| 1. |
- Haglund, Erik, 1985, et al.
(författare)
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25 Gbit/s transmission over 500 m multimode fibre using 850 nm VCSEL with integrated mode filter
- 2012
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:9, s. 517-518
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Tidskriftsartikel (refereegranskat)abstract
- An integrated mode filter in the form of a shallow surface relief was used to reduce the spectral width of a high-speed 850 nm vertical-cavity surface-emitting laser (VCSEL). The mode filter reduced the RMS spectral width from 0.9 to 0.3 nm for a VCSEL with an oxide aperture as large as 5 mu m. Because of reduced effects of chromatic and modal fibre dispersion, the mode filter significantly increases the maximum error-free (bit error rate
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| 2. |
- Haglund, Erik, 1985, et al.
(författare)
-
High-speed lasers for optical interconnects
- 2012
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Ingår i: Swedish Optics and Photonics Days 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the era of cloud computing, with services such as video streaming, social networking, and online storage and file sharing, the demand for online data processing and storage capacity is growing rapidly. These services are hosted in huge data centers that need not only fast servers but also fast communication between servers. Because copper cables have high attenuation at high frequencies, the most promising solution is to use fiber optical links (called optical interconnects) to connect different parts of the data center. Today, gallium arsenide-based vertical-cavity surface-emitting lasers (VCSELs) emitting at 850 nm are the standard light source in transmitters used in commercially available optical interconnects, operating at up to 14 Gbit/s with a link length of up to 300 m. These lasers have the advantages of low power consumption, fast direct modulation at low currents, and low-cost manufacturing. To keep up with the demand of increasing optical interconnect capacity, the Photonics Laboratory at Chalmers university of Technology is conducting research into improving the speed, reach and capacity of VCSELs for optical interconnects.
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| 3. |
- Haglund, Erik, 1985, et al.
(författare)
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Low Spectral Width High-Speed VCSELs
- 2011
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Ingår i: International Nano-Optoelectronic Workshop (iNOW).
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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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| 4. |
- Haglund, Erik, 1985, et al.
(författare)
-
Mode-filtered semiconductor lasers enable longer-reach optical interconnects
- 2012
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Ingår i: SPIE Newsroom. - : SPIE-Intl Soc Optical Eng. - 1818-2259.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- An integrated mode filter significantly decreases the spectral width of conventional short-wavelength vertical-cavity surface-emitting lasers, promising longer optical interconnects for future data centers.
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| 5. |
- Haglund, Erik, 1985, et al.
(författare)
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Reducing the spectral width of high speed oxide confined VCSELs using an integrated mode filter
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Article Number: 82760L-
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Konferensbidrag (refereegranskat)abstract
- We have reduced the spectral width of high speed oxide confined 850 nm VCSELs using a shallow surface relief for suppression of higher order transverse modes. The surface relief acts as a mode filter by introducing a spatially varying and therefore mode selective loss. The VCSEL employs multiple oxide layers for reduced capacitance which leads to a strong index guiding and a large spectral width in the absence of a mode filter. With an appropriate choice of surface relief parameters, the RMS spectral width for a 5 jam oxide aperture VCSEL is reduced from 0.6 to 0.3 nm. The small signal modulation bandwidth is 19 GHz. Due to reduced effects of chromatic and modal fiber dispersion, the maximum error-free (bit-error-rate
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| 6. |
- Kögel, Benjamin, 1979, et al.
(författare)
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Integrated MEMS-tunable VCSELs for reconfigurable optical interconnects
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Article Number: 82760Q-
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Konferensbidrag (refereegranskat)abstract
- A simple and low-cost technology for tunable vertical-cavity surface-emitting lasers (VCSELs) with curved movable micromirror is presented. The micro-electro-mechanical system (MEMS) is integrated with the active optical component (so-called half-VCSEL) by means of surface-micromachining, using a reflown photoresist droplet as sacrificial layer. The technology is demonstrated for electrically pumped, short-wavelength (850nm) tunable VCSEts. Fabricated devices with 10 mu m oxide aperture are singlemode with sidemode suppression >35 dB, tunable over 24 mit with output power up to 0.5 mW, and have a beam divergence angle
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| 7. |
- Kögel, Benjamin, 1979, et al.
(författare)
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Integrated MEMS-Tunable VCSELs Using a Self-Aligned Reflow Process
- 2012
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 48:2, s. 144-152
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Tidskriftsartikel (refereegranskat)abstract
- A simple microelectromechanical systems technology for wafer-scale integration of tunable vertical-cavity surface-emitting lasers (VCSELs) is presented. The key element is a self-aligned reflow process to form photoresist droplets, which serve as sacrificial layer and preform for a curved micromirror. Using a 3-D electromagnetic model, the half-symmetric cavity is optimized for singlemode emission. The technology is demonstrated for electrically pumped, short-wavelength (850 nm) tunable VCSELs, but is transferable to other wavelengths and material systems. Fabricated devices with 10 mu m large current aperture are singlemode and tunable over 24 nm. An improved high-speed design with reduced parasitic capacitance enables direct modulation with 3dB-bandwidths up to 6 GHz and data transmission at 5Gbit/s. Small signal analysis shows that the intrinsic parameters (resonance frequency and damping) are wavelength dependent through the differential gain.
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| 8. |
- Kögel, Benjamin, 1979, et al.
(författare)
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Integrated Tunable VCSELs With Simple MEMS Technology
- 2010
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Ingår i: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833
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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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| 9. |
- Kögel, Benjamin, 1979, et al.
(författare)
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Singlemode tunable VCSELs with integrated MEMS technology
- 2011
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Ingår i: European Conference on Laser and Electro-Optics (CLEO/Europe).
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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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| 10. |
- Larsson, Anders, 1957, et al.
(författare)
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High-speed tunable and fixed-wavelength VCSELs for short-reach optical links and interconnects
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Article Number: 82760H-
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Konferensbidrag (refereegranskat)abstract
- This paper presents a review of recent work on high speed tunable and fixed wavelength vertical cavity surface emitting lasers (VCSELs) at Chalmers University of Technology. All VCSELs are GaAs-based, employ an oxide aperture for current and/or optical confinement, and emit around 850 nm. With proper active region and cavity designs, and techniques for reducing capacitance and thermal impedance, our fixed wavelength VCSELs have reached a modulation bandwidth of 23 GHz, which has enabled error-free 40 Gbps back-to-back transmission and 35 Gbps transmission over 100 m of multimode fiber. A MEMS-technology for wafer scale integration of tunable high speed VCSELs has also been developed. A tuning range of 24 nm and a modulation bandwidth of 6 GHz have been achieved, enabling error-free back-to-back transmission at 5 Gbps.
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