optical light is dominated by an accretion disk. The bulk of the accretion disk is ionized, and in many models the surface layers are threaded by a magnetic field. Polarimetric observations can give information on the scattering properties of the disk surface. Polarimetric observations of three low-mass X-ray binaries, Sco X-1, Her X-1 and XTEJ 1118+480, in optical wavelenghts are presented. A strong interstellar polarization component dominates the polarization of Sco X-1, but we also detected its weak intrinsic linear polarization. Marginally variable polarization is possibly seen in XTE J 1118+480. The circular polarization of Sco X-1 and XTE J1118+480 is consistent with zero. Contrary to previous claims, the linear polarization of Her X-1 seems to be constant. The observed polarization can be explained with a combination of interstellar polarization and electron scattering in the ionized accretion disk. We also derive the upper limit for the large-scale ordered magnetic field in the accretion disk. Some linear and circular polarimetry for the high-mass X-ray binary SS 433 is also presented.

EcologyVolume 71, Issue 5 p. 2030-2030 Article How-to Book for Phenolics Lovers Karl W. Kleiner, Karl W. KleinerSearch for more papers by this authorJack C. Schultz, Jack C. SchultzSearch for more papers by this author Karl W. Kleiner, Karl W. KleinerSearch for more papers by this authorJack C. Schultz, Jack C. SchultzSearch for more papers by this author First published: 01 October 1990 https://doi.org/10.2307/1937615AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume71, Issue5October 1990Pages 2030-2030 RelatedInformation