- Full text PDF available (3)
We realized a tunable continuous-wave terahertz source with megahertz frequency resolution. The system is based on optical heterodyning of two near-infrared distributed feedback diode lasers, each laser being stabilized by electronic feedback from a low-finesse quadrature interferometer. The control loop permits precisely linear laser frequency scans over… (More)
This paper presents a novel framework for implementing portable and scalable data-intensive applications on reconfigurable hardware. Instead of using expensive “reconfigurable supercomputers”, we focus our work on standard PCs and PCI-Express extension cards featuring Field-Programmable Gate Arrays (FPGAs) and memory. In our framework, we… (More)
We report on a calibration procedure that enhances the precision of an interferometer based frequency stabilization by several orders of magnitude. For this purpose, the frequency deviations of the stabilization are measured precisely by means of a frequency comb. This allows us to implement several calibration steps that compensate different systematic… (More)
A mode-hop-free tunable external-cavity Littrow diode laser with intracavity acousto-optic modulators (AOMs) has been built. The modes of the red laser diode without a special antireflection coating are shifted by varying the injection current. The external resonator modes and the grating selectivity are independently electrically alterable by two AOMs.… (More)
The optical properties and stress in thin films of aluminum nitride have been studied as a function of ion energy and the ion-to-vapor arrival ratio (J(i)/J(v)) for the N(2)(+) ion-assisted deposition of aluminum. The ion energy was varied between 75 and 1000 eV. The refractive index was found to depend on the ion energy and flux. The highest index was 2.10… (More)
This paper presents our approach for making FPGA accelerators accessible to software (SW) programmers. It is intended as a starting point for collaborations with other groups pursuing similar objectives. We report on our current SAccO platform (Scalable Accelerator platform Osnabr\"uck) and the planned project extending this platform.
We report on a calibration procedure that enhances the precision of an interferometer based frequency stabilization by several orders of magnitude. For this purpose the frequency deviations of the stabilization are measured precisely by means of a frequency comb. This allows to implement several calibration steps that compensate different systematic errors.… (More)