APL: Lasers, Optics, and Optoelectronics

Characterization of blue-green m-plane InGaN light emitting diodes

You-Da Lin, Arpan Chakraborty, Stuart Brinkley, Hsun Chih Kuo, Thiago Melo et al.
High indium content blue-green (460520 nm) m-plane InGaN light emitting diodes (LEDs) were grown on low defect-density m-plane GaN substrates. Systematic studies were performed on packaged blue-green LED lamps by using a range of well and barrier thicknesses. Photoluminance and electroluminance peak ... [Appl. Phys. Lett. 94, 261108 (2009)] published Wed Jul 1, 2009.

Flexible Ge-on-polyimide detectors

W. S. Ho, Y.-H. Dai, Y. Deng, C.-H. Lin, Y.-Y. Chen et al.
A flexible Ge-on-polyimide photodetector is demonstrated. The single crystalline thin film of Ge was transferred on the polyimide by adhesive wafer bonding and smart-cut techniques. A simple tunneling metal-oxide-semiconductor structure is fabricated for the detector applications. Due to the transpa ... [Appl. Phys. Lett. 94, 261107 (2009)] published Wed Jul 1, 2009.

Photocurrent properties of freely suspended carbon nanotubes under uniaxial strain

S. M. Kaniber, L. Song, J. P. Kotthaus, and A. W. Holleitner
The photocurrent properties of freely suspended single-walled carbon nanotubes (CNTs) are investigated as a function of uniaxial strain. We observe that at low strain, the photocurrent signal of the CNTs increases for increasing strain, while for large strain, the signal decreases, respectively. We ... [Appl. Phys. Lett. 94, 261106 (2009)] published Wed Jul 1, 2009.

Silver halide single mode fibers for broadband middle infrared stellar interferometry

T. Lewi, A. Tsun, A. Katzir, J. Kaster, and F. Fuchs
We report the demonstration of silver halide single mode fibers at lambda=7.5 [mu]m. The fiber's modal behavior was tested at lambda=10.6 and lambda=7.5 [mu]m, using near field measurements. Single mode operation was observed for both wavelengths with propagation losses of ~16 and ~40 dB/m at lam ... [Appl. Phys. Lett. 94, 261105 (2009)] published Mon Jun 29, 2009.

Temperature dependences of photoluminescence and electroluminescence spectra in light-emitting diodes

Lian Li, Ping Li, Yumei Wen, Jing Wen, and Yong Zhu
The temperature influence on the luminescence characteristics of light-emitting diodes (LEDs) is investigated to reveal the connection of photoluminescence (PL) with photon absorption and electroluminescence (EL) through current injection. By inspecting the PL and EL spectra at identical injection i ... [Appl. Phys. Lett. 94, 261103 (2009)] published Mon Jun 29, 2009.

In situ passivation and blue luminescence of silicon clusters using a cluster beam/HO codeposition production method

A. Brewer and K. von Haeften
Si clusters are produced in a gas aggregation source and fly through ultrahigh vacuum onto a cold target where they are codeposited with water vapor. Melting of the ice yields immediately a suspension of nanoparticles that emits intense, nondegrading luminescence in the blue wavelength range. Spectr ... [Appl. Phys. Lett. 94, 261102 (2009)] published Mon Jun 29, 2009.

200 mW type I GaSb-based laser diodes operating at 3 [mu]m: Role of waveguide width

Takashi Hosoda, Gela Kipshidze, Leon Shterengas, Sergey Suchalkin, and Gregory Belenky
Laser diodes based on AlInGaAsSb/InGaAsSb heterostructures with different waveguide widths were designed and fabricated. The decrease in the waveguide width from 1470 to 470 nm led to the improvement of the device performance. Lasers with 470 nm quinternary waveguides demonstrated 200 mW continuous ... [Appl. Phys. Lett. 94, 261104 (2009)] published Mon Jun 29, 2009.

Nonlinear optical infrared microscopy with chemical specificity

Eun Seong Lee and Jae Yong Lee
We demonstrate a realization of nonlinear optical infrared microscopy that is capable of chemically specific imaging with high spatial resolution. It exploits the nonlinear refraction of the target material that is thermally induced by resonantly absorbed mid-infrared radiation and probed with a sho ... [Appl. Phys. Lett. 94, 261101 (2009)] published Mon Jun 29, 2009.

Observation of whispering gallery modes in nonpolar m-plane GaN microdisks

Adele C. Tamboli, Mathew C. Schmidt, Asako Hirai, Steven P. DenBaars, and Evelyn L. Hu
We have fabricated nonpolar GaN/InGaN microdisks using band-gap selective photoelectrochemical etching. These microdisks have a smoother optical cavity than our previous c-plane microdisks, and they support whispering gallery modes with quality factors as high as 2000 after a focused ion beam treatm ... [Appl. Phys. Lett. 94, 251116 (2009)] published Fri Jun 26, 2009.

The role of optical rectification in the generation of terahertz radiation from GaBiAs

K. Radhanpura, S. Hargreaves, R. A. Lewis, and M. Henini
We report on a detailed study of the emission of terahertz-frequency electromagnetic radiation from layers of GaBiAs (0<=y<0.04) grown by molecular beam epitaxy on (311)B and (001) GaAs substrates. We measure two orthogonally polarized components of the terahertz radiation emitted under excitation b ... [Appl. Phys. Lett. 94, 251115 (2009)] published Fri Jun 26, 2009.

Quantum cascade lasers with voltage defect of less than one longitudinal optical phonon energy

Matthew D. Escarra, Anthony J. Hoffman, Kale J. Franz, Scott S. Howard, Richard Cendejas et al.
Efficient use of applied voltage in quantum cascade (QC) lasers is a critical factor in achieving high wall-plug efficiency and low compliance voltage. We demonstrate a QC laser emitting at 4.2 [mu]m featuring a low voltage defect and short injector with only four quantum wells. Devices with a volt ... [Appl. Phys. Lett. 94, 251114 (2009)] published Thu Jun 25, 2009.

On the temperature dependence of point-defect-mediated luminescence in silicon

Daniel Recht, Federico Capasso, and Michael J. Aziz
We present a model of the temperature dependence of point-defect-mediated luminescence in silicon derived from basic kinetics and semiconductor physics and based on the kinetics of bound exciton formation. The model provides a good fit to data for W line electroluminescence and G line photoluminesce ... [Appl. Phys. Lett. 94, 251113 (2009)] published Thu Jun 25, 2009.

Pumping of atomic alkali lasers by photoexcitation of a resonance line blue satellite and alkali-rare gas excimer dissociation

J. D. Readle, C. J. Wagner, J. T. Verdeyen, T. M. Spinka, D. L. Carroll et al.
Photoassociation of alkali-rare gas atomic collision pairs provides an alternative approach to optically pumping atomic alkali lasers. Lasing on the 6 P-->6 S (D) transition of Cs has been observed when the blue satellite of the 6 P<--6 S (D) transition, peaking at ~837 nm for mixtures of Cs vapor, ... [Appl. Phys. Lett. 94, 251112 (2009)] published Wed Jun 24, 2009.

An air-slotted nanoresonator relying on coupled high Q small V FabryPerot nanocavities

Kevin Foubert, Loic Lalouat, Benoit Cluzel, Emmanuel Picard, David Peyrade et al.
We study here the lateral evanescent coupling between photonic crystals cavities. The structure consists in two identical monomode FabryPerot nanocavities, integrated on silicon-on-insulator slot-waveguides (WG). Spectral and optical near field measurements were led and supported quantitatively by t ... [Appl. Phys. Lett. 94, 251111 (2009)] published Wed Jun 24, 2009.

Evaluation of the optical axis tilt of zinc oxide films via noncollinear second harmonic generation

F. A. Bovino, M. C. Larciprete, A. Belardini, and C. Sibilia
We investigated noncollinear second harmonic generation form zinc oxide films, grown on glass substrates by dual ion beam sputtering technique. At a fixed incidence angle, the generated signal is investigated by scanning the polarization state of both fundamental beams. We show that the map of the g ... [Appl. Phys. Lett. 94, 251109 (2009)] published Tue Jun 23, 2009.

Terahertz time domain spectroscopy of phonon-depopulation based quantum cascade lasers

N. Jukam, S. S. Dhillon, D. Oustinov, J. Madeo, J. Tignon et al.
The gain and loss in a terahertz quantum cascade laser based on a longitudinal optical phonon depopulation scheme is studied using terahertz time domain spectroscopy. At laser threshold the gain is found to be clamped at 25 cm for a 1 mm long device and the full width at half maximum of the spectra ... [Appl. Phys. Lett. 94, 251108 (2009)] published Tue Jun 23, 2009.

Simple method of light-shift suppression in optical pumping systems

B. H. McGuyer, Y.-Y. Jau, and W. Happer
We report a simple method to suppress the light shift in optical pumping systems. This method uses only frequency modulation of a radio frequency or microwave source, which is used to excite an atomic resonance, to simultaneously lock the source frequency to the atomic resonance and lock the pumping ... [Appl. Phys. Lett. 94, 251110 (2009)] published Tue Jun 23, 2009.

Fluorescence diffuse optical tomography using upconverting nanoparticles

Can T. Xu, Johan Axelsson, and Stefan Andersson-Engels
Fluorescence diffuse optical tomography (FDOT) can provide important information in biomedical studies. In this ill-posed problem, suppression of background tissue autofluorescence is of utmost importance. We report a method for autofluorescence-insensitive FDOT using nonlinear upconverting nanopart ... [Appl. Phys. Lett. 94, 251107 (2009)] published Tue Jun 23, 2009.

Subpicosecond quantum dot saturable absorber mode-locked semiconductor disk laser

Keith G. Wilcox, Mantas Butkus, Ian Farrer, David A. Ritchie, Anne Tropper et al.
We report the generation of subpicosecond pulses from a passively mode locked, optically pumped quantum well semiconductor disk laser using a quantum dot semiconductor saturable absorber mirror (SESAM). We obtained 870 fs pulses at a repetition rate of 895 MHz with average output power of 45 mW at 1 ... [Appl. Phys. Lett. 94, 251105 (2009)] published Mon Jun 22, 2009.

Metamaterials for optical security

A. Martinez, C. Garcia-Meca, R. Ortuno, F. J. Rodriguez-Fortuno, and J. Marti
In this letter we introduce the concept of optical security marks based on photonic metamaterials. We propose that a metamaterial with strong negative magnetic activity in the visible wavelength regime can be used to create a security mark that can be incorporated in any object to ensure its authent ... [Appl. Phys. Lett. 94, 251106 (2009)] published Mon Jun 22, 2009.

Direct measurement of transient electric fields induced by ultrafast pulsed laser irradiation of silicon

H. Park and J. M. Zuo
We use 30 kV electron pulses to probe transient electric fields above silicon surfaces by pump-probe. Electron beam deflection at 0.29 mm away from the sample surface on the order of 10 degrees is measured as a function of time delay and used to measure the local electric fields. The measured field ... [Appl. Phys. Lett. 94, 251103 (2009)] published Mon Jun 22, 2009.

Excitation of propagating surface plasmons by a periodic nanoparticle array: Trade-off between particle-induced near-field excitation and damping

Amitabh Ghoshal and Pieter G. Kik
The excitation of propagating surface plasmons (SPs) on a silver-silica interface by an array of ellipsoidal silver nanoparticles is investigated using numerical simulations as a function of particle volume for three different nanoparticle aspect ratios with representative resonance frequencies. We ... [Appl. Phys. Lett. 94, 251102 (2009)] published Mon Jun 22, 2009.

Femtosecond laser induced plasma diffraction gratings in air as photonic devices for high intensity laser applications

S. Suntsov, D. Abdollahpour, D. G. Papazoglou, and S. Tzortzakis
The creation of volume plasma density gratings in air by temporally overlapped high-intensity IR femtosecond laser pulses is demonstrated experimentally. Through the diffraction of various probe beams the plasma grating properties are recovered including its thickness and refractive index modulation ... [Appl. Phys. Lett. 94, 251104 (2009)] published Mon Jun 22, 2009.

Directional emission and universal far-field behavior from semiconductor lasers with limacon-shaped microcavity

Changling Yan, Qi Jie Wang, Laurent Diehl, Martina Hentschel, Jan Wiersig et al.
We report experimental demonstration of directional light emission from limacon-shaped microcavity semiconductor lasers. Quantum cascade lasers (QCLs) emitting at lambda[approximate]10 [mu]m are used as a model system. Both ray optics and wave simulations show that for deformations in the range 0.3 ... [Appl. Phys. Lett. 94, 251101 (2009)] published Mon Jun 22, 2009.