APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Next Issue

4 Jul 2005

Volume 87, Issue 1, Articles (01xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 87, 013110 (2005); http://dx.doi.org/10.1063/1.1977187 (3 pages)

R. C. Wang, C. P. Liu, J. L. Huang, S.-J. Chen, Y.-K. Tseng, and S.-C. Kung
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Reduction of the internal electric field in wurtzite a-plane GaN self-assembled quantum dots

N. Garro, A. Cros, J. A. Budagosky, A. Cantarero, A. Vinattieri, M. Gurioli, S. Founta, H. Mariette, and B. Daudin

Appl. Phys. Lett. 87, 011101 (2005); http://dx.doi.org/10.1063/1.1977210 (3 pages) | Cited 21 times

Online Publication Date: 27 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a study of the emission of GaN/AlN self-assembled quantum dots grown on a-plane 6H-SiC showing evidence of the suppression of the internal electric field. The strain in dots and barriers is determined by means of Raman scattering and the induced piezoelectric polarizations are estimated. These reveal a compensation of the spontaneous polarization and justify the lack of a quantum confined Stark effect found in the photoluminescence spectra. Strain effects and strong confinement are responsible for the partial depolarization of the emission and its energy dependence.
Show PACS
73.63.Kv Quantum dots
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
78.67.Hc Quantum dots
78.30.Fs III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
68.65.Hb Quantum dots (patterned in quantum wells)
77.65.Ly Strain-induced piezoelectric fields
77.22.Ej Polarization and depolarization

Switching mirror in the CdTe-based photonic crystal

Michael Cada

Appl. Phys. Lett. 87, 011102 (2005); http://dx.doi.org/10.1063/1.1954876 (3 pages) | Cited 1 time

Online Publication Date: 28 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Theoretical investigations, modeling and design of a Bragg mirror (photonic crystal structure) in the CdTe-based material system are presented. It is shown that, in addition to the third-order nonlinearity (Kerr-like effect), the two-photon absorption and the resulting free-carrier refraction have to be included in the analysis and design. Inclusion of changes in the refractive index with the square of the light intensity (fifth-order nonlinearity) leads to desirable functional features of the switching mirror. The analysis provides insight into the complex nonlinear effects and serves as a tool for designing a nonlinear intra-cavity mirror for a novel pulsed laser.
Show PACS
42.79.Bh Lenses, prisms and mirrors
42.15.Eq Optical system design
42.70.Qs Photonic bandgap materials
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.25.Gy Edge and boundary effects; reflection and refraction
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Ultraviolet direct printing of rare-earth-doped polymer waveguide amplifiers

W. H. Wong, K. S. Chan, and E. Y. B. Pun

Appl. Phys. Lett. 87, 011103 (2005); http://dx.doi.org/10.1063/1.1968422 (3 pages) | Cited 11 times

Online Publication Date: 28 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polymer channel waveguide amplifier arrays were fabricated using ultraviolet direct printing methodology. The effects of different weight percentage (wt. %) combinations of rare-earth ions erbium (Er3+) and ytterbium (Yb3+) on the absorption spectrum, as well as the internal gain, were investigated. With an input signal power of ∼ −18 dBm, the highest internal gain obtained is ∼ 16.5 dB at a wavelength of 1533 nm for a 20 mm long multimode channel waveguide codoped with ∼ 1 wt. % of Er3+ and ∼ 10 wt. % of Yb3+ derivatives. The UV direct printing methodology opens a simple platform for the fabrication of dense and compact polymer waveguide laser arrays.
Show PACS
42.86.+b Optical workshop techniques
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Active Q-switched distributed feedback erbium-doped fiber lasers

P. Pérez-Millán, J. L. Cruz, and M. V. Andrés

Appl. Phys. Lett. 87, 011104 (2005); http://dx.doi.org/10.1063/1.1990252 (3 pages) | Cited 13 times

Online Publication Date: 28 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter presents a distributed feedback fiber laser that operates in an actively controlled Q-switched regime. The laser is based on a Bragg grating made in an erbium-doped fiber. The grating has a defect induced by a magnetostrictive transducer that configures the distributed feedback laser structure. The phase shift generated by the defect can be dynamically modified by an electric current, permitting active Q-switching of the laser. The laser generates pulses of 75 ns duration and the repetition rate can be continuously adjusted from 0 to 10 kHz.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Wd Fiber lasers
42.60.By Design of specific laser systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Observation of far-infrared emission from excited cytosine molecules

Y. C. Shen, P. C. Upadhya, E. H. Linfield, and A. G. Davies

Appl. Phys. Lett. 87, 011105 (2005); http://dx.doi.org/10.1063/1.1968412 (3 pages) | Cited 8 times

Online Publication Date: 29 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a time-resolved investigation of the resonant absorption of far-infrared radiation and the subsequent vibrational relaxation processes in a sample of polycrystalline cytosine at 4 K, using terahertz time-domain spectroscopy. The subpicosecond time resolution achieved in our experiments corresponds to a near single-cycle of far-infrared radiation, and this enables us to observe the damped oscillations of the electric field produced by excited molecules as they decay. Furthermore, we show that the progressive absorption and subsequent emission of far-infrared radiation at the frequency of the corresponding vibrational mode can be followed directly as a function of time by means of time-partitioned Fourier transforms of the transmitted signal.
Show PACS
33.20.Ea Infrared spectra
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
31.50.Df Potential energy surfaces for excited electronic states
33.15.Mt Rotation, vibration, and vibration-rotation constants

Transflective spatial filter based on azo-dye-doped cholesteric liquid crystal films

Tsung-Hsien Lin and Andy Y.-G. Fuh

Appl. Phys. Lett. 87, 011106 (2005); http://dx.doi.org/10.1063/1.1990248 (3 pages) | Cited 4 times

Online Publication Date: 29 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This work demonstrates the feasibility of exploiting the photoisomerization effect in azo-dye-doped cholesteric liquid crystal (DDCLC) films with a concomitant decline of the phase transition temperature from the cholesteric to an isotropic phase (TCh‐I) as a spatial filter. The fabrication depends on the fact that the various intensities of the diffracted orders are responsible for the various degrees of transparency associated with the photoisomerized DDCLC film. High- and low-pass images in the Fourier optical signal process can be simultaneously observed via reflected and transmitted signals, respectively. A simulation is also performed, and the results are consistent closely with experimental data.
Show PACS
42.79.Ci Filters, zone plates, and polarizers
42.70.Df Liquid crystals
61.30.-v Liquid crystals
64.70.M- Transitions in liquid crystals
42.30.Kq Fourier optics
78.66.Qn Polymers; organic compounds
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
82.50.-m Photochemistry

Electro-optic phase modulator using metal-defined polymer optical waveguide

Seong-Ku Kim, W. Yuan, K. Geary, Yu-Chueh Hung, H. R. Fetterman, Dong-Gun Lee, C. Zhang, C. Wang, W. H. Steier, G.-C. Park, S.-J. Kang, and I. Oh

Appl. Phys. Lett. 87, 011107 (2005); http://dx.doi.org/10.1063/1.1991998 (3 pages) | Cited 4 times

Online Publication Date: 30 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate metal-defined electro-optic polymer phase modulators for the first time. A metal strip patterned on top of a three-layer slab waveguide causes a strain-induced refractive index change, resulting in lateral optical mode confinement within the core layer. The strain profile, refractive indexes, and optical mode shapes of the metal defined optical waveguide are obtained analytically. Electro-optic phase modulators fabricated using this technique have a driving voltage of 5.6 V, and ∼ 18 dB of extinction ratio at 1.55 μm wavelength. These results may be used in the complex design of integrated polymer optical circuits that require a simple and cheap fabrication process.
Show PACS
42.79.Hp Optical processors, correlators, and modulators
42.82.Et Waveguides, couplers, and arrays
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Gn Optical waveguides and couplers
42.70.Jk Polymers and organics

Electro-optic characteristics and switching principle of a single-cell-gap transflective liquid-crystal display associated with in-plane rotation of liquid crystal driven by a fringe-field

J. H. Song, Y. J. Lim, M.-H. Lee, S. H. Lee, and S. T. Shin

Appl. Phys. Lett. 87, 011108 (2005); http://dx.doi.org/10.1063/1.1991981 (3 pages) | Cited 34 times

Online Publication Date: 30 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A single-gap transflective liquid-crystal (LC) display associated with in-plane rotation of the LC director was designed. In the device, a fringe electric field drives to rotate a homogeneously aligned LC in plane to optimize polarization efficiency. Rotating degrees of the LC director, 22.5° and 45° were required in both reflective and transmissive regions, respectively. In the device, the cell gap was the same for both regions, and a dark state was irrespective of the cell retardation value at normal direction, which was highly important in massive fabrications. The switching principle and electro-optic characteristics of the device are reported herein.
Show PACS
42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems
42.70.Df Liquid crystals
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order

Low-power, multiport, ultrafast, parametric switching in cascaded waveguide couplers

Roland Schiek, Robert Iwanow, George Stegeman, Thomas Pertsch, Falk Lederer, Yoo Hong Min, and Wolfgang Sohler

Appl. Phys. Lett. 87, 011109 (2005); http://dx.doi.org/10.1063/1.1991993 (3 pages)

Online Publication Date: 30 June 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We explore an approach to multiport, phase-insensitive all-optical switching of milliwatt power signals based on linear coupling in cascaded directional couplers and on nonlinear parametric gain via the second-order nonlinearity. For the basic unit, a two-core coupler, we experimentally demonstrated ultrafast transparent switching of 1550 nm signals triggered by 5-ps-long control pulses at ≈ 775 nm with a peak power of 1.3 W. Theoretically, we show that this concept has the potential for terabit/s switching with a few picojoules control energy and without pulse degradation.
Show PACS
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Tensile strained Ge p-i-n photodetectors on Si platform for C and L band telecommunications

Jifeng Liu, Douglas D. Cannon, Kazumi Wada, Yasuhiko Ishikawa, Samerkhae Jongthammanurak, David T. Danielson, Jurgen Michel, and Lionel C. Kimerling

Appl. Phys. Lett. 87, 011110 (2005); http://dx.doi.org/10.1063/1.1993749 (3 pages) | Cited 41 times

Online Publication Date: 1 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a 0.25% tensile strained Ge p-i-n photodetector on Si platform that effectively covers both C and L bands in telecommunications. The direct band edge of the Ge film has been pushed from 1550 to 1623 nm with 0.25% tensile strain, enabling effective photon detection in the whole L band. The responsivities of the device at 1310, 1550, and 1620 nm are 600, 520, and 100 mA/W under 0 V bias, which can be further improved to 980, 810, and 150 mA/W with antireflection coating based on calculations. Therefore, the device covers the whole wavelength range used in telecommunications. The responsivities at 1310 and 1550 nm are comparable to InGaAs photodetectors currently used in telecommunications. In the spectrum range of 1300–1650 nm, maximum responsivity was already achieved at 0 V bias because carrier transit time is much shorter than carrier recombination life time, leading to ∼ 100% collection efficiency even at 0 V bias. This is a desirable feature for low voltage operation. The absorption coefficients of 0.25% tensile strained Ge in the L band have been derived to be nearly an order of magnitude higher than bulk Ge. The presented device is compatible with conventional Si processing, which enables monolithic integration with Si circuitry.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.60.Dw Photodiodes; phototransistors; photoresistors

Use of patterned laser liftoff process and electroplating nickel layer for the fabrication of vertical-structured GaN-based light-emitting diodes

Shui-Jinn Wang, Kai-Ming Uang, Shiue-Lung Chen, Yu-Cheng Yang, Shu-Cheng Chang, Tron-Min Chen, Chao-Hsuing Chen, and Bor-Wen Liou

Appl. Phys. Lett. 87, 011111 (2005); http://dx.doi.org/10.1063/1.1993757 (3 pages) | Cited 45 times

Online Publication Date: 1 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The fabrication process and performance characteristics of a vertical-structured GaN-based light-emitting diode (VM-LED) employing nickel electroplating and patterned laser liftoff techniques are presented. As compared to regular LED, the forward voltage drop of the VM-LED at 20–80 mA is about 10%–21% lower, while the light output power (Lop) is more than twice in magnitude. Especially, the Lop exhibits no saturation or degradation at an injection current up to 520 mA which is about 4.3 times higher than that of the regular one. Substantial improvements in the VM-LEDs performances are mainly attributed to the use of metallic substrate which results in less current crowding, larger effective area, and higher thermal conductivity.
Show PACS
85.60.Jb Light-emitting devices
42.62.-b Laser applications
81.15.Pq Electrodeposition, electroplating
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close