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The idea of implanting microphotodiode arrays as visual prostheses has aroused controversy on its feasibility from the moment it appeared in print. We now present results which basically support the concept of replacing damaged photoreceptors with subretinally implanted stimulation devices. Network activity in degenerated rat retinae could be modulated(More)
A study of frequency stability and power scaling of single-mode GaSb-based 2.05-μm semiconductor disk laser (SDL) modules is presented. Single-mode emission and wavelength tuning over a range of 120 nm is accomplished by inserting a birefringent filter into the cavity. In order to evaluate the frequency stability, heterodyne beat-note linewidth(More)
This paper gives an overview on the design, fabrication, and characterization of quantum cascade detectors. They are tailorable infrared photodetectors based on intersubband transitions in semiconductor quantum wells that do not require an external bias voltage due to their asymmetric conduction band profile. They thus profit from favorable noise behavior,(More)
The determination and unambiguous identification of carotenoid stereoisomers from biological tissues, avoiding isomerization and oxidation due to the extraction process, is still a major challenge. Particularly, the analysis of lutein and zeaxanthin stereoisomers is of great importance, as these are the main constituents of the macula lutea, the central(More)
We report on the realization of an optically pumped semiconductor disk laser (SDL) emitting at 2.25-mu m wavelength with a cavity containing two separately pumped (AlGaIn)(AsSb) gain chips. Compared to single-chip SDLs, the dual-chip configuration allows launching a significantly larger amount of total pump power into the laser chips prior to reaching(More)
High performance single pole double throw (SPDT) and single pole triple throw (SPTT) switches optimized for center frequencies of 94 GHz and 77 GHz, were realized in coplanar waveguide GaAs MMIC technology using resonated PIN diodes. SPDT switches are shown with 1.3 dB (<1.6 dB) insertion loss and 22 dB (>21 dB) isolation at 94 GHz (entire W-Band). SPTT(More)
An efficient reversed-phase high-performance liquid chromatographic assay with ultraviolet detection at 450 nm for simultaneous determination of lutein and zeaxanthin stereoisomers in bovine retina is described. The procedure involves rapid and careful one-step hexane extraction of the carotenoids from the homogenized liquid and enrichment by on-line solid(More)
CSP postulates perceptual grouping of an acoustic continuum into sharply delimited phonological categories with discrimination maxima across the identification boundaries. The experimental procedure was applied to F0 contours in a peak-shift and semantic contextualization paradigm in German and showed a categorical change from early to medial position in(More)
We report on the operation and beam profile analysis of an optically pumped GaSb-based vertical-external-cavity surface-emitting laser at 2.33 /spl mu/m. To compensate for the low thermal conductivity of the laser chip, an intracavity heat spreader made from polycrystalline chemical vapor deposition diamond was bonded to the top surface of the chip. In this(More)