Computational and experimental investigations on a tuneable spatial heterodyne spectrometer

Spatial heterodyne spectrometers (SHS) are interference based instruments for obtaining spectroscopic information in the UV and visible ranges. In this current study we are representing our experimental and computational findings about a tuneable SHS instrument

Generation of high-order harmonics with tunable photon energy and spectral width using double pulses

This work theoretically investigates high-order harmonic generation in rare-gas atoms driven by two temporally delayed ultrashort laser pulses. Apart from their temporal delay, the two pulses are identical. Using a single-atom model of the laser-matter interaction it is shown that the photon energy of the generated harmonics is controllable within the range of one eV-a bandwidth comparable to the photon energy of the fundamental field-by varying the time delay between the generating laser pulses. It is also demonstrated that high-order harmonics generated by double pulses have advantageous characteristics, which mimick certain properties of an extreme ultraviolet monochromator. With the proposed method, a simpler setup at a much lower cost and comparatively higher spectral yield can be implemented in contrast to other approaches

Raman analysis of diamond-like carbon films deposited onto corrosion resistant alloys used for coronary stent fabrication

The structure of diamond-like carbon thin films prepared by radio frequency chemical vapor deposition onto the surface of different corrosion resistant alloys (304, 316L and Iconel 617) used for coronary stent fabrication was investigated by Raman spectroscopy excited by visible (488 nm) and near-infrared (785 nm) light. The effect of electrochemical polishing of the alloy surface and that of Ar(+) ion pre-treatment on the structure of the forming film was also studied in case of substrate made of 316L material. It was found that in spite of simultaneous preparation the character of the formed amorphous carbon films depends on the type of the alloy. The layer developed on the surface of Fe-rich stainless steels (316L and 304) showed the most diamond-like character, while the Ni-rich Inconel alloy promoted the formation of layer with high graphitic sp2 cluster content. The Ar+ pre-treatment enhanced the adhesion and the diamond-like properties of the film while the electrochemical polishing was found to be unfavorable concerning the diamond-like character of the layer

Double-pulse characterization by self-referenced spectral interferometry

The reconstruction of ultrashort optical pulses with a complex intensity substructure is demonstrated using the Self-Referenced Spectral Interferometry (SRSI) pulse characterization technique with a modified phase retrieval algorithm. A correction spectral phase term is extracted by the manipulation of the temporal interferogram, allowing the treatment of scenarios with complicated pulse shapes, where the original algorithm fails. The improved SRSI algorithm is verified through the application on two temporally well-separated pulses having the same polarization direction and spectral shape, generated by duplicating 37 fs-long amplified pulses of a Ti:Sa based laser system. The spectral phase of highly chirped double pulses with equal or different amplitude ratios is numerically retrieved. The collinear and achromatic experimental arrangement results in a compact and easy-to-align system. Published under license by AIP Publishing