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12 Mar 2001

Volume 78, Issue 11, pp. 1463-1639

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Near-field photocurrent imaging of the optical mode profiles of semiconductor laser diodes

T. Guenther, V. Malyarchuk, J. W. Tomm, R. Müller, C. Lienau, and J. Luft

Appl. Phys. Lett. 78, 1463 (2001); http://dx.doi.org/10.1063/1.1342206 (3 pages) | Cited 4 times

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The potential of near-field photocurrent spectroscopy for direct imaging of mode profiles of submicron-sized waveguides in optoelectronic devices is demonstrated. The technique combines the submicron spatial resolution of near-field optics with tunable laser excitation, allowing for selective investigation of the waveguide properties of the device structure. Experiments on InGaAs/AlGaAs high-power laser diodes with different waveguide designs provide direct visualization of the effect of the waveguide design on (i) the number of guided modes and (ii) the spatial profile of both fundamental and higher-order modes. The technique thus provides a sensitive tool for nondestructive in situ analysis of waveguide properties in optoelectronic devices. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.82.Bq Design and performance testing of integrated-optical systems
07.79.Fc Near-field scanning optical microscopes

Photonic crystal waveguides: Out-of-plane losses and adiabatic modal conversion

M. Palamaru and Ph. Lalanne

Appl. Phys. Lett. 78, 1466 (2001); http://dx.doi.org/10.1063/1.1354666 (3 pages) | Cited 67 times

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An accurate model for the out-of-plane radiation losses occurring when a guided wave propagating in a conventional waveguide impinges on a photonic crystal waveguide is presented. The model makes clear that the losses originate from insertion losses resulting from a mode mismatch. A generic taper structure realizing an adiabatic modal conversion is proposed and validated through numerical computations for cavities with large Q’s and large peak transmission. © 2001 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.50.-p Quantum optics
42.70.Qs Photonic bandgap materials
42.82.Et Waveguides, couplers, and arrays

Stimulated emission and optical gain in ZnO epilayers grown by plasma-assisted molecular-beam epitaxy with buffers

Yefan Chen, N. T. Tuan, Yusaburo Segawa, Hang-ju Ko, Soon-ku Hong, and Takafumi Yao

Appl. Phys. Lett. 78, 1469 (2001); http://dx.doi.org/10.1063/1.1355665 (3 pages) | Cited 85 times

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We report the results of an experimental investigation on lasing mechanisms in optically pumped ZnO epilayers at room temperature. High-quality ZnO epilayers grown on sapphire by plasma-assisted molecular-beam epitaxy employing an MgO buffer were used. Free exciton emissions and their phonon replicas dominate the photoluminescence from low excited samples. Inelastic exciton–exciton scattering contributes to the mechanism of stimulated emission mainly at intermediate excitation. By using the variable stripe length method, we measured the near threshold optical gain spectrum of the ZnO epilayers. Different from the interband transition governed mechanisms, exciton–exciton scattering gives rise to a nearly symmetric gain spectrum with the peak at 3.17 eV. The electron-hole plasma emerges to contribute to the optical gain when excitation exceeds 220 kW/cm2. © 2001 American Institute of Physics.
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78.45.+h Stimulated emission
78.66.Hf II-VI semiconductors
42.55.Px Semiconductor lasers; laser diodes
78.55.Et II-VI semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
63.20.kk Phonon interactions with other quasiparticles

Birefringence evaluation of multimode multilayer AlGaAs/AlAs waveguides

G. Leo, M. Secondini, M. Morabito, A. De Rossi, G. Assanto, A. Fiore, V. Berger, M. Calligaro, and J. Nagle

Appl. Phys. Lett. 78, 1472 (2001); http://dx.doi.org/10.1063/1.1355005 (3 pages) | Cited 4 times

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We investigate surface-emitting second harmonic generation as a powerful technique for the evaluation of birefringence in optical waveguides supporting several modes. This one-shot diagnostic is demonstrated at 1319 nm in multilayer AlGaAs waveguides, before and after the lateral oxidation of AlAs layers. © 2001 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
78.20.Fm Birefringence
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Wi Nonlinear waveguides
42.79.Wc Optical coatings
78.66.Fd III-V semiconductors

Photonic-crystal distributed-feedback lasers

I. Vurgaftman and J. R. Meyer

Appl. Phys. Lett. 78, 1475 (2001); http://dx.doi.org/10.1063/1.1355670 (3 pages) | Cited 17 times

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The far-field emission characteristics and spectral purity of photonic-crystal distributed-feedback (PCDFB) lasers, in which the grating is defined on a two-dimensional lattice that is tilted with respect to the facets, are analyzed using a self-consistent time-domain simulation. It is shown that both conventional DFB and angled-grating DFB devices are special cases of the PCDFB laser, which combines and enhances the best features of each. The simulations project both high beam quality and high spectral purity out to pump stripes of width ≫100 μm. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.70.Qs Photonic bandgap materials

Morphology and photonic band structure modification of polystyrene particle layers by reactive ion etching

Toru Fujimura, Tsuyoshi Tamura, Tadashi Itoh, Chiseki Haginoya, Yuri Komori, and Takao Koda

Appl. Phys. Lett. 78, 1478 (2001); http://dx.doi.org/10.1063/1.1353844 (3 pages) | Cited 15 times

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Morphology of self-assembled polystyrene particle layers has been modified by reactive ion etching. The etched layers have two-dimensional periodic structures in submicron scale, the period of which is determined by the initial size of the particles, and the shape of the etched particles has been gradually changed to a thinner ellipsoid depending on the etching time. Resonant phenomenon between incident light and electromagnetic eigenmodes of the photonic band of the etched layers has been observed in transmission measurement. The resonant frequencies have gradually shifted according to the etching time, i.e., the photonic band structure of the layers has been successfully modified. Various kinds of applications can be expected due to the electromagnetic resonant phenomenon and the characteristic surface structure of the layers. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
81.65.Cf Surface cleaning, etching, patterning
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
68.47.Mn Polymer surfaces
61.41.+e Polymers, elastomers, and plastics
42.70.Jk Polymers and organics
78.66.Qn Polymers; organic compounds

Spatial domain realization of the cavity ring-down technique in a plane Fabry–Perot cavity

Jae Yong Lee, Hai-Woong Lee, and Jae Won Hahn

Appl. Phys. Lett. 78, 1481 (2001); http://dx.doi.org/10.1063/1.1342039 (3 pages) | Cited 2 times

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We propose and demonstrate a spatial version of the cavity ring-down concept in which a photon flux decay is displayed along the spatial coordinate at the exit of a plane Fabry–Perot cavity. The photon decay signals are simulated based on a simple theoretical model combining ray optics and diffraction involved in the spatial ring-down generation, which are found to be in good accordance with the results of a proof-of-principle expermient. © 2001 American Institute of Physics.
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07.60.Rd Visible and ultraviolet spectrometers
07.60.Ly Interferometers
42.15.Dp Wave fronts and ray tracing
42.25.Fx Diffraction and scattering

Laser micromachining using liquid optics

D. Ramanathan and P. A. Molian

Appl. Phys. Lett. 78, 1484 (2001); http://dx.doi.org/10.1063/1.1351844 (3 pages) | Cited 5 times

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Lasers are well suited for micromanufacturing by ablating nearly all the material within the focal spot before any significant heat conduction or mass flow takes place, thus enabling precise machining with little thermal damage. In this letter, the results of an idea of using nonlinear liquids as lenses to fabricate micron-sized features are reported. Our research showed that transmitting the laser pulse through a transparent condensed medium such as carbon disulfide that has very high intensity-dependent nonlinear refractive index creates a lens and focuses the beam. Results on 316 stainless steel showed a two-fold decrease in the hole size and reduced taper when liquid optics were used over traditional solid optics. Polarization effects were also substantially reduced. The beneficial effects of liquid optics are explored. © 2001 American Institute of Physics.
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42.62.Cf Industrial applications
42.79.Bh Lenses, prisms and mirrors
81.20.Wk Machining, milling
06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)

Coupled guide and cavity in a two-dimensional photonic crystal

C. J. M. Smith, R. M. De La Rue, M. Rattier, S. Olivier, H. Benisty, C. Weisbuch, T. F. Krauss, R. Houdré, and U. Oesterle

Appl. Phys. Lett. 78, 1487 (2001); http://dx.doi.org/10.1063/1.1355667 (3 pages) | Cited 55 times

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We demonstrate, in a planar two-dimensional (2D) configuration, in the optical regime a clear association of two photonic crystal elements and the ability to produce a low-loss coupled system. A channel waveguide is brought to between two and five crystal rows (450 to 1126 nm) from a 2D microcavity fabricated in a GaAs/AlGaAs waveguide. We probe these two elements individually and explore their interaction. © 2001 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
85.60.Bt Optoelectronic device characterization, design, and modeling
78.67.Hc Quantum dots
42.79.Gn Optical waveguides and couplers
81.05.Ea III-V semiconductors
81.07.Ta Quantum dots
42.70.Qs Photonic bandgap materials

A photopolymerizable glass with diffraction efficiency near 100% for holographic storage

Pavel Cheben and María L. Calvo

Appl. Phys. Lett. 78, 1490 (2001); http://dx.doi.org/10.1063/1.1354665 (3 pages) | Cited 57 times

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Permanent holographic storage has been demonstrated in a photopolymerizable organically modified silica glass. The glass was prepared by dispersing a titanocene photoinitiator and a high refractive index acrylic monomer in a porous silica matrix. This glass exhibits unprecedented sensitivity and refractive index change upon a moderate exposure to green light and can be fabricated in thickness up to several millimeters. A photopolymerizable storage medium of such a thickness with good holographic properties is needed for practical holographic storage devices. Lack of such medium has been considered the main obstacle in development of write-once holographic memories. In our glass, we have stored permanent volume holograms of diffraction efficiency approaching 100% and refractive index modulation up to 4.5×10−3, making this photopolymerizable material suitable for use in holographic data storage. © 2001 American Institute of Physics.
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42.70.Ln Holographic recording materials; optical storage media
42.79.Vb Optical storage systems, optical disks
42.70.Ce Glasses, quartz
42.70.Jk Polymers and organics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
82.50.Hp Processes caused by visible and UV light
82.35.-x Polymers: properties; reactions; polymerization

Multicolor oligothiophene-based light-emitting diodes

G. Gigli, O. Inganäs, M. Anni, M. De Vittorio, R. Cingolani, G. Barbarella, and L. Favaretto

Appl. Phys. Lett. 78, 1493 (2001); http://dx.doi.org/10.1063/1.1355991 (3 pages) | Cited 35 times

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We demonstrate wide tunability, from green to near infrared, of the electroluminescence emission of substituted oligothiophene compounds. The compounds are characterized by high chemical stability, electron affinities up to 3.1 eV and photoluminescence efficiencies up to 70%. These characteristics make these materials excellent candidates for application in light-emitting diodes. We obtain low turn-on voltage devices with electroluminescence efficiency up to 0.2%, more than one order of magnitude larger than the values reported for unsubstituted oligothiophene compounds. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.55.Kz Solid organic materials
42.70.Jk Polymers and organics

High-precision ranging using a chaotic laser pulse train

Krishna Myneni, Thomas A. Barr, Billy R. Reed, Shawn D. Pethel, and Ned J. Corron

Appl. Phys. Lett. 78, 1496 (2001); http://dx.doi.org/10.1063/1.1355663 (3 pages) | Cited 13 times

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We demonstrate the use of a chaotic laser pulse train for high-precision ranging. The pulse train is produced by inducing coherence collapse in an AlGaAs semiconductor laser. Measurements of optical spectra, intensity autocorrelation functions, and ladar ranging are presented. © 2001 American Institute of Physics.
Show PACS
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR
42.55.Px Semiconductor lasers; laser diodes
42.25.Kb Coherence
42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics
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