Online ISSN
1751-8776
Print ISSN
1751-8768
IET Optoelectronics
Volume 3, Issue 6, December 2009
Volumes & issues:
Volume 3, Issue 6
December 2009
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- Author(s): P. Smowton
- Source: IET Optoelectronics, Volume 3, Issue 6, page: 241 –241
- DOI: 10.1049/iet-opt.2009.9052
- Type: Article
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- Author(s): F. Grillot ; N.A. Naderi ; M. Pochet ; C.-Y. Lin ; P. Besnard ; L.F. Lester
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 242 –247
- DOI: 10.1049/iet-opt.2009.0037
- Type: Article
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The onset of the coherence collapse (CC) regime, which is incompatible with data transmission, is investigated both theoretically and experimentally in a 1.55-µm InAs/InP quantum dash semiconductor laser. It is numerically shown that the filling from the excited state produces an additional term, which accelerates the route to chaos. This contribution can be seen as a perturbation that reduces the overall CC threshold. - Author(s): Q. Zhuang and A. Krier
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 248 –258
- DOI: 10.1049/iet-opt.2009.0034
- Type: Article
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The molecular beam epitaxial (MBE) growth and spectroscopy of dilute nitride InAsN:Sb epilayers are presented. Nitrogen incorporation in InAsN epilayers grown by radio-frequency plasma-assisted MBE was investigated as a function of growth conditions. High-quality InAsN epilayers containing up to 2.5% nitrogen were successfully grown using optimal growth conditions. The optical properties of InAsN were studied by photoluminescence (PL). Intense PL emission at 4 K was observed with double-peak features, which were attributed to free carrier recombination and localised carrier recombination. Strong room temperature PL emission extending up to a wavelength of 4.5 µm was obtained and a bandgap reduction of 63 meV for 1% N was deduced. The electronic properties of InAsN such as residual carrier concentration and mobility were also studied by Hall effect measurements. Further improvement of InAsN by addition of Sb during growth is also discussed. The authors observed that the introduction of Sb flux dramatically enhances nitrogen incorporation and significantly improves optical properties. In addition, Sb incorporation is enhanced with the presence of nitrogen. The authors also report the realisation of InAsN:Sb/InAs mid-infrared light emitting diodes operating at 4.0 µm at 4 K. - Author(s): S. Arafin ; A. Bachmann ; K. Kashani-Shirazi ; S. Priyabadini ; M.-C. Amann
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 259 –263
- DOI: 10.1049/iet-opt.2009.0038
- Type: Article
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The authors present low-resistive ohmic contacts to lattice-matched n-type InAsSb on n-GaSb substrates, which are suitable for GaSb-based devices. Using wet chemical treatment as a surface preparation in order to remove the native oxides and evaporating Ti/Pt/Au metals sequentially, specific contact resistivities as low as 5.6×10−6 Ω cm2 without any annealing are obtained. The resistivity decreases to 3.7×10−6 Ω cm2 after annealing at 350°C for 90 s. - Author(s): M.F.O. Hameed ; S.S.A. Obayya ; K. Al Begain ; A.M. Nasr ; M.I. Abo el Maaty
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 264 –273
- DOI: 10.1049/iet-opt.2009.0033
- Type: Article
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This study presents the coupling characteristics of a novel soft glass photonic crystal fibre (PCF) coupler infiltrated with a nematic liquid crystal (NLC–PCF). The soft glass provides optical properties that cannot be obtained by silica such as high refractive index, high rare earth solubility and mid-infrared transmission. In addition, the nematic liquid crystal (NLC) offers high tunability with the temperature and external electric field, and increases the birefringence between the two fundamental polarised modes in the proposed coupler. Therefore the NLC–PCF coupler has stronger polarisation dependence than the low birefringence conventional silica PCF coupler. The effects of the coupler geometrical parameters, rotation angle of the director of the NLC and temperature on the coupler performance are investigated. The analysis is carried out using the full vectorial finite difference method and the beam propagation study is performed by the full vectorial finite difference beam propagation method. The numerical results reveal that the polarisation dependence of NLC–PCF coupler is approximately 2.5 times that of the conventional silica PCF coupler with shorter coupling length. In addition, the NLC–PCF coupler has strong potential to offer practical design for short polarisation splitter as well as multiplexer–demultiplexer. - Author(s): E.M. Shahverdiev and K.A. Shore
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 274 –282
- DOI: 10.1049/iet-opt.2009.0025
- Type: Article
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The authors report on partial and global generalised synchronisation in exemplar bi-directionally coupled non-identical chaotic systems with multiple time delays. The authors derive conditions for such synchronisation regimes. The general approach is applied to the case of multiple time-delay laser systems with electro-optical feedback. The authors also study the effect of signal sampling on the signatures of time delays in the autocorrelation function of the multiple time-delay laser output. - Author(s): H.P. Zhao ; G.Y. Liu ; X.-H. Li ; R.A. Arif ; G.S. Huang ; J.D. Poplawsky ; S. Tafon Penn ; V. Dierolf ; N. Tansu
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 283 –295
- DOI: 10.1049/iet-opt.2009.0050
- Type: Article
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Staggered InGaN quantum wells (QWs) are investigated both numerically and experimentally as improved active region for light-emitting diodes (LEDs) emitting at 520–525 nm. Based on a self-consistent six-band k·p method, band structures of both two-layer staggered InxGa1−xN/InyGa1−yN QW and three-layer staggered InyGa1−yN/InxGa1−xN/InyGa1−yN QW structures are investigated as active region to enhance the spontaneous emission radiative recombination rate (Rsp) for LEDs emitting at 520–525 nm. Numerical analysis shows significant enhancement of Rsp for both two-layer and three-layer staggered InGaN QWs as compared to that of the conventional InzGa1−zN QW. Significant reduction of the radiative carrier lifetime contributes to the enhancement of the radiative efficiency for both two-layer and three-layer staggered InGaN QW LEDs emitting at 520–525 nm. Three-layer staggered InGaN QW LEDs emitting at 520–525 nm was grown by metal-organic chemical vapour deposition (MOCVD) by employing graded-temperature profile. Power density-dependent cathodoluminescence (CL) measurements show the enhancement of peak luminescence by up to 3 times and integrated luminescence by 1.8–2.8 times for the three-layer staggered InGaN QW LED. Electroluminescence (EL) output power of the staggered InGaN QW LED exhibits 2.0–3.5 times enhancement as compared to that of the conventional InGaN QW LED. The experimental results show the good agreement with theory. - Author(s): B. Royall and N. Balkan
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 296 –299
- DOI: 10.1049/iet-opt.2009.0035
- Type: Article
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The authors simulate both conventional and doping superlattice GaInNAs solar cells. They show that for a conventional cell with 1 µm diffusion lengths the maximum possible efficiency is approximately 9.5% and for 0.1 µm diffusion lengths it is 6.5% as the device must be relatively thin. Doping superlattice structures with varying number of layers and different layer thicknesses are simulated to find the design which yields the highest efficiency. A high number of thin layers allow a high percentage of incident photons to be absorbed, and carrier separated increasing the short-circuit currents leading to efficiencies close to 12%. - Author(s): Chin-Yi Tsai and Chin-Yao Tsai
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 300 –304
- DOI: 10.1049/iet-opt.2009.0027
- Type: Article
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A theoretical model is proposed to study the effects of carrier escape and capture processes on the photocurrent of quantum well solar cells (QWSCs). The results show that solar cells with very deep quantum wells (QWs) will suffer from extremely slow escape processes and their photocurrent can be inferior to their bulk counterparts. The results suggest that only when the escape time is at least two-order of magnitude smaller than the carrier lifetime of QWs, solar cells will benefit from QW structures. The optimal band gap energies of QW materials for achieving the maximum photocurrent are also calculated and discussed. - Author(s): A.B. Ikyo ; I.P. Marko ; A.R. Adams ; S.J. Sweeney ; A. Bachmann ; K. Kashani-Shirazi ; M.-C. Amann
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 305 –309
- DOI: 10.1049/iet-opt.2009.0045
- Type: Article
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High-pressure techniques are used to investigate and optimise the design of GaInAsSb/AlGaAsSb vertical cavity surface emitting lasers (VCSELs) emitting at 2.4 µm. From measurements on edge emitting lasers it is found that non-radiative Auger recombination accounts for up to 85% of the threshold current at room temperature (RT) and is responsible for their strong temperature sensitivity. The effect of Auger recombination in VCSELs may be mitigated through judicious design of the gain peak–cavity mode (CM) alignment which may be investigated using high pressure. Results show that temperature insensitivity over the range −10 to +30°C may be obtained around RT if the gain peak is offset by approximately 10 meV higher in energy from the VCSEL CM. - Author(s): A.M. Matarneh and S.S.A. Obayya
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 310 –319
- DOI: 10.1049/iet-opt.2009.0030
- Type: Article
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This study introduces an accurate non-linear distortion analysis for vertical cavity surface emitting lasers (VCSELs) based on Volterra series approach in directly modulated scheme. Closed-form expressions of the optical response of VCSELs in terms of modulation response, harmonic distortions, and second- and third-order intermodulation distortions are derived. The impact of external optical feedback on the VCSEL's response and intermodulation distortion is investigated. Moreover, the suggested non-linear model avoids the numerical solution of laser rate equations and provides in detail a non-linear distortion analysis of VCSELs. - Author(s): G. Blume ; C. Fiebig ; D. Feise ; C. Kaspari ; A. Sahm ; K. Paschke ; G. Erbert
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 320 –325
- DOI: 10.1049/iet-opt.2009.0042
- Type: Article
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Small-sized modules that have an output power P>100 mW with a spectral width <0.25 pm at 15°C are presented. The modules, aimed at HeNe laser applications, are stabilised at 632.8 nm with reflective volume Bragg gratings at the rear side of a tapered gain medium. The gain medium consists of AlGaInP layers grown on GaAs with metal-organic vapour-phase epitaxy, which allows for an emission between 629 and 636 nm in an external cavity configuration. Free running tapered lasers from the same material achieve a room temperature continuous wave emission P>400 mW near 633 nm and operate for more than 1000 h at 200 mW. - Author(s): E.M. Shahverdiev and K.A. Shore
- Source: IET Optoelectronics, Volume 3, Issue 6, p. 326 –330
- DOI: 10.1049/iet-opt.2009.0028
- Type: Article
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By studying the autocorrelation function of the opto-electronic feedback semiconductor laser output the authors establish that the signatures of time delays can be erased in systems incorporating modulated feedback time delays. This property is of importance for the suitability of such laser systems for secure chaos-based communication systems. The authors also make the first report on chaos synchronisation in both uni-directionally and bi-directionally coupled multiple time-delay chaotic semiconductor lasers with modulated opto-electronic feedbacks.
Editorial: Selected papers inspired by the Semiconductor and Integrated Optoelectronics (SIOE 2009) Conference
Tuning of the critical feedback level in 1.55-μm quantum dash semiconductor laser diodes
Molecular beam epitaxial (MBE) growth and spectroscopy of dilute nitride InAsN:Sb for mid-infrared applications
Low-resistive sulphur-treated ohmic contacts to n-type InAsSb
Coupling characteristics of a soft glass nematic liquid crystal photonic crystal fibre coupler
Generalised synchronisation in laser devices with electro-optical feedback
Design and characteristics of staggered InGaN quantum-well light-emitting diodes in the green spectral regime
Simulation of dilute nitride GaInNAs doping superlattice solar cells
Effects of carrier escape and capture processes on quantum well solar cells: a theoretical investigation
Gain peak–cavity mode alignment optimisation in buried tunnel junction mid-infrared GaSb vertical cavity surface emitting lasers using hydrostatic pressure
New non-linear analytical model for distortion analysis of vertical cavity surface emitting lasers
Room temperature 633 nm tapered diode lasers with external wavelength stabilisation
Erasure of time-delay signatures in the output of an opto-electronic feedback laser with modulated delays and chaos synchronisation
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