Application of smoothing techniques to relief-type resist surfaces generated by direct write electron-beam lithography

Complex relief-type resist surfaces are of increasing interest for applications in optical and photonic devices. They can be fabricated by using direct write electron beam lithography. The crucial point in the fabrication of such reliefs is the inexact approach to the desired resist profile and the increased roughness of the resist surface. This work focuses on three important steps towards a better realization of smooth profiles, i.e. an improvement in beam position accuracy, a reduction of exposure errors caused by the insufficiency of the conversion software and a smoothing technique applied after development. The introduced techniques are expected to considerably improve the functionality of relief type devices

The neural circuitry involved in the reading of German words and pseudowords: A PET study

Contains fulltext : 14184-OA.pdf (publisher's version ) (Open Access)Silent reading and reading aloud of German words and pseudowords were used in a PET study using (15O) butanol to examine the neural correlates of reading and of the phonological conversion of legal letter strings, with or without meaning. The results of 11 healthy, right-handed volunteers in the age range of 25 to 30 years showed activation of the lingual gyri during silent reading in comparison with viewing a fixation cross. Comparisons between the reading of words and pseudo-words suggest the involvement of the middle temporal gyri in retrieving both the phonological and semantic code for words. The reading of pseudowords activates the left inferior frontal gyrus, including the ventral part of Broca's area, to a larger extent than the reading of words. This suggests that this area might be involved in the sublexical conversion of orthographic input strings into phonological output codes. (Pre)motor areas were found to be activated during both silent reading and reading aloud. On the basis of the obtained activation patterns, it is hypothesized that the articulation of high-frequency syllables requires the retrieval of their concomitant articulatory gestures from the SMA and that the articulation of low-frequency syllables recruits the left medial premotor cortex

Multi-wavelength optical pickup with diffractive optical elements

A novel, to our knowledge, multi-wavelength diffractive optical pickup is presented. The pickup enables multi-focus imaging and increases the data transfer rate considerably. Parallel reading of two or more memory layers is possible. The different spots can be controlled independently. The optical pickup consists of different diffractive optical elements (DOEs). The measured full-width at half-maximum (FWHM) spot intensity for the DOE-pickup is 0.76 mu m-close to the diffraction limited predicted value of 0.71 mu m-indicating good optical performance. The measured highest diffraction efficiencies of the realized DOEs are about 92%

Bi-directional photonic integrated transceivers for optical communication systems

Bi-directional, full duplex transceiver InP/GaInAsP PIC architectures with high crosstalk suppression ratio values for single and dual spectral window operation (1.3 mu m and 1.5 mu m) are reported as well as simulation calculations and preliminary experimental results on their subcomponents

Highly efficient InP-based narrowband photodetectors for 40 to 85 GHz linear high power applications

The fabrication and characterization of InP-based narrowband photodetector OEICs and modules, covering the frequency range 38-90 GHz, is reported. The reverse bias tuneable detectors exhibit 0.55A/W peak responsivities at 80 GHz, equal to the DC value

40 Gbit/s photoreceiver modules comprising InP-OEICs for RZ and NRZ coded TDM system applications

40-Gbit/s photoreceiver modules for 1.55- mu m TDM system applications covering RZ and NRZ coding are described. The modules contain an InP-OEIC with a monolithic integration of a waveguide-integrated photodiode and a traveling-wave amplifier