The DUX-25 after Twenty-Five Years: New Analyses and Reference Data.

Twenty-five years after its inception, we present new analyses and reference data for the DUX-25, a questionnaire on health-related quality of life for children 8-17 years old and their parents as proxy. Data from 774 healthy children and their caregivers were collected through web-based data collection. Participants were recruited via primary and secondary schools in the Netherlands. The DUX-25 showed adequate psychometric qualities. Using exploratory and confirmatory factor analyses, we were able to support the theorized four-factor model. In addition, a model with five factors emerged in which the factor 'Social' was divided into 'Social Close' and 'Social Far'. A comparison of the outcomes of the PedsQL with those of the DUX-25 provides evidence for a high construct validity of the DUX-25. With the new updated reference data, the DUX-25 can still be used in inpatient and outpatient settings to measure health-related quality of life of children with chronic conditions.

Ultrashort pulse propagation in multiple-grating fiber structures.

We propose a multiple-grating fiber structure that decomposes an ultrashort broadband optical pulse simultaneously in both wavelength and time. As an initial demonstration, we used a transform-limited 1-ps Gaussian pulse centered at 1.55 mu;m as the ultrashort broadband input into a three-grating fiber structure and generated three output pulses separated in wavelength and time with good correlation between experimental results and simulations. This device structure can be used to generate a multiwavelength train of pulses for use in wavelength-division-multiplexed systems or to implement frequency-domain encoding of coherent pulses for optical code-division multiple access.

Picosecond carrier lifetime and large optical nonlinearities in InGaAsP grown by He-plasma-assisted molecular beam epitaxy.

We report the measurement of a fast carrier lifetime and large band-gap-resonant optical nonlinearities in an InGaAsP sample grown by He-plasma-assisted molecular beam epitaxy. Using a 2-microm-thick sample grown on an InP substrate, we observed a carrier lifetime of 15 ps and an index change as large as 0.077 induced by an intense 1-ps pulse at a wavelength of 1.57 microm. Good crystalline structure is maintained in the material during growth, and the absorption spectrum shows a sharp band edge. These properties indicate that materials produced by He-plasma-assisted growth have potential applications in compact ultrafast photonic devices.