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31 Jul 2000

Volume 77, Issue 5, pp. 609-762

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Green upconversion luminescence in Er3+:BaTiO3 films

H. X. Zhang, C. H. Kam, Y. Zhou, X. Q. Han, S. Buddhudu, Q. Xiang, Y. L. Lam, and Y. C. Chan

Appl. Phys. Lett. 77, 609 (2000); http://dx.doi.org/10.1063/1.127060 (3 pages) | Cited 35 times

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Green upconversion emissions at 548 and 528 nm have been obtained from sol-gel derived nanocrystalline Er3+:BaTiO3 films under 980 nm excitation. The green emissions are attributed to the ground-state (4I15/2) -directed transitions from 2H11/2 (528 nm) and 4S3/2 (548 nm) of Er3+ ions. Analysis of the temporal evolution of the emission at 548 nm shows that both excited state absorption of individual ion and energy transfer between the two neighboring ions contribute to the upconversion emissions in Er3+ (3 mol %):BaTiO3 film. The lifetime of the dominant emission at 548 nm is about 90 μs. © 2000 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.66.Nk Insulators
71.55.Ht Other nonmetals
61.46.-w Structure of nanoscale materials

Depolarization by high aperture focusing

K. Bahlmann and S. W. Hell

Appl. Phys. Lett. 77, 612 (2000); http://dx.doi.org/10.1063/1.127061 (3 pages) | Cited 22 times

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We introduce a method employing ferroelectric monomolecular layers, by which it is possible to measure the light field polarization in the focus of a lens. This method allowed us to noninvasively establish the perpendicularly oriented focal field that is anticipated at high apertures. For a numerical aperture 1.4 oil immersion lens illuminated with linearly polarized plane waves, the integral of the modulus square of the perpendicular component amounts to (1.51±0.2) % of that of the initial polarization. It is proven that depolarization decreases with decreasing aperture angle. Whereas for regular imaging conditions depolarization is largely negligible, it plays a significant role in microscopy of highest resolution, microspectroscopy, and single molecule studies. © 2000 American Institute of Physics.
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42.79.Bh Lenses, prisms and mirrors
42.25.Ja Polarization

2.79 μm erbium laser with lead–lanthanum zirconate titanate ceramics electro-optic Q-switching output coupler

Maris Ozolinsh and Hans J. Eichler

Appl. Phys. Lett. 77, 615 (2000); http://dx.doi.org/10.1063/1.127062 (3 pages) | Cited 6 times

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Highly refractive and transparent lead–lanthanum zirconate titanate (PLZT) ceramics are used for an output coupler of the erbium yttrium scandium gallium garnet laser (λ = 2.79 μm) that simultaneously serves as the laser electro-optic Q switch. The optical aperture of such a dual-function PLZT element was 6×6 mm2 and the thickness was 3 mm. For Q switching, short ≈3 μs negative voltage pulses (1500–1800 V) were applied to the positively direct current biased (≈1400 V) PLZT element. Single-pulse lasing with a pulse half width of 160–170 ns was observed at short and long delays of the Q switch with respect to the pump flash. The highest output energy of 20–22 mJ within 1.5–2.5 μs, consisting of two or three pulses with 130 ns half width was obtained at an intermediate delay of 90–110 μs. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
42.79.Gn Optical waveguides and couplers

Estimation of interwell terahertz gain by photon-assisted tunneling measurement in triple-barrier resonant tunneling diodes

M. Asada, Y. Oguma, and N. Sashinaka

Appl. Phys. Lett. 77, 618 (2000); http://dx.doi.org/10.1063/1.127063 (3 pages) | Cited 2 times

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Terahertz (THz) gain due to electron transition between adjacent quantum wells was estimated from a measurement of current change in triple-barrier resonant tunneling diodes under the THz irradiation. Measured current change was separated into stimulated emission and absorption components, and the gain coefficient was estimated from the difference between these components. For a sample with relatively thick barriers and peak current density of 70 A/cm2, the room-temperature peak gain coefficient was about 0.15 cm−1 at 2.24 THz. The estimated gain coefficient is in reasonable agreement with an approximate theory. High gain is expected by increasing the current density with thin barriers. © 2000 American Institute of Physics.
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78.45.+h Stimulated emission
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.55.Px Semiconductor lasers; laser diodes
85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
78.66.-w Optical properties of specific thin films

Artifact-free near-field optical imaging by apertureless microscopy

M. Labardi, S. Patanè, and M. Allegrini

Appl. Phys. Lett. 77, 621 (2000); http://dx.doi.org/10.1063/1.127064 (3 pages) | Cited 35 times

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A method for optical near field discrimination, leading to drastic artifact reduction in superresolved imaging by scanning interference apertureless microscopy is presented. The method relies on second harmonic detection of the modulated optical signal scattered by a vibrating silicon tip. An edge resolution of 15 nm, or 7 nm Rayleigh-type resolution, with optical contrast as high as 50%, has been obtained on aluminum projection pattern samples in the constant gap width mode. Our method has been determined not to be affected by topographical artifacts by constant height mode scans. © 2000 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
42.30.-d Imaging and optical processing
42.25.Hz Interference
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.25.Fx Diffraction and scattering

Enhanced degradation resistance of quantum dot lasers to radiation damage

P. G. Piva, R. D. Goldberg, I. V. Mitchell, D. Labrie, R. Leon, S. Charbonneau, Z. R. Wasilewski, and S. Fafard

Appl. Phys. Lett. 77, 624 (2000); http://dx.doi.org/10.1063/1.127065 (3 pages) | Cited 28 times

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We compare the degradation of InAs/GaAs quantum well (QW) and quantum dot (QD) laser diodes following irradiation by high energy (8.56 MeV) phosphorous ions. Over a fluence range of 108–1011 ions/cm2, the degradation of the low temperature QD photoluminescence and electroluminescence emission is greatly suppressed relative to that of QW based devices (×100 and ×1000, respectively at the highest dose studied). Irradiated QD laser diodes demonstrated lasing action over the entire range of fluences, and 2 orders of magnitude beyond the maximum dose sustainable by QW devices. The improved damage response of QD based structures results from efficient collection and localization of electrons and holes by QDs in the active region, which limit carrier transfer to nonradiative centers. This work suggests the suitability of QD device architectures for use in radiation environments, and in high power applications, wherever nonradiative processes promote the degradation or failure of traditional QW devices. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.60.Fi Electroluminescence
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

High-quality phase conjugation even in a highly transient regime of stimulated Brillouin scattering

B. Králiková, J. Skála, P. Straka, and H. Turčičová

Appl. Phys. Lett. 77, 627 (2000); http://dx.doi.org/10.1063/1.127066 (3 pages) | Cited 1 time

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A high-quality phase conjugation of the stimulated Brillouin scattering has been achieved even in a highly transient regime, as proved by the mask restoration in the backscattered signal. A special two-lens system of laser beam insertion into a scattering medium was used. A reliable onset of the phase conjugation has been reached using a splitted part of the oscillator Q-switched pulse as a prepulse in the Brillouin cell. Results with and without the prepulse are compared. A possibility of the creation of the phase conjugated mirrors even in high-power gaseous lasers with short pulses is thus proved. © 2000 American Institute of Physics.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.79.Bh Lenses, prisms and mirrors
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers

Gain in 1.3 μm materials: InGaNAs and InGaPAs semiconductor quantum-well lasers

J. Hader, S. W. Koch, J. V. Moloney, and E. P. O’Reilly

Appl. Phys. Lett. 77, 630 (2000); http://dx.doi.org/10.1063/1.127067 (3 pages) | Cited 46 times

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The absorption and gain for an InGaNAs/GaAs quantum-well structure is calculated and compared to that of a more conventional InGaAs/InGaPAs structure, both lasing in the 1.3 μm range. Despite significant differences in the band structures, the gain value is comparable for high carrier densities in both structures and the transition energy at the gain maximum shows a similar blueshift with increasing carrier density. For low and intermediate carrier densities, the calculated gain in the InGaPAs system is significantly lower and the bandwidth smaller than in the InGaNAs system. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.45.+h Stimulated emission
73.61.Ey III-V semiconductors
78.66.Fd III-V semiconductors

Experimental observation of the mobility edge in a waveguide with correlated disorder

U. Kuhl, F. M. Izrailev, A. A. Krokhin, and H.-J. Stöckmann

Appl. Phys. Lett. 77, 633 (2000); http://dx.doi.org/10.1063/1.127068 (3 pages) | Cited 98 times

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The tight-binding model with correlated disorder introduced by Izrailev and Krokhin [Phys. Rev. Lett. 82, 4062 (1999)] has been extended to the Kronig–Penney model. The results of the calculations have been compared with microwave transmission spectra through a single-mode waveguide with inserted correlated scatterers. All predicted bands and mobility edges have been found in the experiment, thus demonstrating that any wanted combination of transparent and nontransparent frequency intervals can be realized experimentally by introducing appropriate correlations between scatterers. © 2000 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
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