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15 Sep 2006

Volume 100, Issue 6, Articles (06xxxx)

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Resonant photonic band gap structures realized from molecular-beam-epitaxially grown InGaAs/GaAs Bragg-spaced quantum wells

J. P. Prineas, C. Cao, M. Yildirim, W. Johnston, and M. Reddy

J. Appl. Phys. 100, 063101 (2006); http://dx.doi.org/10.1063/1.2234814 (14 pages) | Cited 9 times

Online Publication Date: 21 September 2006

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We present a comprehensive study of the growth and fabrication of Bragg-spaced quantum wells, a type of resonant photonic band gap structure. To begin, we considered the impact of disorder and drift in the periodicity of the quantum wells on the formation of the resonant photonic band gap. We found that steady decrease in the periodicity greater than a few percent leads to collapse of the resonant photonic band gap, while random disorder in the quantum well periodicity of several percent leads to extra peaks in the resonant photonic band gap due to coupling to “intermediate band” states. Next, we optimized the growth of low x (x ⩽ 0.06) InxGa1−xAs/GaAs quantum wells, the building block of Bragg-spaced quantum well structures. Growth parameters optimized include growth rate, modulation of substrate temperature for barrier/quantum well, and V/III flux ratio. Fast growth of quantum wells was achieved with some of the narrowest heavy-hole exciton linewidths (0.37 meV) reported to date for quantum wells of these widths. Using the optimized InGaAs/GaAs quantum wells as a building block, we grew near-ideal N = 210 Bragg-spaced quantum well structures. By monitoring growth rates during growth with reflection high energy electron diffraction and correcting drift by adjusting cell temperature, drift and disorder in periodicity were kept to less than 1%. We see no fundamental barriers to growing much longer structures such as N = 1000 periods or longer.
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81.07.St Quantum wells
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.67.De Quantum wells
68.65.Fg Quantum wells
73.21.Fg Quantum wells
71.35.-y Excitons and related phenomena

Influence of laser intensity on absorption line broadening in laser absorption spectroscopy

Makoto Matsui, Kimiya Komurasaki, Satoshi Ogawa, and Yoshihiro Arakawa

J. Appl. Phys. 100, 063102 (2006); http://dx.doi.org/10.1063/1.2353893 (4 pages) | Cited 4 times

Online Publication Date: 22 September 2006

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The influence of laser intensity on absorption line broadening was investigated. Laser absorption spectroscopy was applied to low-pressure plasma, and the translational temperature deduced from the Doppler width was found to increase with laser intensity; this was in contrast to the conventional laser theory. Consequently, the dependency of absorption saturation on the Doppler frequency was considered. The predicted variation in broadening width with laser intensity showed a good agreement with the measurement. In addition, we obtained a correction factor for the temperature measurement at high laser intensity.
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52.25.Tx Emission, absorption, and scattering of particles
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
42.62.Fi Laser spectroscopy
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy

Enhancement of second harmonic generation signal in thermally poled glass ceramic with NaNbO3 nanocrystals

Artem Malakho, Evelyne Fargin, Michel Lahaye, Bogdan Lazoryak, Vladimir Morozov, Gustaaf Van Tendeloo, Vincent Rodriguez, and Frederic Adamietz

J. Appl. Phys. 100, 063103 (2006); http://dx.doi.org/10.1063/1.2259816 (5 pages) | Cited 9 times

Online Publication Date: 22 September 2006

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Glass ceramic composites were prepared by bulk crystallization of NaNbO3 in sodium niobium borate glasses. A homogeneous bulk crystallization of the NaNbO3 phase takes place during heat treatments that produces visible-near infrared transparent materials with ∼ 30 nm NaNbO3 nanocrystallites. Upon thermal poling, a strong Na+ depleted nonlinear optical thin layer is observed at the anode side that should induce a large internal static electric field. In addition, the χ(2) response of the poled glass ceramic composites increases from 0.2 up to 1.9 pm/V with the rate of crystallization. Two mechanisms may be considered: a pure structural χ(2) process connected with the occurrence of a spontaneous ferroelectric polarization or an increase of the χ(3) response of the nanocrystallites that enhances the electric field induced second harmonic generation process.
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81.05.Pj Glass-based composites, vitroceramics
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Ce Glasses, quartz
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
77.22.Ej Polarization and depolarization
77.80.-e Ferroelectricity and antiferroelectricity

Holographic capture of femtosecond pulse propagation

Martin Centurion, Ye Pu, and Demetri Psaltis

J. Appl. Phys. 100, 063104 (2006); http://dx.doi.org/10.1063/1.2345469 (9 pages) | Cited 15 times

Online Publication Date: 22 September 2006

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We have implemented a holographic system to study the propagation of femtosecond laser pulses with high temporal (150 fs) and spatial resolutions (4 μm). The phase information in the holograms allows us to reconstruct both positive and negative index changes due to the Kerr nonlinearity (positive) and plasma formation (negative), and to reconstruct three-dimensional structure. Dramatic differences were observed in the interaction of focused femtosecond pulses with air, water, and carbon disulfide. The air becomes ionized in the focal region, while in water long plasma filaments appear before the light reaches a tight focus. In contrast, in carbon disulfide the optical beam breaks up into multiple filaments but no plasma is measured. We explain these different propagation regimes in terms of the different nonlinear material properties.
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42.40.Ht Hologram recording and readout methods
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.38.-r Laser-plasma interactions
42.30.Wb Image reconstruction; tomography

Near-field imaging in the megahertz range by strongly coupled magnetoinductive surfaces: Experiment and ab initio analysis

Manuel J. Freire and Ricardo Marques

J. Appl. Phys. 100, 063105 (2006); http://dx.doi.org/10.1063/1.2349469 (9 pages) | Cited 16 times

Online Publication Date: 25 September 2006

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In this work, the previously reported near-field imaging by two strongly coupled arrays of planar magnetic resonators is further studied. Experiments are performed to clarify the physical mechanisms underlying such an effect. The specific aim of these experiments is to clarify both the role played by magnetoinductive surface waves (MISWs) and the presence in the device of evanescent Fourier harmonics amplification. In addition to the experimental work, an ab initio theoretical analysis is developed to obtain a first approximation of the above effects. This model assumes that MISWs play the same role as plasmon-polaritons in negative refractive slabs, thus producing amplification of evanescent Fourier harmonics in the device. It also predicts that imaging occurs close to the resonators’ resonant frequency, between the passbands for the two MISW branches that can be excited in the lens. Both predictions from the theoretical model are in qualitative agreement with the experimental results. Quantitative agreement can also be obtained if some appropriate additional hypotheses, taking into account the discrete nature of the present device, are included in the model. The reported results suggest the possibility of using this kind of device for imaging in the megahertz range such as in nuclear magnetic resonance imaging.
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85.70.Sq Magnetooptical devices
42.79.Bh Lenses, prisms and mirrors

Polarization-dependent optical characterization of poly(phenylquinoxaline) thin films

V. Ksianzou, R. K. Velagapudi, B. Grimm, and S. Schrader

J. Appl. Phys. 100, 063106 (2006); http://dx.doi.org/10.1063/1.2349471 (8 pages) | Cited 5 times

Online Publication Date: 25 September 2006

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Linear optical properties of two types of poly(phenylquinoxaline) (PPQ) are studied by multiwavelength prism coupling technique and optical absorption spectroscopy. Surface roughness measurements are done using atomic force microscopy. PPQs form smooth films of high optical quality having refractive indices above 1.7 in the visible and near infrared spectral ranges. Enhanced birefringence of Δn ∼ 0.04 has been observed in both PPQ films prepared by spin coating. Sellmeier coefficients are derived for the wavelength range starting from 0.532 to 1.064 μm for both TE and TM polarizations. Quantum chemical calculations both on the semiempirical and on the ab initio level are carried out in order to calculate the first-order molecular polarizability tensors of the polymer repeat units. From the obtained tensor elements, theoretical values for both the average refractive indices and the maximum expectable birefringence are calculated. Based on these values a more detailed interpretation of the experimental findings is carried out. The dispersion of refractive index is quantified by the value of Abbe’s constant (νd). In our case the value νd ≈ 11 indicates high dispersion in the visible spectral range. The imaginary part k of the complex refractive index n* = n−ik reaches values of k ⩽ 10−3 in the wavelength range from 0.5 to 1 μm.
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78.66.Qn Polymers; organic compounds
42.70.Jk Polymers and organics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.20.Fm Birefringence
68.37.Ps Atomic force microscopy (AFM)
68.47.Mn Polymer surfaces

Improved optical properties of InAs quantum dots grown with an As2 source using molecular beam epitaxy

Takeyoshi Sugaya, Takeru Amano, and Kazuhiro Komori

J. Appl. Phys. 100, 063107 (2006); http://dx.doi.org/10.1063/1.2352809 (4 pages) | Cited 19 times

Online Publication Date: 26 September 2006

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We demonstrate the effects of using an As2 source to fabricate self-organized InAs/GaAs quantum dot (QD) structures. QDs grown with an As2 source have narrower photoluminescence (PL) linewidths and higher PL intensities than those grown with an As4 source at high growth rates. The density of QDs grown with an As2 source is smaller, and the dot size larger than those of QDs grown with an As4 source. The coalescence of QDs is reduced under an As2 source, resulting in improved optical properties. These results are thought to result from the difference in the surface migration of In atoms and the surface structures under As2 and As4 sources.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
81.07.Ta Quantum dots
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Polarization of gain and symmetry breaking by interband coupling in quantum well lasers

Fredrik Boxberg, Roman Tereshonkov, and Jukka Tulkki

J. Appl. Phys. 100, 063108 (2006); http://dx.doi.org/10.1063/1.2353276 (10 pages) | Cited 2 times

Online Publication Date: 26 September 2006

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We have studied the influence of conduction band–valence band coupling on the polarization of gain in quantum well (QW) lasers. As a reference we used the eight-band k∙p description of the gain polarization. Our eight-band k∙p model accounts for the crystal orientation, lack of inversion symmetry, strain induced deformation potentials, and piezoelectricity. We have studied both strained and unstrained (001) and (111) QWs. The results are compared with the transition dipole model of the gain polarization [ M. Asada et al., IEEE J. Quantum Electron. 20, 745 (1984) ], which is based on a phenomenological generalization of Kane’s [J. Phys. Chem. Solids 1, 249 (1957) ] linear k∙p model of bulk crystals. We found a quantitative difference between our multiband model and the transition dipole model of Asada et al. The difference is addressed to lack of orthogonality between the transition dipole and the electron wave vectors. The orthogonality is broken outside the Γ point by both the QW heterostructure geometry and the interband coupling. Results obtained by the complete eight-band model are also compared with restricted multiband models excluding the conduction band.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Space qualification and environmental testing of quasicontinuous wave laser diode arrays

Elisavet Troupaki, Aleksey A. Vasilyev, Nasir B. Kashem, Graham R. Allan, and Mark A. Stephen

J. Appl. Phys. 100, 063109 (2006); http://dx.doi.org/10.1063/1.2353795 (5 pages) | Cited 4 times

Online Publication Date: 27 September 2006

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NASA’s mission requirements for spaceborne laser diode arrays lead to a set of tests peculiar to space flight. The goal of these tests is to determine if vibration, radiation, or vacuum will impair the operation or lifetime of nominally 100 W quasicontinuous wave 808 nm laser diode arrays. To simulate the stresses expected during a mission, terrestrial tests involve mechanical vibration, simulating the acceleration of launch, exposure to the equivalent doses of ionizing radiation, and operation in a vacuum. Three sets of devices were tested: one set with random vibration up to 20 g root-mean-square (grms) applied along three axes, a second set of devices was irradiated with γ radiation (1.17 and 1.33 MeV) at 744 rad(Si)∕min up to 200 krad(Si), and the third set was exposed to a flux of 5×1011 or 1012 p/cm2 of 200 MeV protons up to 60 krad total dose. Only the proton irradiated devices showed any effect attributable to the test: a slight rise in lasing threshold, which recovered over time with self-annealing. A selection of the devices were then operated in vacuum for a further 1400 h accumulating 500×106 pulses without any signs of degradation. Similar results were obtained in a parallel test, conducted in air, accumulating over 109 pulses on a selection of the remaining devices.
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42.55.Px Semiconductor lasers; laser diodes
42.62.-b Laser applications
95.55.Pe Lunar, planetary, and deep-space probes
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