Hybrid polymer/silica vertical coupler switch with <-32 dBpolarisation-independent crosstalk

A modified hybrid polymer/silica 1×2 vertical coupler switch (VCS) with a polymer gap layer and a refractive index contrast of 0.008 has been designed, fabricated and characterised. The VCS exhibits low loss, low crosstalk, low switching power, and polarisation insensitivity. Using the 1×2 VCS as a building block, a 1×8 VCS matrix has been implemented     

QUANTIFICATION OF BITUMEN PARTICLES IN AEROSOL AND SOIL SAMPLES USING HP-GPC

A method for identifying and quantifying bitumen particles, generated from the wear of roadway asphalts, in aerosol and soil samples has been developed. Bitumen is found to be the only contributor to airborne particles containing organic molecules with molecular weights larger than 2000 g pr. mol. These are separated and identified using High Performance Gel Permeation Chromatography (HP-GPC) with fluorescence detection. As an additional detection method Infra Red spectrometry (IR) is employed for selected samples, The methods have been used on aerosol, soil and other samples.     

Sintering Behavior and Optical Properties of Yttria

Sintering in air of a pure yttria powder was investigated on green samples shaped by slip casting. The "relative density/grain size" trajectory has been drawn and hypotheses concerning the mechanisms controlling grain growth and densification were formulated. Samples were fully densified by an additional hot isostatic pressing step on pre-sintered samples. After optimal polishing, optical properties were measured in the UV, visible, and infrared ranges.     

Measurement uncertainties arising from unpowered shipment of dcvoltage references

We have measured the hysteresis in output voltage arising from loss of power for three Fluke 732B dc voltage references. Continuously powering the internal temperature-controlled oven provides the best accuracy with such Zener-diode-based dc voltage references. Batteries are used to provide power continuity when shipping between laboratories. We have shown that for these particular instruments, an apparent hysteresis induced by humidity is likely to dominate any hysteresis arising from loss of battery power when transit between laboratories takes three days or more. Our conclusion is that as much, if not more, care needs to be taken when dealing with humidity than with loss of battery power when shipping between laboratories. When the highest accuracy of dc voltage comparison is required, it becomes necessary to apply voltage corrections using the measured values of humidity coefficients and the relative humidity occurring during transit