Volume 89, Issue 10, 04 September 2006
- lasers, optics, and optoelectronics
- plasmas and electrical discharges
- structural, mechanical, thermodynamic, and optical properties of condensed matter
- electronic transport and semiconductors
- magnetism and superconductivity
- dielectrics and ferroelectricity
- nanoscale science and design
- device physics
- interdisciplinary and general physics
Index of content:
Using the plasmon hybridization method the authors examine light-induced coupling between the localized plasmons of a metallic nanosphere and the propagating plasmons of an infinite metallic wire. The plasmon resonances of the coupled system are found to be shifted in frequency relative to the plasmonicstructure of the isolated nanoparticles. The magnitude of the shifts depends on the polarization of the incident light and the system geometry. In the limit of a thin wire, it is shown that the nanosphere can serve as an efficient nanoantenna which can couple incident electromagnetic radiation into low-energy propagating wireplasmons.
- LASERS, OPTICS, AND OPTOELECTRONICS
Single-polarization polarization maintaining optical fiber with large stress birefringence and high homogeneity89(2006); http://dx.doi.org/10.1063/1.2345238View Description Hide Description
A type of high-birefringence polarization maintaining (PM) fiber was designed and fabricated using a modified chemical vapor deposition (MCVD) process. Different from conventional stress-applied PM fibers, the shape of the stress jacket is like a “capsule.” By study of the cross sectional component distribution and a calculation of stress birefringence using the finite element method, the structure and composition of capsule PM fiber were optimized and the hybrid MCVD process was developed. With advantages in homogeneity and temperature performance, capsule fiber has great potential in applications such as fiber gyroscopes, fiber hydrophones, and other optical fiber sensors.
89(2006); http://dx.doi.org/10.1063/1.2345374View Description Hide Description
Coupled-cavity hexagonal ringlike photonic crystal lasers are fabricated as a class of single mode photonic crystal laser light sources. The structures are formed by placing one missing hole nanocavity (H1 type) between each two segments at 60° that form the hexagonal ringlike photonic crystal laser. The H1 cavities act as a mode filter, clamping the frequency of emission of the laser device. The emission frequency in these rings with cavities varies as the filling factor is changed, allowing the tuning of the laser emission. Stable single mode lasing occurs with side mode suppression greater than . This kind of devices may be used as an efficient selective filter of modes and may have important applications in future photonic devices for optical communications and optical sensing.
89(2006); http://dx.doi.org/10.1063/1.2345588View Description Hide Description
Using a generalized Gaussian beam decomposition method the authors determine the propagation of a Laguerre-Gaussian (LG) beam that has passed through a thin nonlinear optical Kerr medium. The orbital angular momentum per photon of the beam is found to be conserved while the component beams change. As an illustration of applications, the authors propose and demonstrate a -scan experiment using a beam and a dye-doped polymerfilm.
89(2006); http://dx.doi.org/10.1063/1.2345912View Description Hide Description
Influence of a controllable scatterer on the lasing properties of an ultralow threshold Raman microlaser89(2006); http://dx.doi.org/10.1063/1.2344938View Description Hide Description
The authors investigate Raman lasing in a spherical high- glass microresonator with the help of a near-field optical scanning probe. Scatteredphotons are utilized to perform mode mapping of both pump and lasing modes. Single mode lasing with a record low threshold of is observed. They investigate the position dependent quenching of the laser emission by the additional loss introduced by the subwavelength scanning probe and derive an estimation of the mechanical force gradient acting on the probe. They generalize a theoretical model of Raman lasing in microresonators to describe these effects.
89(2006); http://dx.doi.org/10.1063/1.2345594View Description Hide Description
Surface plasmon modes, resonantly excited at the two sides of an ultrathin (noble) metal layer in contact with two (nearly) identical dielectric media interact via the overlap of their electromagnetic fields resulting in two new coupled modes, i.e., a short range and a long range surface plasmon (LRSP), respectively. The authors demonstrate that both the enhanced optical field of the LRSP wave at the metal/dielectric interface as well as its increased (evanescent) penetration depth reaching farther into the analyte solution can be used for significant enhancements when using LRSP optics in a fluorescence spectroscopic mode of operation. They demonstrate this for the detection of fluorescence intensities from chromophore labeled proteins bound to the sensor surface matrix.
89(2006); http://dx.doi.org/10.1063/1.2346224View Description Hide Description
A microscopic approach combining rate equations for photon and electron/hole occupations with kinetic equations for Coulomb scattering rates involving quantum dot and wetting layer states in quantum dot lasers is presented. The authors find strong damping of relaxation oscillations on a picosecond to nanosecond time scale depending on the type of the initial perturbation, similar to the damping observed in experiments by various groups. They show that the Coulomb interaction is crucial for an understanding of this characteristic strong damping.
89(2006); http://dx.doi.org/10.1063/1.2347113View Description Hide Description
Time resolved fluorescence emission from erbiumdoped silicate channel waveguides is studied using an established model for homogeneous cooperative upconversion. Each sample was fabricated using only a single sol-gel deposition for each of the core and cladding layers. As a result of the analysis, values of and are reported for the homogeneous cooperative upconversion constant that governs the interaction of homogeneously distributed erbiumions in the state. The values reported here are found to be in agreement with those reported in other predominantly silica based glasses.
High defect mode and laser action in one-dimensional hybrid photonic crystal containing cholesteric liquid crystal89(2006); http://dx.doi.org/10.1063/1.2347114View Description Hide Description
The authors have investigated the optical characteristics of a one-dimensional hybrid photonic crystal (1D HPC) containing cholesteric liquid crystal (CLC) as a defect by theoretical calculation and predicted the appearance of additional modes at the band edges of the CLC defect, whose factor was higher than those of the other defect modes. They have confirmed the appearance of the additional mode experimentally. Single-mode laser action with low pumping threshold was observed in a 1D HPC with a dye-doped CLC defect, which is based on the additional defect mode with a high factor peculiar to the CLC defect having periodic structure.
89(2006); http://dx.doi.org/10.1063/1.2347115View Description Hide Description
A series of InGaN quantum wells(QWs) emitting blue-green, blue, violet, or ultraviolet light was grown on InGaN underlying layers (ULs). The potential fluctuation in these InGaN QWs was carefully measured using time-resolved photoluminescence, taking several steps to reduce the quantum confinement Stark effect. The potential fluctuation of InGaN QWs on InGaN ULs was smaller than that on conventional GaN ULs with the identical emission wavelength. A violet-light-emitting diode using an InGaN UL had the electroluminescence intensity approximately five times higher than the one using a conventional GaN UL under the low injection-current conditions, indicating that an InGaN UL effectively eliminates the nonradiative recombination centers in the InGaN QWs.
Investigation of dark line defects induced by catastrophic optical damage in broad-area AlGaInP laser diodes89(2006); http://dx.doi.org/10.1063/1.2345225View Description Hide Description
The authors present a detailed investigation of defects generated during catastrophic optical damage (COD) in high-power AlGaInP lasers using microphotoluminescence mapping, focused ion beam(FIB) microscopy, and deep-etching techniques. High-resolution images demonstrated that during COD, nonradiative dark line defects (DLDs) originate from the front mirror of the laser and propagate in several branches into the laser perpendicular to the output facet. Furthermore, FIB microscopy identified the epitaxial layers affected by COD, revealing that DLDs are confined to the active region. In addition, deep etching confirmed that these defects have a noncrystalline nature.
89(2006); http://dx.doi.org/10.1063/1.2347700View Description Hide Description
As the system where both space-inversion and time-reversal symmetries are broken simultaneously, the authors have investigated an -doped ferroelectric single crystal under magnetic field, in which the luminescent magnetic ion occupies a noncentrosymmetric site. The -directional dichroism, termed the optical magnetoelectric (OME) effect, was verified in the emission by the reversal of magnetic field and spontaneous polarization. The observed nonreciprocity at implies the possibility of the application of the OME effect to the function of an optical isolator.
89(2006); http://dx.doi.org/10.1063/1.2345251View Description Hide Description
Using a finite difference time domain method, the authors study the electromagnetic transmission coefficient of a microwaveguide coupled to a lateral stub. It is shown that if the stub is covered with a thin metallic layer, the transmission spectrum contains several very narrow and deep depressions despite the small size of the resonator. The frequencies of the zeros of transmission are studied as a function of the geometrical parameters of the stub. The quality factor of the dips is increased when the waveguide is separated from the stub by a small air gap.
Determination of junction temperature in light emitting diodes by self-excited photoluminescence signal89(2006); http://dx.doi.org/10.1063/1.2345587View Description Hide Description
The photoluminescence(PL) of the GaAs substrate excited by the electroluminescence of the active layer is adopted to determine the junction temperature in light emitting diodes. Based on the Varshni equation for GaAs, the temperaturemeasured by this approach is consistent with that obtained by the emission peak energy shift approach. As the PL signal is generated within the substrate, no calibration dependent on the device structure is necessary to determine the junction temperature of the device.
Continuous-wave laser oscillation in subsonic flow on the atomic iodine transition pumped by electric discharge produced89(2006); http://dx.doi.org/10.1063/1.2346134View Description Hide Description
Herein the authors report on the demonstration of a continuous-wave laser in subsonic flow on the transition of atomic iodine using the energy transferred to from produced by a radio-frequency-excited electric discharge. The electric discharge was sustained in an gas mixture. Downstream of the discharge, cold gas injection was employed to raise the gas density and lower the temperature of the continuous gas flow to shift the equilibrium of atomic iodine in favor of the state. The laser output power was in a stable cavity with two 99.993% reflective mirrors.
89(2006); http://dx.doi.org/10.1063/1.2339202View Description Hide Description
Uniform ZnSenanowires are observed on the ablation crater on ZnSe crystal surfaceirradiated by femtosecond lasers in air, while other parts of the sample surface are not polluted. The nanowiregrowth rate is about , it is higher than that fabricated by chemical vapor deposition method by a factor of . The nanowire length and diameter can be controlled by varying laser pulse energy and pulse number. The formation mechanism is studied and found to be self-catalyzed vapor-liquid-solid process.
89(2006); http://dx.doi.org/10.1063/1.2347112View Description Hide Description
The authors demonstrate that optical interference lithography yields diamondphotonic band gap(PBG) architectures with PBGs as large as 25% when the exposed photoresist is replicated with silicon. This process utilizes five linearly polarized beams propagating from the same half-space (umbrella configuration), a setup considerably simpler than the widely studied counterpropagating four-beam setup. Using the umbrella configuration, this diamond structure is also achieved by two or more exposures using fewer interfering laser beams.
89(2006); http://dx.doi.org/10.1063/1.2347117View Description Hide Description
In order to demonstrate silica nanomachining, the authors fabricated line-and-space contact masks with spaces of 53 and on silica glass plates, followed by irradiation with laser plasma softx rays (LPSXs) with wavelengths around . Trenches with the narrowest width of and an aspect ratio of were fabricated by the LPSX irradiation through the contact masks. It was also clarified that silica glass can be machined by irradiation with LPSXs in the wavelength range of in Ar gas which was used as an x-ray bandpass filter.
Control of gray scale inversion in a film-compensated twisted nematic liquid crystal display using beam steering optical film89(2006); http://dx.doi.org/10.1063/1.2345248View Description Hide Description
Commercially available, twisted nematic (TN), liquid crystal cells have intrinsic problems such as light leakage in the dark state, gray scale inversion, and brightness nonuniformity in gray scales when the viewing direction deviates from the normal axis. Film compensation of a TN cell has solved the first problem but the second remains unsolved, which has hindered its applications to large displays. This letter proposes the use of a beam steering film to prepare a TN cell free of gray scale inversion in wide viewing directions.
89(2006); http://dx.doi.org/10.1063/1.2348741View Description Hide Description