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In this paper, an optical switch based on a microelectromechanical phase modulator is presented. Phase tuning is achieved by tuning the vertical gap between two vertically coupled waveguides through the application of a reverse bias on a p-i-n junction. An effective refractive index tuning Δneff of 0.03 and a phase shift of more than 3π rad at telecom wavelengths are measured with an on-chip Mach–Zehnder interferometer (MZI), with a phase-tuning length of only 140 μm. With a bias voltage of 5.1 V, a half-wave-voltage-length product (Vπ L) of 5.6 × 10−3 V·cm is achieved. Furthermore, optical crossbar switching in a MZI is demonstrated with a 15 dB extinction ratio using an actuation voltage of only 4.2 V. Our work provides a solution to on-chip, low-voltage phase modulation and optical switching. The switch is fabricated on an indium-phosphide membrane on a silicon substrate, which enables the integration with active components (e.g., amplifiers, lasers, and detectors) on a single chip.In this paper, an optical switch based on a microelectromechanical phase modulator is presented. Phase tuning is achieved by tuning the vertical gap between two vertically coupled waveguides through the application of a reverse bias on a p-i-n junction. An effective refractive index tuning Δneff of 0.03 and a phase shift of more than 3π rad at telecom wavelengths are measured with an on-chip Mach–Zehnder interferometer (MZI), with a phase-tuning length of only 140 μm. With a bias voltage of 5.1 V, a half-wave-voltage-length product (Vπ L) of 5.6 × 10−3 V·cm is achieved. Furthermore, optical crossbar switching in a MZI is demonstrated with a 15 dB extinction ratio using an actuation voltage of only 4.2 V. Our work provides a solution to on-chip, low-voltage phase modulation and optical switching. The switch is fabricated on an indium-phosphide membrane on a silicon substrate, which enables the integration with active components (e.g., amplifiers, lasers, and detectors) on a single chip.

For organic solar cells, insertion of an optical spacer between the active layer and the reflective electrode results in a redistribution of the optical electric field. In this paper, theoretical calculations using optical modeling are compared with experimental results for devices with ZnO as optical spacer. An excellent agreement was found for blends composed of poly(3-hexylthiophene) and a fullerene derivative [6,6]-phenyl C61 butyric acid methyl ester.

The paper provides an insight into the development of the micropore damage phenomena during the hydrogen ingress and egress process in a high strength aluminum alloy. For this purpose high resolution micro tomography scans on samples subjected to combinations of cathodic hydrogen charging and de-sorption heat treatment were carried out. From the quantitative analysis, spatial mapping of pores and particles, and a probabilistic evaluation of the 3D datasets it was conclusively shown that the development of micropore damage during hydrogen ingress – egress had a non-trivial dependence on the particle size distribution. This potentially provides rationale to mitigate the deleterious effects of hydrogen in aluminium alloys by controlling particle size and distribution in the matrix.

Tanei H., Kusakabe K., Ogi H., et al. "Observation of Γ-point phonon frequency in ultrathin metallic films confirmed by ab initio calculation and lattice dynamics", Applied Physics Letters, 95(1), 011902 (2009) https://doi.org/10.1063/1.3157138., Vibrations in ultrathin metallic films excited by ultrafast light pulses have been studied based on continuum mechanics. However, this paper shows that they are Γ-point phonon vibrations of plate-phonon modes. Ab initio and lattice dynamics calculations are made to compare Γ-point phonon vibrational frequencies with measurements obtained by the picosecond ultrasound spectroscopy. The standing-wave frequencies of specific Γ-point phonon modes of the slab model show good agreement with measurements without any fitting parameters. This study informs us of a limitation of the continuum-mechanics theory for explaining the mechanics of ultrathin metallic films. © 2009 American Institute of Physics.

The use of photoluminescence excited with two-photon process for characterizing the defect and impurity level in wide-gap semiconductor is discussed in this paper. Defects of polycrystalline zinc selenide (ZnSe) is observed deep inside the crystal. Two types of defects can be detected based on the spectral luminescence image. One type of defect can be seen in the entire spectrum images. Meanwhile, other types of defects can only be observed at higher energy of the spectrum, from 460to465nm. This study represents works of identifying crystals defect in wide gap materials by two-photon luminescence technique.

Under the guidance of the calculation of phase diagrams method, the self-organized Cu alloy/stainless steel composite powders with a core/shell microstructure were developed based on the gas atomization process, and the formation evolution of self-organized core/shell structure composite powders was modeled by the phase field method. This paper gives a more detailed explanation for the formation of self-organized core/shell structure composite powders from the viewpoints of thermodynamics and kinetics. Such core/shell structure composite powders have good combination of high strength and corrosion resistance (Fe-rich phase) and high electric and thermal conductivities (Cu-rich phase) with many potential advanced applications in electronic devices.

This paper reports a quartz crystal cantilever for piezoelectric vibration sensing in scanning probe microscopy (SPM). SPM imaging by a frequency modulation detection method is demonstrated in ambient atmosphere using a 22.5-μm-thick cantilevered AT-cut quartz crystal with metal electrodes on both sides. The spring constant of the cantilever is calculated to be 10N∕m. Despite the low electromechanical coupling between the piezoelectric effect and the flexural vibration, a high sensitivity of 0.07nm∕(Hz)0.5 to vibration is achieved in the second flexural mode. The cantilever self-oscillates on the basis of piezoelectric detection, and offers short-term stability of within approximately 0.5Hz in ambient atmosphere at room temperature. The force curve of the self-oscillating cantilever shows that the self-oscillation can be sustained even when in contact with a sample.

This paper concerns the use of Brillouin scattering measurements to study lattice attenuation in semiconducting CdS crystals. Measured acoustic fluxes are produced by the acoustoelectric domains. In order to measure the attenuation constant, an ultrasonic injection method is applied. A sample is divided into two parts; one part is used as a generation region of the acoustic flux [region (1)] and the other part is used as a propagation region of the injected flux [region (2)]. The acoustic attenuations of various frequencies are measured at region (2). The lattice attenuation is greatly affected by the rise time of an applied pulse in region (1). It is clear that acoustic flux in the acoustic domain which originates from the amplification of the pure thermally excited acoustic flux attenuates as f2 and is in accordance with the Akhieser loss. On the other hand, a shock-excited acoustic flux attenuates as f ∼1.5.