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17 Mar 2003

Volume 82, Issue 11, pp. 1649-1799

Issue Cover Spotlight Figure

Appl. Phys. Lett. 82, 1709 (2003); http://dx.doi.org/10.1063/1.1560575 (3 pages)

Ji-Won Oh, Masahiro Yoshita, Hidefumi Akiyama, Loren N. Pfeiffer, and Ken W. West
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Void channel microstructures in resin solids as an efficient way to infrared photonic crystals

M. J. Ventura, M. Straub, and M. Gu

Appl. Phys. Lett. 82, 1649 (2003); http://dx.doi.org/10.1063/1.1560870 (3 pages) | Cited 32 times

Online Publication Date: 10 March 2003

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Microvoid channels were generated by local melting in a solidified polymer resin sample moving perpendicular to the focus of a high numerical-aperture objective under visible femtosecond-pulsed illumination. Channel size, surface quality, and high density channel vicinity depended on laser intensity and scanning speed. Electron microscope images revealed elliptical channel cross sections of 0.7–1.3 μm in lateral diameter and an elongation in the focusing direction of approximately 50%. A 20 layer woodpile-type photonic crystal structure with a 1.7 μm layer spacing and a 1.8 μm in-plane channel spacing provided a sharp peak in reflection and a suppression of infrared transmission in the stacking direction by 85% at wavelength 4.8 μm with a gap/midgap ratio of 0.11. © 2003 American Institute of Physics.
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42.55.Tv Photonic crystal lasers and coherent effects
42.70.Qs Photonic bandgap materials
42.86.+b Optical workshop techniques
42.62.-b Laser applications
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.47.-p Spectroscopy of solid state dynamics

Temporally multiplexed holographic polymer-dispersed liquid crystals

J. Qi, M. E. Sousa, A. K. Fontecchio, and G. P. Crawford

Appl. Phys. Lett. 82, 1652 (2003); http://dx.doi.org/10.1063/1.1557767 (3 pages) | Cited 18 times

Online Publication Date: 10 March 2003

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We report on a temporal multiplexing technique to fabricate multiple reflection gratings in holographic polymer-dispersed liquid crystals. By time-sequentially exposing the sample, two switchable reflection gratings are formed in a single film. The reflectance of the resulting gratings is well controlled by the individual exposure time. The observed transmission spectra are in excellent agreement with our model based on the reaction-diffusion equation to predict the kinetics of formation and the 2×2 matrix method to model the optical performance. © 2003 American Institute of Physics.
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42.40.Eq Holographic optical elements; holographic gratings
42.70.Df Liquid crystals
61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems

Spectral and time-resolved photoluminescence studies of Eu-doped GaN

Ei Ei Nyein, U. Hömmerich, J. Heikenfeld, D. S. Lee, A. J. Steckl, and J. M. Zavada

Appl. Phys. Lett. 82, 1655 (2003); http://dx.doi.org/10.1063/1.1560557 (3 pages) | Cited 75 times

Online Publication Date: 10 March 2003

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We report on spectral and time-resolved photoluminescence (PL) studies performed on Eu-doped GaN prepared by solid-source molecular-beam epitaxy. Using above-gap excitation, the integrated PL intensity of the main Eu3+ line at 622.3 nm (5D0→7F2 transition) decreased by nearly 90% between 14 K and room temperature. Using below-gap excitation, the integrated intensity of this line decreased by only ∼ 50% for the same temperature range. In addition, the Eu3+ PL spectrum and decay dynamics changed significantly compared to above-gap excitation. These results suggest the existence of different Eu3+ centers with distinct optical properties. Photoluminescence excitation measurements revealed resonant intra-4f absorption lines of Eu3+ ions, as well as a broad excitation band centered at ∼ 400 nm. This broad excitation band overlaps higher lying intra-4f Eu3+ energy levels, providing an efficient pathway for carrier-mediated excitation of Eu3+ ions in GaN. © 2003 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.47.-p Spectroscopy of solid state dynamics

Growth of room-temperature “arsenic free” infrared photovoltaic detectors on GaSb substrate using metamorphic InAlSb digital alloy buffer layers

E. Plis, P. Rotella, S. Raghavan, L. R. Dawson, S. Krishna, D. Le, and C. P. Morath

Appl. Phys. Lett. 82, 1658 (2003); http://dx.doi.org/10.1063/1.1556167 (3 pages) | Cited 2 times

Online Publication Date: 10 March 2003

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We report the growth of a high-quality graded InAlSb digital alloy buffer layer on GaSb substrates. The metamorphic buffer layer relaxes the lattice matching constraint and allows the growth of heterostructures without the use of a second group V element. Cross-sectional transmission electronic microscopy images reveal a very low dislocation density in the buffer layer. Using such a buffer layer, a room-temperature InGaSb photovoltaic detector with λcutoff ∼ 3 μm has been fabricated with an external quantum efficiency >70%. © 2003 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
68.65.Cd Superlattices
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Lp Transmission electron microscopy (TEM)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
61.72.Lk Linear defects: dislocations, disclinations

Theoretical investigation of a two-dimensional photonic crystal slab with truncated cone air holes

Yoshinori Tanaka, Takashi Asano, Yoshihiro Akahane, Bong-Shik Song, and Susumu Noda

Appl. Phys. Lett. 82, 1661 (2003); http://dx.doi.org/10.1063/1.1559947 (3 pages) | Cited 66 times

Online Publication Date: 10 March 2003

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The effects of truncated cone air holes on propagation losses from line defect waveguides in two-dimensional (2D) photonic crystal (PC) slabs are investigated. It is shown that coupling between TE-like waveguide modes and TM-like slab modes due to out-of-plane structural asymmetries can result in large propagation losses. It is also shown that coupling, and therefore propagation loss, does not occur in a frequency range where wave vectors of TE-like waveguide modes do not match projections of those of TM-like slab modes. The results are thought to be applicable to other structures exhibiting out-of-plane asymmetries, such as 2D PC slabs attached to silicon on insulator substrates. © 2003 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays

Interferometric study of thermal dynamics in GaAs-based quantum-cascade lasers

C. Pflügl, M. Litzenberger, W. Schrenk, D. Pogany, E. Gornik, and G. Strasser

Appl. Phys. Lett. 82, 1664 (2003); http://dx.doi.org/10.1063/1.1561582 (3 pages) | Cited 26 times

Online Publication Date: 10 March 2003

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The thermal dynamics in quantum-cascade lasers under pulsed operation is investigated by a scanning interferometric thermal mapping technique. An infrared laser beam probes the change in the refractive index caused by current-induced heating of the working devices. The measured phase shift provides a quantitative information on the thermal characteristics with a micrometer spatial and a nanosecond time resolution. Comparing the experiments with a two-dimensional thermal model enables us to determine the anisotropic heat conductivity in the multilayered active region, found to be much lower than the one of bulk GaAs, as well as the temperature increase in the active region during pulsed operation. © 2003 American Institute of Physics.
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66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
78.66.Fd III-V semiconductors

Fabrication of three-dimensional polymer photonic crystal structures using single diffraction element interference lithography

Ivan Divliansky, Theresa S. Mayer, Kito S. Holliday, and Vincent H. Crespi

Appl. Phys. Lett. 82, 1667 (2003); http://dx.doi.org/10.1063/1.1560860 (3 pages) | Cited 53 times

Online Publication Date: 10 March 2003

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This letter describes an approach for recording three-dimensional (3D) periodic structures in a photosensitive polymer using a single diffraction element mask. The mask has a central opening surrounded by three diffraction gratings oriented 120° relative to one another such that the three first order diffracted beams and the nondiffracted laser beam give a 3D spatial light intensity pattern. Structures patterned in this polymer using 1.0 and 0.56 μm grating periods have hexagonal symmetry with micron- to submicron-periodicity over large substrate area. Band structure calculations of these low index contrast materials predict photonic gaps in certain high symmetry directions. © 2003 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.70.Jk Polymers and organics
42.79.Dj Gratings
42.86.+b Optical workshop techniques

Ultrashort, nonlinear, optical time response of Fe-doped InGaAs/InP multiple quantum wells in 1.55-μm range

M. Guézo, S. Loualiche, J. Even, A. Le Corre, H. Folliot, C. Labbé, O. Dehaese, and G. Dousselin

Appl. Phys. Lett. 82, 1670 (2003); http://dx.doi.org/10.1063/1.1557333 (3 pages) | Cited 7 times

Online Publication Date: 10 March 2003

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Pump-probe experiments are used to characterize Fe-doped InGaAs/InP multiple quantum wells for ultrafast saturable absorption applications. Sample photoresponse time is well controlled by iron doping from the nanosecond range to a value as short as 0.45 ps for an iron concentration of 6×1018 cm−3. Furthermore, the switching amplitude, that is, the differential transmission ratio (DTR), of samples having increasing Fe doping (null to 6×1018 cm−3) presents two decreasing regimes at moderate optical excitation levels. The first one is explained well by the degree of quality of the material, whereas the second one is interpreted as an inhibition of exciton formation at high doping levels. This interpretation is highlighted by an analysis of the temporal evolution of the DTR. The influence of the doping localization (in the well, in the barrier, or in the whole structure) is studied as well. Finally, an attractive way to maintain a constant value of the DTR with an ultrafast response time (2.6 ps) is proposed and demonstrated. © 2003 American Institute of Physics.
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78.67.De Quantum wells
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
42.65.Pc Optical bistability, multistability, and switching, including local field effects
78.47.-p Spectroscopy of solid state dynamics
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
78.30.Fs III-V and II-VI semiconductors

Parametric study of Ga1−xInxNyAs1−y/GaAs quantum wells for 1.3-μm laser operation

W. W. Chow and J. S. Harris

Appl. Phys. Lett. 82, 1673 (2003); http://dx.doi.org/10.1063/1.1561154 (3 pages) | Cited 7 times

Online Publication Date: 10 March 2003

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A microscopic laser theory was used to investigate gain properties in Ga1−xInxNyAs1−y/GaAs quantum wells. We considered combinations of x and y giving laser emission around 1.30 μm. Optical properties affecting laser threshold and dynamical response are described for structures with strain ranging from compressive to tensile. A parametric study of this kind should provide useful information for the optimization of GaInNAs vertical-cavity surface-emitting laser gain media for telecommunications applications. © 2003 American Institute of Physics.
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42.70.Hj Laser materials
78.67.De Quantum wells
78.55.Cr III-V semiconductors
68.65.Fg Quantum wells

Near-field scanning optical microscopy of photonic crystal nanocavities

Koichi Okamoto, Marko Lončar, Tomoyuki Yoshie, Axel Scherer, Yueming Qiu, and Pawan Gogna

Appl. Phys. Lett. 82, 1676 (2003); http://dx.doi.org/10.1063/1.1559646 (3 pages) | Cited 24 times

Online Publication Date: 10 March 2003

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Near-field scanning optical microscopy was used to observe high-resolution images of confined modes and photonic bands of planar photonic crystal (PPC) nanocavities fabricated in active InGaAsP material. We have observed the smallest optical cavity modes, which are intentionally produced by fractional edge dislocation high-Q cavity designs. The size of the detected mode was roughly four by three lattice spacings. We have also observed extended dielectric-band modes of the bulk PPC surrounding the nanocavity by geometrically altering the bands in emission range and eliminating localized modes out of the emission range. © 2003 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.55.Tv Photonic crystal lasers and coherent effects
68.65.Fg Quantum wells
68.37.Uv Near-field scanning microscopy and spectroscopy
42.55.Sa Microcavity and microdisk lasers
78.67.De Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
63.20.Pw Localized modes
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.55.Cr III-V semiconductors
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