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17 Apr 2006

Volume 88, Issue 16, Articles (16xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 88, 163101 (2006); http://dx.doi.org/10.1063/1.2195530 (3 pages)

N. Néel, J. Kröger, and R. Berndt
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Temperature-dependent shifts of three emission bands for ZnO nanoneedle arrays

Bingqiang Cao, Weiping Cai, and Haibo Zeng

Appl. Phys. Lett. 88, 161101 (2006); http://dx.doi.org/10.1063/1.2195694 (3 pages) | Cited 80 times

Online Publication Date: 17 April 2006

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The photoluminescence properties of ZnO nanoneedle arrays, grown on silicon substrate by electrodeposition, are studied over the temperatures from 10 K to 300 K. There exist three emission bands in ultraviolet, violet, and green regions, respectively. With increasing temperature, these bands show different temperature dependences: A normal redshift for the ultraviolet emission, S-shaped shift for the violet emission, and blueshift for the green one. The origins of these three bands and their temperature-dependent shifts are explained based on defect levels (zinc interstitial and oxygen vacancy levels) and carrier localization effect at the defect levels in addition to band-gap shrinkage.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
61.72.J- Point defects and defect clusters

Enhanced emission from Si-based light-emitting diodes using surface plasmons

S. Pillai, K. R. Catchpole, T. Trupke, G. Zhang, J. Zhao, and M. A. Green

Appl. Phys. Lett. 88, 161102 (2006); http://dx.doi.org/10.1063/1.2195695 (3 pages) | Cited 81 times

Online Publication Date: 17 April 2006

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Excitation of surface plasmons on metallic nanoparticles has potential for increasing the absorption and emission from thin Si devices. We report an eight-fold enhancement in electroluminescence from silicon-on-insulator light-emitting diodes at 900 nm via excitation of surface plasmon resonance in silver nanoparticles, along with a redshift in the electroluminescence by 70 nm by overcoating the nanoparticles with ZnS. The enhancement is due to coupling between the electromagnetic excitations of the silver nanoparticles and the waveguide modes.
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85.60.Jb Light-emitting devices
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.22.Lp Collective excitations
78.66.Bz Metals and metallic alloys
78.60.Fi Electroluminescence

High-power and high-efficiency midwave-infrared interband cascade lasers

C. L. Canedy, W. W. Bewley, J. R. Lindle, C. S. Kim, M. Kim, I. Vurgaftman, and J. R. Meyer

Appl. Phys. Lett. 88, 161103 (2006); http://dx.doi.org/10.1063/1.2195778 (3 pages) | Cited 40 times

Online Publication Date: 17 April 2006

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A ten-stage interband cascade laser emitting at 3.3–3.6 μm exhibits a voltage drop only 4% above the theoretical minimum, and operates to room temperature in pulsed mode. At 78 K, a five-stage device mounted epitaxial-side-up with coated facets has a maximum cw wallplug efficiency of 21%, and a second device produces up to 1.1 W of cw power.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Pixel-isolation walls of liquid crystal display formed by fluorinated UV-curable polymers

Jong-In Baek, Jong-Ha Shin, Min-Cheol Oh, Jae Chang Kim, and Tae-Hoon Yoon

Appl. Phys. Lett. 88, 161104 (2006); http://dx.doi.org/10.1063/1.2195902 (3 pages) | Cited 11 times

Online Publication Date: 17 April 2006

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A pixel isolation wall of liquid crystal display is fabricated by utilizing the excellent phase separation between liquid crystal molecules and fluorinated UV-curable polymers. Due to the strong immiscibility of the fluorinated monomers, the segregation of the material occurs effectively to form a polymer wall during the UV exposure. Twisted nematic liquid crystal cells with fluorinated polymer wall are fabricated for the comparison with other devices made of ordinary polymer wall. The fluorinated polymer wall device exhibits enhancement of contrast due to the suppression of the light leakage through the polymer wall as well as reduced saturation voltage by anchoring enhancement.
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42.79.Kr Display devices, liquid-crystal devices
42.70.Jk Polymers and organics
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Surface plasmon-polariton mediated emission from phosphorescent dendrimer light-emitting diodes

C. J. Yates, I. D. W. Samuel, P. L. Burn, S. Wedge, and W. L. Barnes

Appl. Phys. Lett. 88, 161105 (2006); http://dx.doi.org/10.1063/1.2193795 (3 pages) | Cited 18 times

Online Publication Date: 17 April 2006

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We present experimental results showing electroluminescence from a dendrimer based organic light-emitting diode (OLED) mediated via surface plasmon polariton (SPP) modes. A combination of angle dependent electroluminescence, photoluminescence, and reflectance measurements is used to identify emission originating from the guided modes of the device. It is found that the SPP modes, which are usually nonradiative, are coupled to light by a wavelength scale periodic microstructure. It is demonstrated that the necessary microstructure can be readily fabricated by solvent-assisted micromoulding. Our results indicate that such an approach may offer a means to increase the efficiency of dendrimer based OLEDs.
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85.60.Jb Light-emitting devices

Ultracompact cladding-pumped 35-mm-short fiber laser with 4.7-W single-mode output power

L. Li, A. Schülzgen, V. L. Temyanko, M. M. Morrell, S. Sabet, H. Li, J. V. Moloney, and N. Peyghambarian

Appl. Phys. Lett. 88, 161106 (2006); http://dx.doi.org/10.1063/1.2196053 (2 pages) | Cited 13 times

Online Publication Date: 17 April 2006

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We report on ultracompact cladding-pumped fiber lasers, fabricated from single-mode phosphate glass microstructured optical fibers, with several watts of cw output at 1.5 μm. A maximum cw output power of 4.7 W has been achieved from a fiber laser that is only 35 mm in length, corresponding to a yield of 1.34 W/cm of active microstructured fiber.
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42.55.Wd Fiber lasers
42.60.By Design of specific laser systems

Monolithically integrated optical modulator based on polycrystalline Ba0.7Sr0.3TiO3 thin films

Zhimou Xu, Masato Suzuki, Yuichiro Tanushi, and Shin Yokoyama

Appl. Phys. Lett. 88, 161107 (2006); http://dx.doi.org/10.1063/1.2197288 (3 pages) | Cited 5 times

Online Publication Date: 17 April 2006

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Good-quality polycrystalline Ba0.7Sr0.3TiO3 (BST0.7) thin films were deposited on fused silica substrates and Si substrates having a thick amorphous SiO2 layer at a relatively low temperature of 550 °C by spin-coating metal organic solutions. The thin films were highly transparent to light in the ultraviolet to near-infrared wavelength regions. The optical propagation loss for a 5-μm-wide and 300-nm-thick polycrystalline waveguide based on BST0.7 was about 17 dB/cm at a wavelength of 632.8 nm. An electro-optic Mach-Zehnder interferometer modulator based on the polycrystalline BST0.7 thin film was monolithically integrated on a Si substrate with standard lithography and wet etching. Optical modulation was successfully demonstrated. The estimated electro-optic coefficient (6.7 pm/V) is the highest reported so far for this kind of film deposited on a fused silica substrate or a Si substrate with an amorphous SiO2 layer.
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42.79.Hp Optical processors, correlators, and modulators
42.79.Gn Optical waveguides and couplers
42.79.Wc Optical coatings
42.70.-a Optical materials
77.55.-g Dielectric thin films
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
07.60.Ly Interferometers
81.65.Cf Surface cleaning, etching, patterning

Linear photon upconversion of 400 meV in an AlGaInP/GaInP quantum well heterostructure to visible light at room temperature

M. R. Olson, K. J. Russell, V. Narayanamurti, J. M. Olson, and Ian Appelbaum

Appl. Phys. Lett. 88, 161108 (2006); http://dx.doi.org/10.1063/1.2195094 (3 pages) | Cited 4 times

Online Publication Date: 17 April 2006

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We linearly up convert photons from 820 to 650 nm, an energy change of ∼ 400 meV, using a AlGaInP/GaInP quantum well heterostructure. Current and luminescence-voltage measurements are presented at temperatures from 6 to 300 K. Photoexcited electrons are injected into the semiconductor from the Au Schottky and a forward bias across the p+-i-n heterostructure drifts electrons into the GaInP quantum well. Holes diffuse from the heavily doped substrate and radiatively recombine, emitting ∼ 650 nm light. Linear upconversion is verified by injecting hot electrons with a solid-state tunnel junction. This device encourages other technologies, including night-vision aids and thermal energy converters.
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78.66.Fd III-V semiconductors
78.67.De Quantum wells
78.55.Cr III-V semiconductors
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Ultrafast carrier dynamics in Au/GaAs interfaces studied by terahertz emission spectroscopy

Yulei Shi, Yuping Yang, Xinlong Xu, Shihua Ma, Wei Yan, and Li Wang

Appl. Phys. Lett. 88, 161109 (2006); http://dx.doi.org/10.1063/1.2196068 (3 pages) | Cited 4 times

Online Publication Date: 18 April 2006

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The measurements of optically generated terahertz emission from Au/GaAs interfaces are investigated in detail. We observe that, under high laser power excitation, terahertz signals from bare GaAs wafers and Au/GaAs samples exhibit an opposite polarity. The polarity-flip behaviors are also observed in temperature-dependent and femtosecond pump-generation studies of the Au/GaAs interfaces.
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78.70.Gq Microwave and radio-frequency interactions
73.40.Ns Metal-nonmetal contacts
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
73.30.+y Surface double layers, Schottky barriers, and work functions
72.40.+w Photoconduction and photovoltaic effects
73.40.Gk Tunneling

Enhanced transmission of optically thick metallic films at infrared wavelengths

Dezhuan Han, Xin Li, Fengqin Wu, Xiaohan Liu, and Jian Zi

Appl. Phys. Lett. 88, 161110 (2006); http://dx.doi.org/10.1063/1.2196467 (3 pages) | Cited 4 times

Online Publication Date: 18 April 2006

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For an optically thick metallic film, the transmission for both s- and p-polarized waves is extremely low. If the metallic film is coated on both sides with a finite dielectric layer, light transmission for p-polarized waves can be enhanced considerably. This enhancement is not related to surface plasmon-polaritions. Instead, it is due to the interplay between Fabry-Perot interference in the coated dielectric layer and the existence of the Brewster angle at the dielectric/metallic interface. It is shown that the coated metallic films can act as excellent polarizers at infrared wavelengths.
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78.66.Bz Metals and metallic alloys
78.30.Er Solid metals and alloys
42.79.Wc Optical coatings
42.79.Ci Filters, zone plates, and polarizers

Nanoscale displacement measurement in a variable-air-gap optical waveguide

Fan Chen, Zhuangqi Cao, Qishun Shen, Xiaoxu Deng, Biming Duan, Wen Yuan, Minghuang Sang, and Shengqian Wang

Appl. Phys. Lett. 88, 161111 (2006); http://dx.doi.org/10.1063/1.2197934 (2 pages) | Cited 1 time

Online Publication Date: 19 April 2006

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Instead of analyzing the fringe shift that was recently developed by us to detect slight displacement, an alternative approach by monitoring changes in the intensity of the light reflected from a variable-air-gap optical waveguide is presented in this work. Owing to the sensitive feature of the ultrahigh-order modes, a 1.7 nm resolution of displacement measurement is demonstrated without any complicated optical interference system and servotechniques.
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06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
42.79.Gn Optical waveguides and couplers

InP-based two-dimensional photonic crystals filled with polymers

R. van der Heijden, C. F. Carlström, J. A. P. Snijders, R. W. van der Heijden, F. Karouta, R. Nötzel, H. W. M. Salemink, B. K. C. Kjellander, C. W. M. Bastiaansen, D. J. Broer, and E. van der Drift

Appl. Phys. Lett. 88, 161112 (2006); http://dx.doi.org/10.1063/1.2196869 (3 pages) | Cited 16 times

Online Publication Date: 19 April 2006

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Polymer filling of the air holes of indium-phosphide-based two-dimensional photonic crystals is reported. After infiltration of the holes with a liquid monomer and solidification of the infill in situ by thermal polymerization, complete filling is proven using scanning electron microscopy. Optical transmission measurements of a filled photonic crystal structure exhibit a redshift of the air band, confirming the complete filling.
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42.70.Qs Photonic bandgap materials
42.70.Jk Polymers and organics
64.70.D- Solid-liquid transitions
82.35.Ej Nonlinear optics with polymers

Resonantly enhanced femtosecond second-harmonic generation and nonlinear luminescence in GaN film grown on sapphire

Hui Yang, S. J. Xu, Q. Li, and Jie Zhang

Appl. Phys. Lett. 88, 161113 (2006); http://dx.doi.org/10.1063/1.2197310 (3 pages) | Cited 7 times

Online Publication Date: 19 April 2006

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At room temperature, by using a tunable broadband femtosecond laser as excitation source we observed second-harmonic generation (SHG) and nonlinear photoluminescence (NPL) in GaN film grown on sapphire simultaneously or individually. In addition to the observation of the resonance effect of the nonlinear response when the SHG is tuned to coincide with the near-band-edge emission, we carefully measured dependence of the SHG and NPL signals on polarization of the excitation light. The results reveal that the reabsorption of the SHG photons with energies higher than the fundamental gap of GaN significantly contributes to generation of the efficient NPL signal.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Light amplification at 501 nm and large nanosecond optical gain in organic dye-doped polymeric waveguides

Grace Jordan, Michael Flämmich, Manuel Rüther, Takeyuki Kobayashi, Werner J. Blau, Yasuhiro Suzuki, and Toshikuni Kaino

Appl. Phys. Lett. 88, 161114 (2006); http://dx.doi.org/10.1063/1.2197314 (3 pages) | Cited 9 times

Online Publication Date: 19 April 2006

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We report on the results of a gain measurement on a substituted stilbene-dye-doped polymer waveguide operating in the blue-green spectral region. By monitoring amplified spontaneous emission from the waveguides under nanosecond photopumping, we deduced net modal gain as large as 84±6 cm−1 at 501 nm, the peak of the gain spectrum, when pumped with a fluence of 1.1 mJ/cm2. Moreover, the effective stimulated emission cross section of 2.7×10−16 cm2 and the loss coefficient of 0.3 cm−1 at 501 nm are extracted. The transparency pump fluence and the corresponding excited state population density are found to be 17 μJ/cm2 and 8.8×1015 cm−3 which is approximately 0.1% of total population, respectively. Comparison is made with other organic and inorganic gain media operating in the short wavelength (violet-green) region of the spectrum. We demonstrate that small-molecule-doped polymers show large gain, comparable with those in conjugated polymers and dendrimers.
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42.55.Mv Dye lasers
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.82.Gw Other integrated-optical elements and systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Efficient laser oscillation of Yb:Y3Al5O12 single crystal grown by temperature gradient technique

Jun Dong, Akira Shirakawa, Ken-ichi Ueda, Jun Xu, and Peizhen Deng

Appl. Phys. Lett. 88, 161115 (2006); http://dx.doi.org/10.1063/1.2197933 (3 pages) | Cited 10 times

Online Publication Date: 20 April 2006

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Low-threshold and highly efficient continuous-wave laser performance of Yb:Y3Al5O12 (Yb:YAG) single crystal grown by a temperature gradient technique (TGT) was achieved at room temperature. The laser can be operated at 1030 and 1049 nm by varying the transmission of the output coupler. Slope efficiencies of 57% and 68% at 1049 and 1030 nm, respectively, were achieved for 10 at. % Yb:YAG sample in continuous-wave laser-diode pumping. The effect of pump power on the laser emission spectrum of both wavelengths is addressed. The near-diffraction-limited beam quality for different laser cavities was achieved. The excellent laser performance indicates that TGT-grown Yb:YAG crystals have very good optical quality and can be potentially used in high-power solid-state lasers.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.70.Hj Laser materials
42.60.By Design of specific laser systems
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Optical distortions through phase transition in the Nd3+:SBN laser crystal

C. Jacinto, D. Jaque, E. Martín Rodríguez, and J. García Solé

Appl. Phys. Lett. 88, 161116 (2006); http://dx.doi.org/10.1063/1.2196473 (3 pages) | Cited 9 times

Online Publication Date: 20 April 2006

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We report on the polarization and temperature dependence of optical distortions of beams passing through a Nd3+-doped Sr0.61Ba0.39Nb2O6 laser crystal. For temperatures close to TC ( ≈ 70 ºC), a strong enhancement in the optical distortion of a nonabsorbed beam takes place, related to the temperature dependence of the r33 electro-optical coefficient during phase transition. From pump and probe experiments, we have concluded that the traditional 808 nm Nd3+ pumping radiation also causes optical distortions, especially for extraordinary polarized radiation.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Coulomb and radiation screening in photoconductive terahertz sources

Dae Sin Kim and D. S. Citrin

Appl. Phys. Lett. 88, 161117 (2006); http://dx.doi.org/10.1063/1.2196480 (3 pages) | Cited 18 times

Online Publication Date: 20 April 2006

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We distinguish the screening contributions due to the Coulomb and radiation parts of the electromagnetic field subsequent to the ultrafast photogeneration of electron-hole pairs in photoconductive GaAs terahertz (THz) sources. We employ the Monte Carlo method self-consistently including the Maxwell equations to study the effects of the excitation-spot size and excitation level on the emitted THz radiation, and find for a range of reasonable excitation levels an excitation-spot diameter of ∼ 100 μm as the crossover point beyond which radiation effects dominate screening.
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07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
84.40.-x Radiowave and microwave (including millimeter wave) technology
42.72.-g Optical sources and standards
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Infrared induced red luminescence of Eu3+-doped polycrystalline LiNbO3

D. Hreniak, W. Strek, A. Speghini, M. Bettinelli, G. Boulon, and Y. Guyot

Appl. Phys. Lett. 88, 161118 (2006); http://dx.doi.org/10.1063/1.2197312 (3 pages) | Cited 13 times

Online Publication Date: 20 April 2006

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Polycrystalline lithium niobate powders were prepared by the sol-gel method. Different grain sizes were obtained by controlling the annealing temperature. The Eu3+ ion was used as a luminescent probe of the nonlinear optical properties of the grains. Strong red emission deriving from Eu3+ ions was observed under pulsed infrared laser irradiation at 936.0 nm due to absorption of the light produced in the second harmonic generation process. A measurable emission was observed only for grains having a size of the least 200 nm, depending on the annealing temperature.
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42.70.-a Optical materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.55.Hx Other solid inorganic materials
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
81.40.Gh Other heat and thermomechanical treatments

Loss management using parity-selective barriers for single-mode, single-cell photonic crystal resonators

Sun-Kyung Kim, Guk-Hyun Kim, Se-Heon Kim, Yong-Hee Lee, Sung-Bock Kim, and In Kim

Appl. Phys. Lett. 88, 161119 (2006); http://dx.doi.org/10.1063/1.2193651 (3 pages) | Cited 7 times

Online Publication Date: 21 April 2006

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We propose and realize truly single-mode, single-cell photonic crystal resonators surrounded by six symmetric waveguides. The waveguides provide different parity-selective loss paths for different resonant cavity modes. We found symmetry conditions where only the hexapole mode is well confined while the other modes are severely leaky along the waveguides. Utilizing the parameters derived from this parity-mismatch principle, the hexapole-mode resonators were fabricated on InP–InGaAsP slabs. Through photopumping, we obtained the hexapole-mode laser operating in a single mode over a wide range of around 100 nm.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.82.Gw Other integrated-optical elements and systems

Second-harmonic generation from Si/SiO2/Hf(1−x)SixO2 structures

R. Carriles, J. Kwon, Y. Q. An, J. C. Miller, M. C. Downer, J. Price, and A. C. Diebold

Appl. Phys. Lett. 88, 161120 (2006); http://dx.doi.org/10.1063/1.2197935 (3 pages) | Cited 8 times

Online Publication Date: 21 April 2006

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Optical second-harmonic generation (SHG) is used to characterize thin films of Hf(1−x)SixO2 (x = 0, 0.3, 0.45, 0.65, and 1) deposited by atomic layer epitaxy at 375 °C on Si substrates with 11 Å SiO2 buffer layers. Reflected SHG intensity measured at room temperature increases monotonically with Hf content for as-deposited samples and varies strongly with the temperature (600–1000 °C) of postdeposition rapid anneals in NH3. Spectroscopic analysis shows that the variable SHG component peaks at SH photon energy of 3.37 eV—the bulk silicon E1 critical point energy—a clear signature of electric-field-induced second-harmonic generation in the bulk Si space-charge region. The results suggest that SHG is a sensitive, potentially in situ, probe of internal electric fields attributable to composition- and annealing-dependent fixed charge in the oxide layers.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.66.-w Optical properties of specific thin films
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.79.Wc Optical coatings
78.20.Jq Electro-optical effects
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Effect of Auger recombination on the performance of p-doped quantum dot lasers

S. Mokkapati, M. Buda, H. H. Tan, and C. Jagadish

Appl. Phys. Lett. 88, 161121 (2006); http://dx.doi.org/10.1063/1.2193433 (3 pages) | Cited 8 times

Online Publication Date: 21 April 2006

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Experimental results on spontaneous emission rates from InGaAs quantum dot lasers that can be explained theoretically by considering the influence of nonradiative mixed state recombinations in the quantum dot-wetting layer system are presented. Our model qualitatively explains the experimental results such as an increase in the threshold current density, temperature stability, and a narrower gain spectrum due to doping the quantum dot active region with the acceptors. Our model also predicts that moderate acceptor concentrations can improve the laser performance at higher carrier injection densities; but high acceptor concentrations deteriorate the laser performance due to the nonradiative Auger recombination that counteracts the benefits of increased spontaneous emission rates.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Isotropic left handed material at optical frequency with dielectric spheres embedded in negative permittivity medium

Byoung-Joon Seo, Tetsuya Ueda, Tatsuo Itoh, and Harold Fetterman

Appl. Phys. Lett. 88, 161122 (2006); http://dx.doi.org/10.1063/1.2196871 (3 pages) | Cited 15 times

Online Publication Date: 21 April 2006

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A possibility to realize an isotropic left handed material up to optical frequencies is theoretically investigated. The proposed homogeneous structure consists of dielectric spheres embedded randomly in a negative permittivity host medium. While the effective permittivity of the structure is negative over a wide frequency range due to the host medium, the negative effective permeability is obtained by spherical magnetic resonances of the dielectric spheres. Since this structure utilizes only magnetic resonance, both analytical and numerical simulation results show that it has higher fabrication tolerance, larger bandwidth and potentially less propagation loss than the previously proposed structure, i.e., the dielectric spheres embedded in the dielectric host.
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42.70.-a Optical materials
77.22.Ch Permittivity (dielectric function)
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Low-density tin targets for efficient extreme ultraviolet light emission from laser-produced plasmas

Tomoharu Okuno, Shinsuke Fujioka, Hiroaki Nishimura, Yezheng Tao, Keiji Nagai, Qincui Gu, Nobuyoshi Ueda, Tsuyoshi Ando, Katsunobu Nishihara, Takayoshi Norimatsu, Noriaki Miyanaga, Yasukazu Izawa, Kunioki Mima, Atsushi Sunahara, Hiroyuki Furukawa, et al.

Appl. Phys. Lett. 88, 161501 (2006); http://dx.doi.org/10.1063/1.2195693 (3 pages) | Cited 23 times

Online Publication Date: 18 April 2006

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Influence of initial density of tin (Sn) targets has been quantitatively investigated for efficient extreme ultraviolet light emission from laser-produced plasmas. With a decrease in the initial density, conversion efficiency (CE) from incident laser energy to output 13.5 nm light energy in a 2% bandwidth increases; 2.2% of the peak CE was attained with use of 7% low-density SnO2 targets (0.49 g/cm3) irradiated with a Nd:YAG laser, of which wavelength, pulse duration, and intensity are, respectively, 1.064 μm, 10 ns, and 5×1010 W/cm2. The peak CE is 1.7 times higher than that obtained with the use of solid density Sn targets. Experimental results may be attributed to the influence of the initial density and/or microstructure of the targets on expansion dynamics of the plasmas.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.70.La X-ray and γ-ray measurements
52.30.-q Plasma dynamics and flow

Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses

Takeshi Higashiguchi, Keita Kawasaki, Wataru Sasaki, and Shoichi Kubodera

Appl. Phys. Lett. 88, 161502 (2006); http://dx.doi.org/10.1063/1.2195904 (3 pages) | Cited 18 times

Online Publication Date: 20 April 2006

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We demonstrated enhancement of extreme ultraviolet (EUV) emission at 13.5 nm from a lithium plasma by use of dual laser pulses. A single laser pulse produced a lithium plasma condition for the EUV emission far beyond its optimum. Utilization of dual laser pulses, however, enhanced the EUV emission energy, and its maximum in-band EUV conversion efficiency (CE) in a measured solid angle was observed to be 2.4% at a pulse separation time between 20 and 50 ns. The EUV CE became 1.8 times as large as that produced by a single laser pulse, which was one of the highest values ever reported. Enhancement of the EUV CE was attributed to the decrease of the plasma temperature and density to their optimum values.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.70.La X-ray and γ-ray measurements

Effective plasma confinement by applying multipolar magnetic fields in an internal linear inductively coupled plasma system

Kyong Nam Kim, Mi Suk Kim, and Geun Young Yeom

Appl. Phys. Lett. 88, 161503 (2006); http://dx.doi.org/10.1063/1.2188037 (3 pages) | Cited 7 times

Online Publication Date: 21 April 2006

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Show Abstract
A novel internal-type linear inductive antenna referred to as “double comb-type antenna” was used for a large-area plasma source with the substrate area of 880 mm×660 mm and the effect of plasma confinement by applying multi-polar magnetic field was investigated. High-density plasmas on the order of 3.18×1011 cm−3, which is 50% higher than that obtained for the source without the magnetic field, could be obtained at the pressure of 15 mTorr Ar and at the inductive power of 5000 W with good plasma stability. The plasma uniformity less than 3% could also be obtained within the substrate area. When SiO2 film was etched using the double comb-type antenna, the average etch rate of about 2100 Å/min could be obtained with the etch uniformity of 5.4% on the substrate area using 15 mTorr SF6, 5000 W of rf power, and −34 V of dc bias voltage.
Show PACS
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium
52.50.Dg Plasma sources
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.77.Bn Etching and cleaning
52.40.Hf Plasma-material interactions; boundary layer effects
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