| 1. |
- Chacinski, Marek, et al.
(författare)
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Dynamic properties of electrically p-n confined, epitaxially regrown 1.27 μm InGaAs single-mode vertical-cavity surface-emitting lasers
- 2009
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Ingår i: IET optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 3:3, s. 163-167
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic performance including chirp measurements of 1.27 mu m single-mode InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a large gain-cavity offset is presented. The VCSELs are based on a novel p-n confinement structure with selective area epitaxial regrowth. A resonance frequency of 9.11 GHz, a slope efficiency of 0.25 W/A and an alpha-factor of 5.7 were measured. The modulation bandwidth is limited by electrical parasitics. Eye diagrams at 5 Gb/s with 7 dB extinction ratio and Q-factor around 5 were obtained. The results are compared with the performance of oxide-confined VCSELs with similar active layer and negative gain-cavity detuning.
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| 2. |
- Esebamen, Omeime Xerviar, et al.
(författare)
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Gridded Duo-lateral Position Sensitivity Detector with High Linearity to Low Energetic Electrons in Vacuum Environment
- 2014
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 8:6, s. 217-225
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Tidskriftsartikel (refereegranskat)abstract
- Characterizing a position sensitive detector in a vacuum environment without beam position monitoring devices can bechallenging and expensive. With this in mind, we have designed and fabricated a duo-lateral position sensitive detector (PSD) incorporatedwith simple and inexpensive surface features. It was evaluated using scanning electron microscopy. To assist in pinpointing precise positioningas well as acting as path guide during the sweeping of electrons, multiple grids were lithographically patterned on the top layer of the duolateralPSD. By sweeping electrons along two axes of the detector, the position detection error of both axes was determined from the signalsrecorded using a transimpedance amplification circuit. We were able to characterize the linearity over the x- and y-axis of the PSD and theresults show a very high linearity over two-dimensions of the PSD’s active area and that accurate beam monitoring for spectroscopic measurement without additional beam position monitoring devices is possible.
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| 3. |
- Marcks von Würtemberg, Rickard, et al.
(författare)
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Performance optimisation of epitaxially regrown 1.3-μm vertical-cavity surface-emitting lasers
- 2009
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 3:2, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- A number of GaAs-based long-wavelength, vertical-cavity, surface-emitting laser structures with optical and electrical confinement based on selective area epitaxy have been fabricated and evaluated. The influence on output power, threshold current, thermal stability and modal properties from design parameters such as bottom-distributed Bragg reflector (DBR) doping, cavity doping, dielectric top DBR design and carrier confinement barriers is evaluated. More than 7 mW of output power is emitted from multimode devices with a square active region size of 10 mm. Single-mode power from smaller devices is restricted to 1.5 mW because of a non-optimal cavity shape.
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| 4. |
- Westbergh, Petter, 1981, et al.
(författare)
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Noise, distortion and dynamic range of single mode 1.3 µm InGaAs vertical cavity surface emitting lasers for radio-over-fibre links
- 2008
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 2:2, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- The analogue modulation characteristics, including second order harmonic and third order intermodulation distortion, relative intensity noise (RIN) and spurious free dynamic range (SFDR), of single mode, GaAs-based 1.28 μm vertical cavity surface emitting laser (VCSELs) with highly strained InGaAs quantum wells have been investigated. The VCSELs utilise an oxide aperture for current and optical confinement and an inverted surface relief (SR) for suppression of higher order transverse modes. The inverted SR structure also has the advantage of suppressing oxide modes that, otherwise, appear in VCSELs with a large detuning of the cavity resonance with respect to the gain peak, which is needed to extend the emission wavelength. RIN levels comparable with those of single mode VCSELs emitting at 850 nm are demonstrated, with values from 140 to 150 dB/Hz in the 2 5 GHz range. SFDR values of 100 and 95 dBHz2/3 are obtained at 2 and 5 GHz, respectively. These values are in the range of those required in radio-over-fibre links.
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| 5. |
- Zhu, Z., et al.
(författare)
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Performance of a single-input multiple-output decision feedback equaliser for polarisation mode dispersion compensation
- 2007
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768 .- 1751-8776. ; 1:5, s. 233-240
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Tidskriftsartikel (refereegranskat)abstract
- To compensate the performance degradation induced by polarisation mode dispersion (PMD) in high-speed optical transmission, a single-input multiple-output (SIMO) decision feedback equaliser (DFE) technique is proposed to combat all orders of PMD-induced distortion. The scheme is based on a new SIMO PMD channel model which utilises information embedded in both polarisation states. The performance analysis of the proposed PMD SIMO DFE scheme is provided along with explicit expressions for the filter coefficients. The analysis results show that the new scheme provides a significant improvement over using a first-order optical compensator and conventional DFE.
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| 6. |
- Berglind, Eilert, et al.
(författare)
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Plasmonic/metallic passive waveguides and waveguide components for photonic dense integrated circuits : a feasibility study based on microwave engineering
- 2010
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768. ; 4:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the potential for dense integration of photonic components, we analyse passive plasmonic/metallic waveguides and waveguide components at optical frequencies by using mostly microwave engineering approaches. Four figures of performance are formulated that are utilised to compare the characteristics of four different slab waveguides with zero frequency cut-off modes. Three of these are metallic based whereas the fourth one, which also serves as a reference, is dielectric based with high index-contrast. It is found that all figures of performance cannot be optimised independently; in particular there is a trade-off between the waveguide Q-value and the transversal field confinement. Microwave methods are used to design several photonic transmission line components. The small Q-value of the metallic waveguides is the main disadvantage when using materials and telecom frequencies of today. Hence plasmonic waveguides do not offer full functionality for some important integrated components, being severe for frequency-selective applications. To achieve a dense integration, it is concluded that new materials are needed that offer Q-values several orders of magnitude higher than metals.
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| 7. |
- Alexanderson, Helena, et al.
(författare)
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Coastal glaciers advanced onto Jameson Land, East Greenland during the late glacial-early Holocene Milne Land Stade
- 2014
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 33
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Tidskriftsartikel (refereegranskat)abstract
- We report on Be-10 and optically stimulated luminescence ages from moraines and glaciolacustrine sediments on eastern Jameson Land, East Greenland. Sampled landforms and sediment are associated with advances of outlet glaciers from the local Liverpool Land ice cap situated in the coastal Scoresby Sund region. Previous studies have tentatively correlated these advances with the Milne Land Stade moraines, which are prominent moraine sets deposited by mountain glaciers in the inner Scoresby Sund region. Recent constraints on the formation of the outer and inner of these moraines have suggested two advances of local glaciers, one prior to or during the Younger Dryas and another during the Preboreal. In this paper, we test the correlation of the Liverpool Land glacial advance with the Milne Land Stade. Our results show that outlet glaciers from the Liverpool Land ice cap reached ice-marginal positions marked by moraines in east-facing valleys on Jameson Land sometime during late glacial-early Holocene time (ca. 13-11 Kya). This confirms the correlation of these moraines with the Milne Land Stade moraines described elsewhere in the Scoresby Sund region.
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