News briefs

1994 Journal of Research of the National Institute of Standards and Technology  
NIST TRANSFERS FABRICATION TECHNOLOGY FOR JOSEPHSON-JUNCTION VOLTAGE ARRAY STANDARDS TO A PRIVATE U.S. COMPANY NIST has successfully transferred the technology for fabricating Josephson-junction voltage standard array chips to a private U.S. company. NIST had been seeking to develop a U.S. commercial supplier for chips to relieve its position as the only source in the world of metrologic-quality devices. Following NIST assistance, the company was able to fabricate a quantity of operating 1 V
more » ... ps in a design having 3600 junctions about a year ago. NIST tested these devices to confirm their operation and subsequently certified them for delivery to other organizations; ten have been shipped for use in calibrations. The reliability of the private company devices has been demonstrated to date in that there have been no failures during the time approaching 1 year that the devices have been in commercial service. More recently, the company has been successful in fabricating 10 V chips, in a design having 20208 junctions, that also have been certified by NIST. The division expects that future orders to NIST for 10 V Josephson standards will be satisfied with the private company or other commercial devices. Josephson voltage standard systems play a critical role for a number of U.S. companies. The Josephson measurement systems of three companies provide the only means they have to confirm the performance of their high-accuracy voltage measurement and reference instrumcnls. Two aerospace companies use Josephson systems to meet the calibration requirements for large DOD procurements. Systems at six U.S. national anil military standards labs provide the foundation of voltage metrology for the country. NIST DEMONSTRATES INTEGRATED OPTICAL POLARIZATION DIVERSHT RECEIVER NIST scientists have successfully demonstrated a fully integrated optical polarization diversity receiver. The receiver exhibits the advantages typical of integrated optical devices: it is small (2 mm X 20 mm), rugged, and easy to fabricate. Polarization diversity receivers provide a means for separating components of an incoming signal of mixed polarizations and, as such, find uses in sensing and communications applications, including polarimetric optical sensors, machine tool positioning sensors, magnetic read head positioning .systems, optical read heads for compact disk drives, and coherent communication systems. A CRADA partner is interested in using the receiver in vehicle sensor applications. The device consists of a Y-branch waveguide splitter, with a one-degree splitting angle, formed by potassiumsodium ion exchange in silicate glass, A liydrogenated-amorphous-silicon cladding is deposited on each branch of the splitter to act as a polaii/er. One output cladding is individually trimmed lo a thickness which attenuates the component of guided light having a transverse electric field, while the other cladding is trimmed to attenuate light having a transverse magnetic field. The device is trimmed by a NIST-patcnted process of localized plasma etching which allows in situ extinction optimization by monitoring transmitted liplit. Extinction ratios of 27 dI3 have been demonstraicd for the polarizers using cladilings 1.2 mm in kiigth. The device is completed with the deposition <i(
doi:10.6028/jres.099.063 fatcat:crbdeapp5jb2dihldl66mkcgpm