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Träfflista för sökning "WFRF:(Haglund Åsa 1976 ) srt2:(2010)"

Sökning: WFRF:(Haglund Åsa 1976 ) > (2010)

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1.
  • Kögel, Benjamin, 1979, et al. (författare)
  • Integrated Tunable VCSELs With Simple MEMS Technology
  • 2010
  • Ingår i: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833
  • Konferensbidrag (refereegranskat)abstract
    • A simple MEMS technology for wafer-scale fabrication of tunable VCSELs is presented. Reflown photo-resist droplets serve as preform for making curved movable micro-mirrors. First devices show a tuning range of 15 nm with mW-output power.
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2.
  • Gustavsson, Johan, 1974, et al. (författare)
  • High-speed 850-nm VCSELs for 40 Gb/s transmission
  • 2010
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • We have explored the possibility to extend the data transmission rate for standard 850-nm GaAs-based VCSELs beyond the 10 Gbit/s limit of today's commercially available directly-modulated devices. By sophisticated tailoring of the design for high-speed performance we demonstrate that 10 Gb/s is far from the upper limit. For example, the thermal conductivity of the bottom mirror is improved by the use of binary compounds, and the electrical parasitics are kept at a minimum by incorporating a large diameter double layered oxide aperture in the design. We also show that the intrinsic high speed performance is significantly improved by replacing the traditional GaAs QWs with strained InGaAs QWs in the active region. The best overall performance is achieved for a device with a 9 μm diameter oxide aperture, having in a threshold current of 0.6 mA, a maximum output power of 9 mW, a thermal resistance of 1.9 °C/mW, and a differential resistance of 80 Ω. The measured 3dB bandwidth exceeds 20 GHz, and we experimentally demonstrate that the device is capable of error-free transmission (BER
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3.
  • Healy, S. B., et al. (författare)
  • Active Region Design for High-Speed 850-nm VCSELs
  • 2010
  • Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 46:4, s. 506-512
  • Tidskriftsartikel (refereegranskat)abstract
    • Higher speed short-wavelength (850 nm) VCSELs are required for future high-capacity, short-reach data communication links. The modulation bandwidth of such devices is intrinsically limited by the differential gain of the quantum wells (QWs) used in the active region. We present gain calculations using an 8-band k.p Hamiltonian which show that the incorporation of 10% In in an InGaAs/AlGaAs QW structure can approximately double the differential gain compared to a GaAs/AlGaAs QW structure, with little additional improvement achieved by further increasing the In composition in the QW. This improvement is confirmed by extracting the differential gain value from measurements of the modulation response of VCSELs with optimized InGaAs/AlGaAs QW and conventional GaAs/AlGaAs QW active regions. Excellent agreement is obtained between the theoretically and experimentally determined values of the differential gain, confirming the benefits of strained InGaAs QW structures for high-speed 850-nm VCSEL applications.
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4.
  • Kakanakova-Georgieva, Anelia, 1970-, et al. (författare)
  • Mg-doped Al0.85Ga0.15N layers grown by hot-wall MOCVD with low resistivity at room temperature
  • 2010
  • Ingår i: PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS. - : John Wiley and Sons, Ltd. - 1862-6254 .- 1862-6270. ; 4:11, s. 311-313
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the hot-wall MOCVD growth of Mg-doped AlxGa1-xN layers with an Al content as high as x similar to 0.85. After subjecting the layers to post-growth in-situ annealing in nitrogen in the growth reactor, a room temperature resistivity of 7 k Omega cm was obtained indicating an enhanced p-type conductivity compared to published data for AlxGa1-xN layers with a lower Al content of x similar to 0.70 and a room temperature resistivity of about 10 k Omega cm. It is believed that the enhanced p-type conductivity is a result of reduced compensation by native defects through growth conditions enabled by the distinct hot-wall MOCVD system.
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5.
  • Larsson, Anders, 1957, et al. (författare)
  • Advances in VCSELs for Communication and Sensing
  • 2010
  • Ingår i: 22nd IEEE International Semiconductor Laser Conference Digest. - 0899-9406. - 9781424456826 ; , s. 4-5
  • Konferensbidrag (refereegranskat)abstract
    • Recent advances in VCSELs for communication and sensing are reviewed, emphasizing the development of high speed VCSELs for datacom systems and high power single-mode VCSELs for sensing applications requiring high spectral purity and coherence.
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6.
  • Larsson, Anders, 1957, et al. (författare)
  • High speed low current density 850 nm VCSELs
  • 2010
  • Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819480118 ; 7615, s. 761505-1-11-
  • Konferensbidrag (refereegranskat)abstract
    • The design of an oxide confined 850 nm VCSEL has been engineered for high speed operation at low current density. Strained InGaAs/AlGaAs QWs, with a careful choice of In and Al concentrations based on rigorous band structure and gain calculations, were used to increase differential gain and reduce threshold carrier density. Various measures, including multiple oxide layers and a binary compound in the lower distributed Bragg reflector, were implemented for reducing capacitance and thermal impedance. Modulation bandwidths > 20 GHz at 25°C and > 15 GHz at 85°C were obtained. At room temperature, the bandwidth was found to be limited primarily by the still relatively large oxide capacitance, while at 85°C the bandwidth was also limited by the thermal saturation of the resonance frequency. Transmission up to 32 Gb/s (on-off keying) over multimode fiber was successfully demonstrated with the VCSEL biased at a current density of only 11 kA/cm2. In addition, using a more spectrally efficient modulation format (16 QAM sub-carrier multiplexing), transmission at 40 Gb/s over 200 m multimode fiber was demonstrated.
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8.
  • Westbergh, Petter, 1981, et al. (författare)
  • 40 Gbit/s error-free operation of oxide-confined 850 nm VCSEL
  • 2010
  • Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 46:14, s. 1014-1015
  • Tidskriftsartikel (refereegranskat)abstract
    • Error-free transmission is demonstrated at bit rates up to 40 Gbit/s in a back-to-back configuration and up to 35 Gbit/s over 100 m multimode fibre using a directly modulated oxide confined 850 nm vertical cavity surface emitting laser.
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9.
  • Westbergh, Petter, 1981, et al. (författare)
  • 850 nm VCSEL Operating Error-Free at 40 Gbit/s
  • 2010
  • Ingår i: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833 ; , s. 154 - 155
  • Konferensbidrag (refereegranskat)abstract
    • We report on speed enhancement of 850 nm oxide confined VCSELs by photon lifetime reduction and demonstrate a 23 GHz modulation bandwidth and error-free operation at 40 Gbit/s.
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10.
  • Westbergh, Petter, 1981, et al. (författare)
  • Speed enhancement of VCSELs by photon lifetime reduction
  • 2010
  • Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 46:13, s. 938-940
  • Tidskriftsartikel (refereegranskat)abstract
    • The dependence of the performance of high-speed 850 nm vertical cavity surface-emitting lasers (VCSELs) on photon lifetime is investigated. The photon lifetime is controlled by shallow surface etching. It is demonstrated that a reduction of photon lifetime by similar to 50% leads to a significant improvement of efficiency and speed. A record high 3 dB bandwidth of 23 GHz is achieved.
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