Diamond nanofocusing refractive X-ray lenses made by planar etching technology.

The manufacturing steps and first tests of a refractive lens made of polycrystalline diamond are described. A fabrication process based on electron-beam lithography and deep reactive ion etching is introduced. Experimental tests on beamline ID13 at the ESRF have been performed. A spot size of 360 nm (FWHM) at an energy E = 24.3 keV is observed.

Paradise lost or paradise regained? Changes in admission system affect academic performance and drop-out rates of medical students.

BACKGROUND: The Austrian State medical universities had to change their admission system in 2005. Until this year admission to medical studies was unrestricted. Innsbruck Medical University chose the Eignungstest für das Medizinstudium in der Schweiz (EMS) aptitude test for admission testing. AIMS AND OBJECTIVES: Did the implementation of a selection process affect the academic performance and drop-out rates of students according to gender? METHODS: Two groups of students were compared: 'open admission' (2002-2004), and 'selected' (2006-2009). Academic performance was tested according to results in the final exams after year 1 (SIP 1; SIP, summative integrierte Prüfung) and after year 3 (SIP 3). Drop-out rates were recorded using the registration system of the university. RESULTS: Both, male and female 'selected' students had a higher passing rate regarding SIP 1 and they passed SIP 1 in shorter time and using fewer attempts than the open admission group. The percentage in passing SIP 3 did not change due to change in admission. The drop-out rates were significantly reduced for male and female students. 'Unselected' female students had a significantly higher drop-out ratio than 'unselected' male counterparts. After EMS testing, the drop-out ratios of female and male students were not significantly different. CONCLUSION: Selected applicants were more able and better motivated to study medicine.

Diamond-integrated optomechanical circuits.

Diamond offers unique material advantages for the realization of micro- and nanomechanical resonators because of its high Young's modulus, compatibility with harsh environments and superior thermal properties. At the same time, the wide electronic bandgap of 5.45 eV makes diamond a suitable material for integrated optics because of broadband transparency and the absence of free-carrier absorption commonly encountered in silicon photonics. Here we take advantage of both to engineer full-scale optomechanical circuits in diamond thin films. We show that polycrystalline diamond films fabricated by chemical vapour deposition provide a convenient wafer-scale substrate for the realization of high-quality nanophotonic devices. Using free-standing nanomechanical resonators embedded in on-chip Mach-Zehnder interferometers, we demonstrate efficient optomechanical transduction via gradient optical forces. Fabricated diamond resonators reproducibly show high mechanical quality factors up to 11,200. Our low cost, wideband, carrier-free photonic circuits hold promise for all-optical sensing and optomechanical signal processing at ultra-high frequencies.

Grating-assisted coupling to nanophotonic circuits in microcrystalline diamond thin films.

Synthetic diamond films can be prepared on a waferscale by using chemical vapour deposition (CVD) on suitable substrates such as silicon or silicon dioxide. While such films find a wealth of applications in thermal management, in X-ray and terahertz window design, and in gyrotron tubes and microwave transmission lines, their use for nanoscale optical components remains largely unexplored. Here we demonstrate that CVD diamond provides a high-quality template for realizing nanophotonic integrated optical circuits. Using efficient grating coupling devices prepared from partially etched diamond thin films, we investigate millimetre-sized optical circuits and achieve single-mode waveguiding at telecoms wavelengths. Our results pave the way towards broadband optical applications for sensing in harsh environments and visible photonic devices.