A compact multi-aperture lens system consists of separate units deployed on a bendable substrate. Each unit includes a fast lens and wobbling sensor which allow high resolution image over a limited field of view.
Due to their negative permittivity, plasmonic materials have found increasing number of applications in advanced photonic devices and metamaterials, ranging from visible wavelength through microwave spectrum. In terms of intrinsic loss and permittivity dispersion, however, limitations on available plasmonic materials remain a serious bottleneck preventing practical applications of a few novel nano-photonic device and metamaterial concepts in visible and nearinfrared spectra. To overcome this obstacle, efforts have been made and reported in literature to engineer new plasmonic materials exploring metal alloys, superconductors, graphene, and heavily doped oxide semiconductors. Though promising progress in heavily doped oxide semiconductors was shown in the near-infrared spectrum, there is still no clear path to engineer new plasmonic materials in the visible spectrum that can outperform existing choices noble metals, e.g. gold and silver, due to extremely high free electron density required for high frequency plasma response. This study demonstrates a path to engineer new plasmonic materials in the visible spectrum by significantly altering the electronic properties in existing noble metals through high density charging/discharging and its associated strong local bias effects. A density functional theory model revealed that the optical properties of thin gold films (up to 7 nm thick) can be altered significantly in the visible, in terms of both plasma frequency (up to 12%) and optical permittivity (more than 50%). These corresponding effects were observed in our experiments on surface plasmon resonance of a gold film electrically charged via a high density double layer capacitor induced by a chemically non-reacting electrolyte.
We derive a light-intensity-dependent dielectric constant for gain medium based on
the conventional rate equation model. A scattering-matrix method in conjunction with
an efficient iteration procedure is proposed to simulate photonic crystal lasers (PCLs).
The light output vs pumping (L-I) curve, lasing mode profile, and chirping effect of
lasing wavelength can be calculated. We check our method in a 1D DBR laser and the
L-I curve agrees well with results by the rate equation model. Our method can be
extended to 3D systems. More complex 2D and 3D PCLs will be simulated in the
The planewave based transfer matrix method has been developed with rational function interpolation to efficiently simulate photonic crystal devices. Cavities embedded in three-dimensional layer-by-layer photonic crystal are systematically studied as an example to show the power of transfer matrix method with the relation between resonant frequencies and the cavity size obtained.
We have demonstrated that the addition of surfactant to developer results in (1) the resolution of the contact holes as small as 0.30 micrometers with good dimension correlation, (2) an increase in the depth of focus at the minimum feature size, and (3) a reduction in the exposure energy needed to form fine patterns. The surfactant enhances the wettability of the developer to the photoresist, thus promoting dissolution of the photoresist, especially in narrow spaces such as contact holes. The optimal surfactant concentration in the developer performs superior development characteristics. In addition, we also demonstrate the effect of the molecular structure of surfactant on development performance.