Time domain beam propagation method for the simulation of temporal solitons in periodic media

A time domain beam propagation method for the simulation of optical pulses propagating through Kerr-nonlinear structures is presented. The method is verified by simulation of the known solitary wave solutions in nonlinear periodic medi

Light Turning Mirrors in SiON Optical Waveguides for Hybrid Integration with CMOS Photo-detectors

A new method is proposed for hybrid integration of SiON optical waveguides and standard CMOS photo-detectors based on anisotropic etching of 45° facets in a Si substrate. After removal of anisotropically etched Si structures in cladding SiO2, the fabricated total-internal-reflection mirrors can direct the output of the waveguides to photo-detectors placed on top of the chip. The metal-free fabrication process, designed to create these mirrors, is convenient for batch production. Fourier optics based simulations predict that the reflection efficiency of the mirrors is 68.5 %. The far field pattern obtained from the fabricated device is similar to the simulated one

45° light turning mirrors for hybrid integration of silica optical waveguides and photo-detectors

For hybrid integration of an optical chip with an electronic chip with photo diodes and electronic processing, light must be coupled from the optical chip to the electronic chip. This paper presents a method to fabricate metal-free 45° quasi-total internal reflecting mirrors in optical chips that enable 90° out-of-plane light coupling between flip-chip bonded chips. This method is fully compatible with fabrication of conventional optical chips. The mirrors are created using anisotropic etching of 45° facets in a Si substrate followed by fabrication of optical structures. After removal of the mirror-defining Si structures by isotropic etching, the obtained air-optical structure interface directs the output of the waveguides to out-of-plane photo detectors that are mounted flip-chip on the optical chip. Simulations show a reflection efficiency of 72.3 %, while experimentally 47% was measured on a not fully optimized first batch

The Electron Glass in a Switchable Mirror: Relaxation, Aging and Universality

The rare earth hydride YH$_{3-\delta}$ can be tuned through the metal-insulator transition both by changing $\delta$ and by illumination with ultraviolet light. The transition is dominated by strong electron-electron interactions, with transport in the insulator sensitive to both a Coulomb gap and persistent quantum fluctuations. Via a systematic variation of UV illumination time, photon flux, Coulomb gap depth, and temperature, we demonstrate that polycrystalline YH$_{3-\delta}$ serves as a model system for studying the properties of the interacting electron glass. Prominent among its features are logarithmic relaxation, aging, and universal scaling of the conductivity

An algorithm to detect blends with eclipsing binaries in planet transit searches

We present an algorithm that can detect blends of bright stars with fainter, un-associated eclipsing binaries. Such systems contaminate searches for transiting planets, in particular in crowded fields where blends are common. Spectroscopic follow-up observations on large aperture telescopes have been used to reject these blends, but the results are not always conclusive. Our approach exploits the fact that a blend with a eclipsing binary changes its shape during eclipse. We analyze original imaging data from the Optical Gravitational Lensing Experiment (OGLE), which were used to discover planet transit candidates. Adopting a technique developed in weak gravitational lensing to carefully correct for the point spread function which varies both with time and across the field, we demonstrate that ellipticities can be measured with great accuracy using an ensemble of images. Applied to OGLE-TR-3 and OGLE-TR-56, two of the planetary transit candidates, we show that both systems are blended with fainter stars, as are most other stars in the OGLE fields. Moreover, while we do not detect shape change when TR-56 undergoes transits, TR-3 exhibits a significant shape change during eclipses. We therefore conclude that TR-3 is indeed a blend with an eclipsing binary, as has been suggested from other lines of evidence. The probability that its shape change is caused by residual systematics is found to be less than 0.6%. Our technique incurs no follow-up cost and requires little human interaction. As such it could become part of the data pipeline for any planetary transit search to minimize contamination by blends. We briefly discuss its relevance for the Kepler mission and for binary star detection.Comment: Submitted to ApJ, 10 pages, 10 figure

Metal-insulator transition in YHx: scaling of the sub-THz conductivity

The established scaling laws of the conductivity with temperature and doping are strong indications for the quantum nature of the metal-insulator transition in YH$_x$. Here we report the first results on the frequency scaling of the conductivity. Samples were brought from the insulating to the metallic phase by carrier doping via illumination. In the metallic phase, the sub-terahertz conductivity coincides with the dc data. These results do not agree with the simplest picture of a quantum-phase transition.Comment: 4 pages, accepted to PR

High pressure hydrogen loading cell for photoconductivity measurements down to the milliKelvin regime

A gas loading cell has been developed to load rare earth thin film samples with hydrogen at pressures up to 200 bars at room temperature. A miniature valve closes the gas inlet, after which the cell is suspended from the cold tail of a ^3He flow cryostat into the bore of a 16 T superconducting magnet. An ultraviolet stroboscope outside the cryostat illuminates the sample by way of an optical fiber to a window in the cell. Electrical feedthroughs permit photoconductivity and magnetotransport measurements over three decades in temperature. Extension to other materials, different gas atmospheres, and helium dilution refrigerator temperatures is straightforward

Short-wavelength out-of-band EUV emission from Sn laser-produced plasma

We present the results of spectroscopic measurements in the extreme ultraviolet (EUV) regime (7-17 nm) of molten tin microdroplets illuminated by a high-intensity 3-J, 60-ns Nd:YAG laser pulse. The strong 13.5 nm emission from this laser-produced plasma is of relevance for next-generation nanolithography machines. Here, we focus on the shorter wavelength features between 7 and 12 nm which have so far remained poorly investigated despite their diagnostic relevance. Using flexible atomic code calculations and local thermodynamic equilibrium arguments, we show that the line features in this region of the spectrum can be explained by transitions from high-lying configurations within the Sn$^{8+}$-Sn$^{15+}$ ions. The dominant transitions for all ions but Sn$^{8+}$ are found to be electric-dipole transitions towards the $n$=4 ground state from the core-excited configuration in which a 4$p$ electron is promoted to the 5$s$ sub-shell. Our results resolve some long-standing spectroscopic issues and provide reliable charge state identification for Sn laser-produced plasma, which could be employed as a useful tool for diagnostic purposes.Comment: 11 pages, 4 figure