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C K Madsen

Publications and source records attributed to C K Madsen.

5 recordsLinked to original sources
PubMed2003

In-line liquid-crystal microcell polarimeter for high-speed polarization analysis.

We report a type of high-speed microcell polarimeter that utilizes microelectrodes, liquid-crystal films, and ultrathin high-contrast polarizers, all integrated between the tips of two optical fibers. When combined with optimized nematic liquid-crystal materials, this compact (2.5 cm x 0.5 cm x 0.5 cm) device offers excellent optical properties and continuous, high-speed operation at > 2 kHz with moderately low operating voltages. It requires no bulk optical elements, and it shows excellent performance when implemented for the measurement of degree of polarization in 10-Gbit/s test systems. Polarimeters based on this design have promising potential applications in polarization analysis for high-speed optical communication systems.

Journal Article↗
PubMed2003

Near-field scanning optical microscopy imaging of multimode interference.

By use of a near-field scanning optical microscope (NSOM) in collection mode, the intensity distribution along a 2 x 2 multimode interference coupler was directly imaged as a function of wavelength. Although calculations can predict the general trend of wavelength dependence and the approximate positions of multiple images in the coupler, the accuracy is poor because of uncertainties in the waveguide width. We show that direct imaging using a NSOM bypasses calculational uncertainties and proves to be a powerful technique for studying these waveguide devices.

Journal Article↗
PubMed2003

Optical filter architecture for approximating any 2 X 2 unitary matrix.

A new optical filter architecture and a new design methodology are presented for approximating any frequency-dependent 2 x 2 unitary matrix that consists of two coupled phase and amplitude responses. Design examples are provided for the compensation of polarization mode dispersion (PMD) by approximating the inverse of a synthesized fiber's Jones matrix. Compensation of the channel PMD over the signal bandwidth is demonstrated, as required for demultiplexing channels in a polarization-multiplexed system.

Journal Article↗
PubMed1974

Increasing rural Head Start children's consumption of middle-class meals.

Rural black, economically impoverished Head Start children, whose normal diets were deficient in nutritional requirements, were not consuming the nutritional breakfasts of, to them, unfamiliar foods provided by the county school system. This study investigated a positive simple method to increase the amount of food consumed and thereby ensure proper nutrition. Teachers dispensed sugar-coated cereal and small candies paired with praise contingent on eating behaviors and rewarded children who finished the entire meal with additional treats and praise. Substantial increases were produced in the proportion of meals consumed and in the number of children observed engaged in eating behaviors. These simple traditional behavioral procedures are readily available for any staff working with economically impoverished children as one method of increasing their sampling and consumption of unfamiliar nutritious foods.

Black or African American↗