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Sökning: swepub > Larsson Anders > Haglund Åsa 1976 > (2011)

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1.
  • Adolfsson, Göran, 1981, et al. (författare)
  • Realization of spectrally engineered semiconductor Fabry-Perot lasers with narrow geometrical tolerances
  • 2011
  • Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 109:9, s. 093112-
  • Tidskriftsartikel (refereegranskat)abstract
    • Spectrally engineered semiconductor Fabry-Perot laser resonators are designed to enhance the optical feedback for selected longitudinal modes, which thereby require less gain for lasing. This is achieved by introducing refractive index perturbations along the length of the resonator. However,the physical realization of these resonators is a challenge because of very narrow tolerances; in particular the need for precise positioning of the end facets of the resonator in relation to the perturbations, and the excess propagation loss associated with the perturbations, has been a majorconcern. We report on a method to achieve high-quality end facet mirrors enabling precise positioning relative to the perturbations, the latter which are realized as lateral corrugations of the waveguide. Measurements show that the mirror quality is comparable to that of cleaved mirrorsand that the additional loss introduced by the perturbations adds
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2.
  • Baveja, P. P., et al. (författare)
  • Assessment of VCSEL thermal rollover mechanisms from measurements and empirical modeling
  • 2011
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:16, s. 15490-15505
  • Tidskriftsartikel (refereegranskat)abstract
    • We use an empirical model together with experimental measurements for studying mechanisms contributing to thermal rollover in vertical-cavity surface-emitting lasers (VCSELs). The model is based on extraction of the temperature dependence of threshold current, internal quantum efficiency, internal optical loss, series resistance and thermal impedance from measurements of output power, voltage and lasing wavelength as a function of bias current over an ambient temperature range of 15-100 degrees C. We apply the model to an oxide-confined, 850-nm VCSEL, fabricated with a 9-mu m inner-aperture diameter and optimized for highspeed operation, and show for this specific device that power dissipation due to linear power dissipation (sum total of optical absorption, carrier thermalization, carrier leakage and spontaneous carrier recombination) exceeds power dissipation across the series resistance (quadratic power dissipation) at any ambient temperature and bias current. We further show that the dominant contributors to self-heating for this particular VCSEL are quadratic power dissipation, internal optical loss, and carrier leakage. A rapid reduction of the internal quantum efficiency at high bias currents (resulting in high temperatures) is identified as being the major cause of thermal rollover. Our method is applicable to any VCSEL and is useful for identifying the mechanisms limiting the thermal performance of the device and to formulate design strategies to ameliorate them.
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3.
  • Gierl, Christian, et al. (författare)
  • Tuneable VCSEL aiming for the application in interconnects and short haul systems
  • 2011
  • Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819484963 ; 7959
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Widely tunable vertical cavity surface emitting lasers (VCSEL) are of high interest for optical communications, gas spectroscopy and fiber-Bragg-grating measurements. In this paper we present tunable VCSEL operating at wavelength around 850 nm and 1550 nm with tuning ranges up to 20 nm and 76 nm respectively. The first versions of VCSEL operating at 1550 nm with 76 nm tuning range and an output power of 1.3mW were not designed for high speed modulation, but for applications where only stable continious tuning is essential (e.g. gas sensing). The next step was the design of non tunable VCSEL showing high speed modulation frequencies of 10 GHz with side mode supression ratios beyond 50 dB. The latest version of these devices show record output powers of 6.7mW at 20 °C and 3mW at 80 °C. The emphasis of our present and future work lies on the combination of both technologies. The tunable VCSEL operating in the 850 nm-region reaches a modulation bandwidth of 5.5GHz with an output power of 0.8mW.
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4.
  • Haglund, Erik, 1985, et al. (författare)
  • Low Spectral Width High-Speed VCSELs
  • 2011
  • Ingår i: International Nano-Optoelectronic Workshop (iNOW).
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The transmission distance of high-speed multimode 850 nm VCSELs is currently limited by modal dispersion. A design and process to fabricate high-speed VCSELs with a reduced spectral width using a surface relief technique are presented.
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5.
  • Ingham, J.D., et al. (författare)
  • 32 Gb/s multilevel modulation of an 850 nm VCSEL for next-generation datacommunication standards
  • 2011
  • Ingår i: 2011 Conference on Lasers and Electro-Optics, CLEO 2011; Baltimore, MD; 1 May 2011 through 6 May 2011. - Washington, D.C. : OSA. - 2162-2701. - 9781557529107
  • Konferensbidrag (refereegranskat)abstract
    • An 850 nm vertical-cavity surface-emitting laser is modulated at 32 Gb/s using pulseamplitude modulation with four levels. Transmitter predistortion generates an optimized modulation waveform, which requires a receiver bandwidth of only 15 GHz.
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6.
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7.
  • Kögel, Benjamin, 1979, et al. (författare)
  • Integrated MEMS-tunable VCSELs with high modulation bandwidth
  • 2011
  • Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 47:13, s. 764-756
  • Tidskriftsartikel (refereegranskat)abstract
    • The modulation bandwidth of micromachined tunable VCSELs is typically limited by the parasitic capacitance associated with the large mesa platform for the movable mirror. Presented is a simple technology for wafer-scale integration of tunable VCSELs with low mesa capacitance and high modulation bandwidth. Small signal measurements show a 3dB bandwidth of up to 6 GHz over a tuning range of 18 nm. Digital modulation is demonstrated with error-free data transmission at 5 Gbit/s and eye diagrams at 10 Gbit/s.
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8.
  • Kögel, Benjamin, 1979, et al. (författare)
  • Singlemode tunable VCSELs with integrated MEMS technology
  • 2011
  • Ingår i: European Conference on Laser and Electro-Optics (CLEO/Europe).
  • Konferensbidrag (refereegranskat)abstract
    • A simple MEMS technology for wafer-scale integration of short-wavelength tunable VCSELs is presented. Using a 3D model the half-symmetric cavity is optimized for singlemode emission from 10 μm large apertures over 12 nm tuning range.
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9.
  • Larsson, Anders, 1957, et al. (författare)
  • High speed VCSELs for short reach communication
  • 2011
  • Ingår i: Semiconductor Science and Technology. - 1361-6641 .- 0268-1242. ; 26:1, s. 014017-1-5-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the design of a high-speed 850 nm multimode vertical cavity surface-emitting laser (VCSEL) and demonstrate record performance in terms of small signal modulation bandwidth (23 GHz) and error-free operation at high bit rates (40 Gb s−1). The large bandwidth was enabled by an active region design for large differential gain and small gain compression, a low reflectivity top mirror for photon lifetime reduction and multiple oxide layers for a reduction of the capacitance. Error-free operation at 40 Gb s−1 was achieved in a back-to-back configuration with less than 0 dBm of received optical power.
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10.
  • Szczerba, Krzysztof, 1985, et al. (författare)
  • 30 Gbps 4-PAM transmission over 200m of MMF using an 850 nm VCSEL
  • 2011
  • Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:26, s. B203-B208
  • Tidskriftsartikel (refereegranskat)abstract
    • We present high speed real time, error free 4-PAMtransmissionfor short range optical links based on a VCSEL operating at 850 nm, a multimode fibre and a simple intensity detector. Transmission speeds of 25 Gbps and 30 Gbps are demonstrated, and the maximum fibre reaches were 300 m and 200 m, respectively. The 4-PAM is also compared with OOK transmission at 25 Gbps, and we find that at this bit rate 4-PAM increases the error free transmission distance in the multimode fibre by 100 m, compared to OOK.
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