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28 Jan 2008

Volume 92, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 041901 (2008); http://dx.doi.org/10.1063/1.2831926 (3 pages)

M. A. Avila, K. Suekuni, K. Umeo, H. Fukuoka, S. Yamanaka, and T. Takabatake
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Determination of the glass transition temperature of photorefractive polymer composites from photoconductivity measurements

José A. Quintana, Pedro G. Boj, José M. Villalvilla, María A. Díaz-García, Javier Ortiz, Luis Martín-Gomis, Fernando Fernández-Lázaro, and Ángela Sastre-Santos

Appl. Phys. Lett. 92, 041101 (2008); http://dx.doi.org/10.1063/1.2830707 (3 pages) | Cited 8 times

Online Publication Date: 28 January 2008

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A method to determine the glass transition temperature (Tg) of photorefractive (PR) polymer composites, based on photoconductivity measurements, is proposed. The composite Tg is identified as the temperature at which a clear change in slope in the Arrhenius plot representation of the photoconductivity is obtained. We demonstrate that for PR polymers, this method is more appropriate than the one generally used, based on differential scanning calorimetry (DSC). For PR composites based on the hole transporting polymer poly(N-vinylcarbazole), the Tg value determined from photoconductivity data is around 30 °C higher than that obtained by DSC.
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64.70.pj Polymers
72.40.+w Photoconduction and photovoltaic effects
42.70.Jk Polymers and organics
42.70.Gi Light-sensitive materials

Simultaneous lasing of interband and intersubband transitions in InAs/AlSb quantum cascade laser structures

K. Ohtani, H. Ohnishi, and H. Ohno

Appl. Phys. Lett. 92, 041102 (2008); http://dx.doi.org/10.1063/1.2838296 (3 pages) | Cited 2 times

Online Publication Date: 28 January 2008

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We show that both interband and intersubband transitions in n-InAs/AlSb quantum cascade laser structures can have sufficient gain to enable simultaneous lasing at the two transitions. High electric fields generate holes, which are necessary for interband lasing in InAs. The doping concentration in the injection parts is shown to be critical for controlling the electric fields in the device, enabling the selection of lasing at the intersubband transition alone (high doping), at the interband transition alone (low doping), and simultaneous lasing at both transitions (intermediate doping).
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Effects of atmospheric turbulence on remote optimal control experiments

J. Extermann, P. Béjot, L. Bonacina, P. Billaud, J. Kasparian, and J.-P. Wolf

Appl. Phys. Lett. 92, 041103 (2008); http://dx.doi.org/10.1063/1.2838308 (3 pages) | Cited 1 time

Online Publication Date: 28 January 2008

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Distortions of ultrashort laser pulses propagating through turbulence are investigated both experimentally and numerically. As expected, a strong correlation is found between temporal distortions and local intensity on the speckle pattern. We suggest that the localization of distortions in low-intensity regions may favor remote control strategies based on nonlinear interactions with respect to those based on linear schemes.
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92.60.Ta Electromagnetic wave propagation
92.60.hk Convection, turbulence, and diffusion

Optimizing optical absorption of TiO2 by alloying with TiS2

Naoto Umezawa, Anderson Janotti, Patrick Rinke, Toyohiro Chikyow, and Chris G. Van de Walle

Appl. Phys. Lett. 92, 041104 (2008); http://dx.doi.org/10.1063/1.2835707 (3 pages) | Cited 6 times

Online Publication Date: 28 January 2008

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TiO2 is an attractive material for photocatalytic water splitting, but its band gap is too large to allow for efficient absorption of solar photons. We present a comprehensive first-principles investigation of band-structure modifications induced by alloying TiO2 with TiS2. The band gap of TiO2(1−x)S2x alloys exhibits a dramatic decrease upon addition of even a low concentration of S. The optical absorption of visible light is attainable with sulfur concentrations less than x = 0.25. We have verified that the band alignment in these alloys is favorable for photocatalytic applications: in particular, the conduction band exhibits only small shifts, while the majority of the band-gap change is due to an upward shift of the valence band.
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78.40.Fy Semiconductors
71.20.Nr Semiconductor compounds
82.50.-m Photochemistry

Fabrication of graded index waveguides in azo polymers using a direct writing technique

Hamidreza Karimi–Alavijeh, Gholam-Mohammad Parsanasab, Mohammad-Amin Baghban, Edris Sarailou, Alireza Gharavi, Sirus Javadpour, and Vladimir Shkunov

Appl. Phys. Lett. 92, 041105 (2008); http://dx.doi.org/10.1063/1.2838341 (3 pages) | Cited 6 times

Online Publication Date: 28 January 2008

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Fast direct writing of waveguides on polymers using low power continuous-wave lasers has been investigated. Using the cis-trans property of a functionalized sulfonated azo chromophores, we have fabricated graded index waveguides with low loss, which is due to graded index sidewalls. Fabrication is done by exposing the polymer film to a 532 nm wavelength laser beam focused to about 5 μm spot at the film. Losses were calculated to be 0.48±0.04 dB/cm at 830 nm wavelength with no surface deformation. This technique enables us to fabricate integrated optical circuits including directional couplers, dividers, filters, switches, etc., as they are currently investigated in our laboratory.
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42.79.Gn Optical waveguides and couplers
42.79.Ry Gradient-index (GRIN) devices

Quantitative analysis of Kerr nonlinearity and Kerr-like nonlinearity induced via terahertz generation in ZnTe

Zhen Tian, Changlei Wang, Qirong Xing, Jianqiang Gu, Yanfeng Li, Mingxia He, Lu Chai, Qingyue Wang, and Weili Zhang

Appl. Phys. Lett. 92, 041106 (2008); http://dx.doi.org/10.1063/1.2838446 (3 pages) | Cited 2 times

Online Publication Date: 29 January 2008

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Kerr nonlinearity and Kerr-like nonlinearity induced via terahertz generation and the electro-optical effect in ZnTe crystal are investigated. In general, these nonlinear effects are concomitant and difficult to quantitatively analyze in the time domain. Even Z-scan technique, which is a simple and sensitive single-beam method to determine both the sign and magnitude of the nonlinear refractive index as well as the nonlinear absorption coefficient of a given material, cannot quantitatively analyze the contribution of each nonlinear effect directly. A method is proposed in the spectral domain to distinguish between Kerr nonlinearity and Kerr-like nonlinearity. Experimental results agree with theoretical analysis.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Mp Nonlinear optical crystals
78.20.Jq Electro-optical effects
78.66.Hf II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Storage and selective release of optical information based on fractional stimulated Raman adiabatic passage in a solid

Hai-Hua Wang, Lei Wang, Xiao-Gang Wei, Ya-Juan Li, Dun-Mao Du, Zhi-Hui Kang, Yun Jiang, and Jin-Yue Gao

Appl. Phys. Lett. 92, 041107 (2008); http://dx.doi.org/10.1063/1.2838731 (3 pages) | Cited 2 times

Online Publication Date: 30 January 2008

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We demonstrate storage and selective release of a light pulse in a Pr:YSO crystal, which is based on atomic spin coherence created by fractional stimulated Raman adiabatic passage (STIRAP). The fractional STIRAP gives better storage fidelity compared to STIRAP. Selective release of stored optical information and better storage fidelity have practical applications in information processing and all-optical communication.
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42.30.-d Imaging and optical processing
42.79.Vb Optical storage systems, optical disks
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.70.Mp Nonlinear optical crystals

Vibrational dephasing time imaging by time-resolved broadband coherent anti-Stokes Raman scattering microscopy

Young Jong Lee and Marcus T. Cicerone

Appl. Phys. Lett. 92, 041108 (2008); http://dx.doi.org/10.1063/1.2838750 (3 pages) | Cited 17 times

Online Publication Date: 30 January 2008

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Time delay control in broadband coherent anti-Stokes Raman scattering (CARS) allows acquisition of time-resolved CARS images free of nonresonant background (NRB). We demonstrate that, in some cases, CARS image contrast is not chemical contrast but simply due to differences in NRB. Time-resolved CARS is used to rectify this by eliminating the NRB. We also construct a vibrational dephasing time image from a sequence of time-resolved CARS images of polystyrene beads in toluene. In doing so, we demonstrate the potential of imaging local molecular interactions between molecules and their surrounding in a structured medium.
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07.60.Pb Conventional optical microscopes
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering

Direct write of microlens array using digital projection photopolymerization

Yi Lu and Shaochen Chen

Appl. Phys. Lett. 92, 041109 (2008); http://dx.doi.org/10.1063/1.2838751 (3 pages) | Cited 9 times

Online Publication Date: 30 January 2008

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Microlens array is a key element in the field of information processing, optoelectronics, and integrated optics. Many existing fabrication processes remain expensive and complicated even though relatively low-cost replication processes have been developed. Here, we demonstrate the fabrication of microlens arrays through projection photopolymerization using a digital micromirror device (DMD) as a dynamic photomask. The DMD projects grayscale images, which are designed in a computer, onto a photocurable resin. The resin is then solidified with its thickness determined by a grayscale ultraviolet light and exposure time. Therefore, various geometries can be formed in a single-step, massively parallel fashion. We present microlens arrays made of acrylate-based polymer precursor. The physical and optical characteristics of the resulting lenses suggest that this fabrication technique is potentially suitable for applications in integrated optics.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Bh Lenses, prisms and mirrors
42.82.Et Waveguides, couplers, and arrays
42.70.Jk Polymers and organics
82.35.-x Polymers: properties; reactions; polymerization
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Enhanced broadband near-infrared luminescence in transparent silicate glass ceramics containing Yb3+ ions and Ni2+-doped LiGa5O8 nanocrystals

Botao Wu, Jian Ruan, Jinjun Ren, Danping Chen, Congshan Zhu, Shifeng Zhou, and Jianrong Qiu

Appl. Phys. Lett. 92, 041110 (2008); http://dx.doi.org/10.1063/1.2839333 (3 pages) | Cited 10 times

Online Publication Date: 30 January 2008

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Spectral properties of Yb3+/Ni2+ codoped transparent silicate glass ceramics containing LiGa5O8 nanocrystals were investigated. The near-infrared emission intensity of Ni2+ was largely increased with Yb3+ codoping due to Yb3+→Ni2+ energy transfer. The qualitative calculation of the energy transfer constant Cs-a and rate Ps-a showed that the Yb3+→Ni2+ energy transfer was much greater than in the opposite direction. Yb3+/Ni2+ codoped glass ceramics with 0.75 mol % Yb2O3 exhibited a near-infrared emission with full width at half maximum of 290 nm and fluorescent lifetime of 920 μs. The glass ceramics are promising for broadband optical amplification.
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78.30.Hv Other nonmetallic inorganics
78.55.Hx Other solid inorganic materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Toward tunable light propagation and emission in thin nanostructured plasmonic waveguides

Cyrille Billaudeau, Stéphane Collin, Fabrice Pardo, Nathalie Bardou, and Jean-Luc Pelouard

Appl. Phys. Lett. 92, 041111 (2008); http://dx.doi.org/10.1063/1.2838348 (3 pages) | Cited 1 time

Online Publication Date: 30 January 2008

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High-resolution angle-resolved transmission measurements are carried out through nanostructured plasmonic waveguides made of thin gold films with very narrow slits deposited on GaAs substrates. They reveal transmission intensity modulations along the air/metal surface plasmon band, due to the presence of metal/substrate surface modes. Two propagation regimes have been identified. In this plasmonic waveguide, the radiative emission can be enhanced or inhibited by a slight modification of the refractive index of the substrate (δn/n ≃ 1%), allowing to control the propagation regime of surface plasmon waves along the air/metal interface.
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42.79.Gn Optical waveguides and couplers
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Fabrication and crystal line patterning of Li1.3Al0.3Ti1.7(PO4)3 ion conductive glass by Ni atom heat processing method

Maolin Pang, Ryota Suzuki, Makoto Saito, Ken-ichi Machida, Hiromasa Hanzawa, Yoshihiro Nojiri, and Shigeo Tanase

Appl. Phys. Lett. 92, 041112 (2008); http://dx.doi.org/10.1063/1.2838355 (3 pages) | Cited 4 times

Online Publication Date: 30 January 2008

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Li1.3Al0.3Ti1.7(PO4)3 conductive crystal lines composed of closely compacted fine particles were patterned on the surface of 13.9Li2O–8.9Al2O3–37.6TiO2–38.6P2O5–1NiO (mol %) precursor glass by a continuous wave Yb fiber laser irradiation (λ = 1078 nm) using the nickel atom heat processing method. Homogeneous and smooth crystal lines with a uniform width of 30 μm were obtained with a laser power of 1.3 W. The Li+ ion conductivity of the laser patterned glass was about two orders of magnitude higher than that of the glass matrix due to the formation of Li1.3Al0.3Ti1.7(PO4)3 conductive crystalline phase by Yb fiber laser irradiation.
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42.62.-b Laser applications
61.82.Ms Insulators
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
66.30.hh Glasses

Transient electromagnetically induced transparency in self-assembled quantum dots

S. Marcinkevičius, A. Gushterov, and J. P. Reithmaier

Appl. Phys. Lett. 92, 041113 (2008); http://dx.doi.org/10.1063/1.2840160 (3 pages) | Cited 15 times

Online Publication Date: 31 January 2008

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A coherent absorption dip in pump-probe experiment performed on a ten layer optically thin InGaAs/GaAs quantum dot (QD) structure has been observed. Measurements performed for different wavelengths, polarizations, pulse widths, and temperatures allow assigning the dip to electromagnetically induced transparency (EIT). The EIT scheme is based on coupling of excitons with different spins in asymmetric QDs. Using spectrally narrow pulses, detrimental effect of the inhomogeneous broadening is reduced since only the QDs with transitions resonant with the pulse wavelength are addressed and participate in the EIT. The effect has been observed at temperatures up to 140 K.
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78.67.Hc Quantum dots
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.21.La Quantum dots
71.35.-y Excitons and related phenomena

Valence band structure of AlN probed by photoluminescence

A. Sedhain, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 92, 041114 (2008); http://dx.doi.org/10.1063/1.2840176 (3 pages) | Cited 2 times

Online Publication Date: 31 January 2008

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Deep ultraviolet photoluminescence (PL) was employed to probe the valence band structure of AlN epilayers grown by metal organic chemical vapor deposition on c-plane sapphire substrates. At 10 K, in addition to the dominant emission peak at 6.050 eV polarized in the E∥c direction, we observed two additional emission peaks at 6.249 and 6.262 eV polarized in the E⊥c direction. These two emission lines are assigned to the recombination of free excitons related to the B and C valence bands. A more comprehensive picture of the valence band structure of AlN is thus directly obtained from the PL measurements.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
71.35.-y Excitons and related phenomena

At a glance determination of laser light polarization state

Riccardo Castagna, Daniele E. Lucchetta, Francesco Vita, Luigino Criante, and Francesco Simoni

Appl. Phys. Lett. 92, 041115 (2008); http://dx.doi.org/10.1063/1.2839321 (3 pages) | Cited 1 time

Online Publication Date: 31 January 2008

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We report a simple technique for the visual determination of a laser light polarization state. The technique is based on a phenomenon occurring when laser light impinges on a particular photopolymerizable mixture sandwiched between two glass plates. After a brief irradiation, some polarization dependent patterns are observed far from the incidence spot. This effect is due to light scattered by the polymerized material and waveguided by the glass. A visual inspection of the characteristic patterns allows an immediate determination of the light polarization. This technique could be conveniently exploited for qualitative and/or quantitative polarimetry, as well as for designing polarization-driven devices.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.70.Jk Polymers and organics
07.60.Fs Polarimeters and ellipsometers
42.15.Eq Optical system design

Gain and continuous-wave laser power enhancement with a secondary discharge to predissociate molecular iodine in an electric oxygen-iodine laser

G. F. Benavides, J. W. Zimmerman, B. S. Woodard, D. L. Carroll, J. T. Verdeyen, T. H. Field, A. D. Palla, and W. C. Solomon

Appl. Phys. Lett. 92, 041116 (2008); http://dx.doi.org/10.1063/1.2839323 (3 pages) | Cited 18 times

Online Publication Date: 31 January 2008

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Herein the authors report on the demonstration of a 50% enhancement in gain and 38% enhancement in continuous-wave laser power on the 1315 nm transition of atomic iodine through the addition of a secondary discharge to predissociate the molecular iodine in an electric oxygen-iodine laser. In the primary discharge the O2(a 1Δ) is produced by a radio-frequency-excited electric discharge sustained in an O2–He–NO gas mixture, and I(2P1/2) is then pumped using energy transferred from O2(a 1Δ). A gain of 0.10% cm−1 was obtained and the total laser output power was 6.2 W.
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42.55.Ks Chemical lasers
42.60.By Design of specific laser systems
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
52.80.Pi High-frequency and RF discharges
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Pk Continuous operation

Gain-induced switching in metal-dielectric-metal plasmonic waveguides

Zongfu Yu, Georgios Veronis, Shanhui Fan, and Mark L. Brongersma

Appl. Phys. Lett. 92, 041117 (2008); http://dx.doi.org/10.1063/1.2839324 (3 pages) | Cited 28 times

Online Publication Date: 31 January 2008

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The authors show that the incorporation of gain media in only a selected device area can annul the effect of material loss and enhance the performance of loss-limited plasmonic devices. In addition, they demonstrate that optical gain provides a mechanism for on/off switching in metal-dielectric-metal (MDM) plasmonic waveguides. The proposed gain-assisted plasmonic switch consists of a subwavelength MDM plasmonic waveguide side coupled to a cavity filled with semiconductor material. They show that the principle of operation of such gain-assisted plasmonic devices can be explained using a temporal coupled-mode theory.
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42.79.Gn Optical waveguides and couplers
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.82.Et Waveguides, couplers, and arrays
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Optical spin manipulation of electrically pumped vertical-cavity surface-emitting lasers

S. Hövel, A. Bischoff, N. C. Gerhardt, M. R. Hofmann, T. Ackemann, A. Kroner, and R. Michalzik

Appl. Phys. Lett. 92, 041118 (2008); http://dx.doi.org/10.1063/1.2839381 (3 pages) | Cited 13 times

Online Publication Date: 31 January 2008

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We analyze the potential for the spin manipulation of vertical-cavity surface-emitting lasers (VCSELs) by operating them electrically and injecting additional spin-polarized carriers by polarized optical excitation. The output polarization of the VCSELs can be easily controlled by the spin orientation of the optically injected carriers when the injection current does not exceed the threshold current.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Enhancement of ZnO light emission via coupling with localized surface plasmon of Ag island film

Peihong Cheng, Dongsheng Li, Zhizhong Yuan, Peiliang Chen, and Deren Yang

Appl. Phys. Lett. 92, 041119 (2008); http://dx.doi.org/10.1063/1.2839404 (3 pages) | Cited 57 times

Online Publication Date: 31 January 2008

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Enhancement of the light emission of ZnO films was observed by coupling through localized surface plasmons. By sputtering Ag islands onto ZnO films, their band gap emission coming through the Ag island films was enhanced by threefolds, while the defect emission was quenched. The enhancement was found to be mainly dependent on the sputtering time of the Ag islands, which is related to the island size. Furthermore, the relative spectral position between the ZnO emission band and the localized surface plasmon resonance bands of Ag islands was found to be decisive for the enhancement or quenching of photoluminescence, indicating that the emission intensity of ZnO films can be controlled by the Ag island size and the localized surface plasmon resonance band position.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.55.-m Photoluminescence, properties and materials
78.66.-w Optical properties of specific thin films
81.15.Cd Deposition by sputtering

Organic-inorganic hybrid transparent materials containing chromium ion-doped forsterite crystals as gain media

Yusuke Arai, Guanshi Qin, Takenobu Suzuki, Yasutake Ohishi, Takao Tani, and Shu Saeki

Appl. Phys. Lett. 92, 041120 (2008); http://dx.doi.org/10.1063/1.2839433 (3 pages)

Online Publication Date: 31 January 2008

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Organic-inorganic hybrid transparent materials containing chromium ion-doped forsterite (Cr:Mg2SiO4) crystals are investigated as gain media. Thin films and bulk samples are prepared by a sol-gel technique. Starting sols for host matrices, which are prepared from diphenyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and titanium tetra-n-butoxide, are mixed with flame spray made Cr:Mg2SiO4 nanocrystals ultrasonically. The hybrid materials containing Cr:Mg2SiO4 with high transparency are realized by matching refractive indices of the host matrices with that of Cr:Mg2SiO4 by controlling starting sols’ composition. A broad emission centered at 1170 nm is confirmed under the excitation at 976 nm.
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.-w Optical properties of specific thin films

Thermal stress analysis of a Nd:YVO4 laser medium end pumped by a Gaussian beam

Xiulan Huai and Zhigang Li

Appl. Phys. Lett. 92, 041121 (2008); http://dx.doi.org/10.1063/1.2839591 (2 pages) | Cited 2 times

Online Publication Date: 31 January 2008

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The heat conduction and the thermal stress problems in an orthotropic Nd:YVO4 laser medium end pumped by a Gaussian beam are modeled and analytically solved. The three-dimensional temperature expression is derived via an integral transform method, and the thermal stress field is deduced by Airy’s thermal stress function method, utilizing said three-dimensional temperature expression, based on the plain-strain assumption. The results indicate that the orthotropic thermal properties have significant influence on the thermal strain pattern, but have less effect on the thermal stress profile in the absence of external forces.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.70.Hj Laser materials
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
02.30.Uu Integral transforms

Effective-medium models and experiments for extraordinary transmission in metamaterial-loaded waveguides

Hao Xu, Zhiyu Wang, Jiaming Hao, Jiajie Dai, Lixin Ran, J. A. Kong, and L. Zhou

Appl. Phys. Lett. 92, 041122 (2008); http://dx.doi.org/10.1063/1.2840163 (3 pages) | Cited 4 times

Online Publication Date: 1 February 2008

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We show that a metallic waveguide behaves as an electric (magnetic) plasma for transverse-electric (transverse-magnetic) polarized electromagnetic (EM) waves at frequencies below cutoff value. Inserting anisotropic resonance structures of either electric or magnetic type into a waveguide, we find extraordinary transmissions of EM waves with different polarizations through the waveguide at frequencies well below the waveguide’s cutoff value, following two different mechanisms. Microwave experiments, in excellent agreements with finite-different-time-domain simulations, are performed to demonstrate all theoretical predictions.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
84.40.Az Waveguides, transmission lines, striplines
02.70.Bf Finite-difference methods
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Development of 40 MHz inductively coupled plasma source and frequency effects on plasma parameters

Hyun-Su Jun and Hong-Young Chang

Appl. Phys. Lett. 92, 041501 (2008); http://dx.doi.org/10.1063/1.2838306 (3 pages) | Cited 1 time

Online Publication Date: 29 January 2008

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A large-area inductively coupled plasma (ICP) source capable of securing azimuthal plasma uniformity at a 40.00 MHz has been developed. The antenna, referred to as a capacitor distributed resonance antenna, minimizes the azimuthally nonuniform antenna capacitive field with eight distributed vertical capacitors. The antenna was designed to maximize the antenna current using L-C series resonance. Based on plasma diagnostics with a 13.56 MHz conventional ICP, comparative analyses were performed in terms of the plasma density, electron temperature, and frequency characteristics of the electron energy probability function (EEPF). In addition, the frequency dependency of the EEPF was found in the collisional (νen>ω), normal skin [vth/δ⪡(ω2+νen2)1/2] regime and the physical causes of were examined.
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52.50.Dg Plasma sources
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.25.-b Plasma properties
52.70.-m Plasma diagnostic techniques and instrumentation

Extractable, elevated ion charge states in the transition regime from vacuum sparks to high current vacuum arcs

Georgy Yu. Yushkov and André Anders

Appl. Phys. Lett. 92, 041502 (2008); http://dx.doi.org/10.1063/1.2839616 (3 pages) | Cited 6 times

Online Publication Date: 1 February 2008

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Metal ions were extracted from pulsed discharge plasma operating in the transition region between vacuum spark and vacuum arc. At a peak current of about 4 kA, and with a pulse duration of 8 μs, we observed mean ion charges states of about 6 for several cathode materials. In the case of platinum, the highest average charge state was 6.74 with charge states present as high as 10, and with gold we found traces of charge state 11. At higher currents, nonmetallic contaminants started to dominate the ion beam, preventing further enhancement of the metal charge states.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.50.-b Plasma production and heating

Propagation of a femtosecond pulsed laser ablation plume into a background atmosphere

S. Amoruso, R. Bruzzese, X. Wang, and J. Xia

Appl. Phys. Lett. 92, 041503 (2008); http://dx.doi.org/10.1063/1.2839582 (3 pages) | Cited 18 times

Online Publication Date: 1 February 2008

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We investigate the effects of ambient gas on the expansion dynamics of laser plume produced during femtosecond laser ablation of a metallic target. We studied experimentally plume propagation for ambient air pressure ranging from 10−6 to 50 mbar, observing that the atomic and nanoparticles plume components experience different effects. We interpret these results with a simplified model of the plume front propagation, which is able to fully reproduce the main experimental features. Our results allow us to estimate quantitatively the nanoparticles plume content (up to about 80%), and can help identifying optimal conditions of nanoparticles deposition for thin films production.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.38.Mf Laser ablation
52.77.Dq Plasma-based ion implantation and deposition
81.07.Bc Nanocrystalline materials
81.16.Mk Laser-assisted deposition
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