| 1. |
- Wang, Shu Min, 1963, et al.
(author)
-
Growth of dilute nitrides and 1.3 μm edge emitting lasers on GaAs by MBE
- 2011
-
In: Physica Status Solidi (B): Basic Research. - : Wiley. - 1521-3951 .- 0370-1972. ; 248:5, s. 1207-1211
-
Journal article (peer-reviewed)abstract
- In this paper, we report recent progresses on growth of dilute nitrides and 1.3 mu m lasers on GaAs using molecular beam epitaxy at Chalmers University of Technology, Sweden. Intense long wavelength light emission up to 1.71 mu m at room temperature has been achieved by using the N irradiation method and the low growth rate. It is also demonstrated that incorporation of N in relaxed InGaAs buffer grown on GaAs strongly enhances the optical quality of metamorphic InGaAs quantum wells. With the optimized growth conditions and the laser structures, we demonstrate 1.3 mu m GaInNAs edge emitting lasers on GaAs with state-of-the-art performances including a low threshold current density, a high-characteristic temperature, a 3 dB bandwidth of 17 GHz and uncooled operation at 10 Gbit/s up to 110 degrees C. The laser performances are comparable with the best reported data from the InGaAsP lasers on InP and is superior to the InAs quantum dot lasers on GaAs.
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| 2. |
- Gustavsson, Johan, 1974, et al.
(author)
-
High speed 850nm VCSELs for >40Gb/s transmission
- 2013
-
In: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013. - 9781479904570 ; , s. OTh4H.4-
-
Conference paper (peer-reviewed)abstract
- VCSELs capable of direct modulation exceeding 40Gb/s are needed in next generation optical interconnect standards. Using a refined high-speed design we demonstrate GaAs-based VCSELs having record-high 28GHz modulation bandwidth, and that operate error-free at 47Gb/s.
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| 3. |
- Gustavsson, Johan, 1974, et al.
(author)
-
High-speed, high-temperature VCSELs for optical interconnects
- 2013
-
In: 2013 IEEE Photonics Society Summer Topical Meeting Series, PSSTMS 2013. - 9781467350600 ; , s. 7-8
-
Conference paper (peer-reviewed)abstract
- Directly modulated VCSELs operating at 40Gb/s are required for next generation optical interconnect standards. Using a refined high-speed design we demonstrate GaAs-based VCSELs that operate error-free at 47Gb/s at 25°C, and 40Gb/s at 85°C.
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| 4. |
- Haglund, Erik, 1985, et al.
(author)
-
850 nm datacom VCSELs for higher-speed and longer-reach transmission
- 2013
-
In: European VCSEL Day 2013.
-
Conference paper (peer-reviewed)abstract
- The 850 nm GaAs-based VCSEL is already the dominating technology for transmitters in optical interconnects up to 100 m in datacenters, thanks to low-cost fabrication, excellent high-speed properties at low currents and the existence of high-speed OM4 multimode fiber optimized for this particular wavelength. Future datacenters will require faster and more energy-efficient VCSELs to increase the overall bandwidth and reduce the power consumption of the datacenter network. In addition, longer-reach interconnects exceeding 1 km will also be required as datacenters grow into large multi-building complexes.By optimizing the doping profiles of the DBRs to reduce resistance, using a short (½-λ) cavity to improve longitudinal optical confinement and optimizing the photon lifetime for optimal damping, we obtained a record-high small-signal modulation bandwidth of 28 GHz for a ~4 µm oxide aperture VCSEL. A 7 µm oxide aperture VCSEL (~27 GHz bandwidth) enabled error-free transmission (bit-error-rate 300 m), the large spectral width of VCSELs leads to severe signal degradation by fiber dispersion. We have investigated two methods of fabricating low-spectral width quasi-single mode VCSELs to mitigate this problem. By using a small oxide aperture of ~3 µm, error-free transmission was achieved at 22 Gbit/s over 1.1 km of OM4 fiber. An alternative approach is to use an integrated mode filter in the form of a shallow surface relief to reduce the spectral width of the VCSEL. The mode filter allows for the use of a larger oxide aperture and thereby enables a lower resistance and operation at a lower current density. A 5 µm oxide aperture VCSEL with a mode filter enabled error-free transmission at 25 Gbit/s over 500 m of OM4 fiber.
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| 5. |
- Haglund, Erik, 1985, et al.
(author)
-
High-speed lasers for optical interconnects
- 2012
-
In: Swedish Optics and Photonics Days 2012.
-
Conference paper (other academic/artistic)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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| 6. |
- Haglund, Erik, 1985, et al.
(author)
-
Quasi-single mode VCSELs for longer-reach multimode fiber optical interconnects
- 2014
-
In: Summers School on Optical Interconnects, 3-6 June 2014, Thessaloniki.
-
Conference paper (other academic/artistic)abstract
- Longer-reach (>300 m) optical interconnects are needed asdatacenters grow ever larger. Today the reach of 850 nmVCSEL-based optical interconnects is mainly limited by fiber dispersion. By reducing the spectral width of the VCSEL, the effects of fiber dispersion may be reduced, effectively increasing the error-free transmission distance.
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| 7. |
- Karppinen, Mikko, et al.
(author)
-
Integration of 150 Gbps/fiber optical engines based on multicore fibers and 6-channel VCSELs and PDs
- 2016
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781628419887 ; 9753, s. Art. no. 97530S-
-
Conference paper (peer-reviewed)abstract
- Multicore fiber enables a parallel optic data link with a single optical fiber, thus providing an attractive way to increase the total throughput and the integration density of the interconnections. We study and present photonics integration technologies and optical coupling approaches for multicore transmitter and receiver subassemblies. Such optical engines are implemented and characterized using multimode 6-core fibers and multicore-optimized active devices: 850-nm VCSEL and PD arrays with circular layout and multi-channel driver and receiver ICs. They are developed for bit-rates of 25 Gbps/channel and beyond, i.e.
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| 8. |
- Larsson, Anders, 1957, et al.
(author)
-
High speed VCSELs for optical interconnects
- 2012
-
In: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - 1092-8669. - 9781467317252 ; , s. 269-272
-
Conference paper (peer-reviewed)abstract
- This paper presents an overview of our recent work on high speed, oxide confined, 850 nm vertical cavity surface emitting lasers (VCSELs). With proper active region and cavity designs, and techniques for reducing capacitance and thermal impedance, we have reached a modulation bandwidth of 23 GHz and demonstrated 40 Gbps transmission. Using an integrated mode filter for reducing the spectral width we have extended the reach on multimode fiber at 25 Gbps from 100 to 500 m. Improved link capacity was also demonstrated using a more spectrally efficient multi-level modulation format (4-PAM). Finally, a MEMS-technology for wafer scale integration of tunable high speed VCSELs was developed, enabling a tuning range of 24 nm, a 6 GHz modulation bandwidth, and 5 Gbps transmission.
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| 9. |
- Safaisini, Rashid, 1981, et al.
(author)
-
20 Gbit/s data transmission over 2 km multimode fibre using 850 nm mode filter VCSEL
- 2014
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 50:1, s. 40-42
-
Journal article (peer-reviewed)abstract
- Error-free data transmission over 1.3 and 2 km multimode fibre at 25 and 20 Gbit/s, respectively, is demonstrated using a high-speed, single-mode, 850 nm vertical-cavity surface-emitting laser (VCSEL) with an integrated mode filter. This result represents a bitrate-distance product of 40 Gbit/s km, a new record for multimode fibre VCSELbased interconnects.
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| 10. |
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| 11. |
- Safaisini, Rashid, 1981, et al.
(author)
-
22 Gb/s error-free data transmission beyond 1 km of multi-mode fiber using 850 nm VCSELs
- 2013
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819494085 ; 8639
-
Conference paper (peer-reviewed)abstract
- The first error-free data transmission beyond 1 km of multi-mode fiber at bit-rates exceeding 20 Gb/s is demonstrated using a high modulation bandwidth, quasi-single mode (SMSR similar to 20 dB) 850 nm VCSEL. A VCSEL with small similar to 3 mu m aperture shows quasi-single mode operation with a narrow spectral width. The top mirror reflectivity of the VCSEL is optimized for high speed and high output power by shallow etching. A combination of narrow spectral width and high optical power reduces the effects of fiber dispersion and fiber and connector losses and enables such a long transmission distance at high bit-rates.
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| 12. |
- Safaisini, Rashid, 1981, et al.
(author)
-
High-Speed 850 nm Quasi-Single Mode VCSELs for Extended Reach Optical Interconnects
- 2013
-
In: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 5:7, s. 686-695
-
Journal article (peer-reviewed)abstract
- This paper presents recent results on high-speed, quasi-single-mode, 850 nm vertical-cavity surface-emitting lasers (VCSELs) with a narrow spectral width for extended-reach optical interconnects. The top mirror reflectivity is adjusted for high output power, slope efficiency, and small signal modulation bandwidth. An oxide confined VCSEL with an ∼3 μm aperture diameter delivers 2 mW of output power and reaches a resonance frequency as high as 25 GHz and a modulation bandwidth exceeding 20 GHz. A small K-factor of 0.17 ns and a large D-factor of 17.3 GHz/mA1/2, extracted from the VCSEL modulation response, along with the improved DC and modal properties enable energy-efficient data transmission at high bit rates over long-distance multimode fiber. Error-free transmission at bit rates exceeding 20 Gbits/s over 1.1 km of OM4 fiber is demonstrated and shown to be limited mainly by the photoreceiver bandwidth. A theoretical investigation of the dependence of link performance on photoreceiver bandwidth is also presented.
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| 13. |
- Stampoulidis, Leontios, et al.
(author)
-
The European project Merlin on multi-gigabit, energy-efficient, ruggedized lightwave engines for advanced on-board digital processors
- 2017
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10563
-
Conference paper (peer-reviewed)abstract
- Modern broadband communication networks rely on satellites to complement the terrestrial telecommunication infrastructure. Satellites accommodate global reach and enable world-wide direct broadcasting by facilitating wide access to the backbone network from remote sites or areas where the installation of ground segment infrastructure is not economically viable. At the same time the new broadband applications increase the bandwidth demands in every part of the network - and satellites are no exception. Modern telecom satellites incorporate On-Board Processors (OBP) having analogue-to-digital (ADC) and digital-to-analogue converters (DAC) at their inputs/outputs and making use of digital processing to handle hundreds of signals; as the amount of information exchanged increases, so do the physical size, mass and power consumption of the interconnects required to transfer massive amounts of data through bulk electric wires.
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| 14. |
- Westbergh, Petter, 1981, et al.
(author)
-
High-speed 850 nm VCSELs operating error free up to 57 Gbit/s
- 2013
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 49:16, s. 1021-1023
-
Journal article (peer-reviewed)abstract
- Error-free transmission is demonstrated at bit rates up to 57 Gbit/s back-to-back, up to 55 Gbit/s over 50 m fibre and up to 43 Gbit/s over 100 m fibre using an oxide-confined 850 nm high-speed vertical cavity surface-emitting laser with a photon lifetime optimised for high-speed data transmission.
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| 15. |
|
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| 16. |
- Westbergh, Petter, 1981, et al.
(author)
-
High-speed 850 nm VCSELs with 28 GHz modulation bandwidth for short reach communication
- 2013
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819494085 ; 8639
-
Conference paper (peer-reviewed)abstract
- We present results from our new generation of high performance 850 nm oxide confined vertical cavity surface-emitting lasers (VCSELs). With devices optimized for high-speed operation under direct modulation, we achieve record high 3dB modulation bandwidths of 28 GHz for similar to 4 mu m oxide aperture diameter VCSELs, and 27 GHz for devices with a similar to 7 mu m oxide aperture diameter. Combined with a high-speed photoreceiver, the similar to 7 mu m VCSEL enables error-free transmission at data rates up to 47 Gbit/s at room temperature, and up to 40 Gbit/s at 85 degrees C.
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| 17. |
- Westbergh, Petter, 1981, et al.
(author)
-
High-speed 850 nm VCSELs with 28 GHz modulation bandwidth operating error-free up to 44 Gbit/s
- 2012
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:18, s. 1145-U178
-
Journal article (peer-reviewed)abstract
- A new generation of high-speed oxide confined 850 nm vertical cavity surface-emitting lasers is presented. A record high modulation bandwidth of 28 GHz is achieved and error-free data transmission at bit-rates up to 44 Gbit/s is demonstrated.
|
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| 18. |
- Westbergh, Petter, 1981, et al.
(author)
-
High-Speed Oxide Confined 850-nm VCSELs Operating Error-Free at 40 Gb/s up to 85 degrees C
- 2013
-
In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 25:8, s. 768-771
-
Journal article (peer-reviewed)abstract
- We present the temperature dependence of the performance characteristics of our latest generation high-speed oxide confined 850-nm vertical cavity surface-emitting lasers (VCSELs). Using a 7-mu m oxide aperture diameter VCSEL, we demonstrate a maximum modulation bandwidth of similar to 27 GHz at room temperature and similar to 21 GHz at 85 degrees C. With a new highspeed optical receiver, these bandwidths enable error-free data transmission ( defined as a bit-error-rate
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| 19. |
- Westbergh, Petter, 1981, et al.
(author)
-
HIgh speed oxide confined 850 nm VCSELs operating error-free at 47 Gbit/s at room temperature and 40 Gbit/s at 85C
- 2013
-
In: Optics InfoBase Conference Papers. - 2162-2701. ; , s. Art. no. 6800720-
-
Conference paper (peer-reviewed)abstract
- Optical links based on multimode fiber and 850 nm VCSELs are critical elements in high performance computing systems, datacenters, and other short reach datacom networks. These applications are driving the demand for high bandwidth and it is anticipated that serial bit-rates up to 40 Gbit/s will be required for the next generation standards. For minimized power consumption, footprint, and cost, these high-speed links must function without active temperature control or cooling, and are consequently required to operate error-free (defined as a BER
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| 20. |
- Bamiedakis, Nikos, et al.
(author)
-
25 Gb/s data transmission over a 1.4 m long multimode polymer spiral waveguide
- 2014
-
In: Conference on Lasers and Electro-Optics Europe - Technical Digest. - Washington, D.C. : OSA. - 9781557529992
-
Conference paper (peer-reviewed)abstract
- Data transmission studies of a 1.4m long multimode polymer spiral waveguide using an 850nm VCSEL are presented. Error-free 25 Gb/s data transmission is demonstrated over that waveguide length, achieving a record bandwidth-length product of 21GHz×m.
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| 21. |
- Bamiedakis, N., et al.
(author)
-
40 Gb/s data transmission over a 1 m long multimode polymer spiral waveguide
- 2014
-
In: European Conference on Optical Communication, ECOC 2014; Cannes; France; 21 September 2014 through 25 September 2014. - 9782954944401 ; , s. Paper P.4.7-
-
Conference paper (peer-reviewed)abstract
- We report record error-free data transmission of 40Gb/s over a 1m-long multimode polymer spiral waveguide. The waveguide imposes no significant transmission impairments in the link despite its highly-multimoded nature and long length, demonstrating its potential in high-speed board-level optical interconnections.
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| 22. |
- Bamiedakis, N., et al.
(author)
-
40 Gb/s Data Transmission Over a 1-m-Long Multimode Polymer Spiral Waveguide for Board-Level Optical Interconnects
- 2015
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 33:4, s. 882-888
-
Journal article (peer-reviewed)abstract
- Optical interconnects have attracted considerable attention for use in short-reach communication links within high-performance electronic systems, such as data centers, supercomputers, and data storage systems. Multimode polymer waveguides, in particular, constitute an attractive technology for use in board-level interconnects as they can be cost-effectively integrated onto standard PCBs and allow system assembly with relaxed alignment tolerances. However, their highly multimoded nature raises important concerns about their bandwidth limitations and their potential to support very high on-board data rates. In this paper, we report record error-free (BER
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| 23. |
- Bamiedakis, N., et al.
(author)
-
56 Gb/s PAM-4 data transmission over a 1 m long multimode polymer interconnect
- 2015
-
In: CLEO: Science and Innovations, CLEO-SI 2015, San Jose; United States; 10-15 May 2015. - 9781557529688 ; , s. 2267-
-
Conference paper (peer-reviewed)abstract
- Advanced modulation formats can enable >40 Gb/s data rates in waveguide-based optical interconnects without the need for high-specification optoelectronic components. Record 56Gb/s PAM-4 data transmission is demonstrated over a 1 m-long multimode polymer waveguide.
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| 24. |
- Baveja, Prashant, 1985, et al.
(author)
-
Impact of device parameters on thermal performance of high speed oxide confined 850 nm VCSELs
- 2012
-
In: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 48:1, s. 17-26
-
Journal article (peer-reviewed)abstract
- We study the impact of device parameters, such asinner-aperture diameter and cavity photon lifetime, on thermal rollover mechanisms in 850-nm, oxide-confined, vertical-cavity surface-emitting lasers (VCSELs) designed for high-speed operation. We perform measurements on four different VCSELs of different designs and use our empirical thermal model for calculating the power dissipated with increasing bias currents through various physical processes such as absorption within the cavity, carrier thermalization, carrier leakage, spontaneous carrier recombination, and Joule heating. When reducing the topmirror reflectivity to reduce internal optical absorption loss we find an increase of power dissipation due to carrier leakage. There is therefore a trade-ff between the powers dissipated owing to optical absorption and carrier leakage in the sense that overcompensating for optical absorption enhances carrier leakage (and vice versa). We further find that carrier leakage places the ultimate limit on the thermal performance for this entire class ofdevices. Our analysis yields useful design optimization strategies for mitigating the impact of carrier leakage and should thereby prove useful for the performance enhancement of 850-nm, highspeed, oxide-confined VCSELs.
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| 25. |
- Baveja, P. P., et al.
(author)
-
Assessment of VCSEL thermal rollover mechanisms from measurements and empirical modeling
- 2011
-
In: Optics Express. - 1094-4087 .- 1094-4087. ; 19:16, s. 15490-15505
-
Journal article (peer-reviewed)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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| 26. |
- Baveja, P. P., et al.
(author)
-
Impact of photon lifetime on thermal rollover in 850-nm high-speed VCSELs
- 2012
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276
-
Conference paper (peer-reviewed)abstract
- We present an empirical thermal model for VCSELs based on extraction of temperature dependence of macroscopic VCSEL parameters from CW measurements. We apply our model to two, oxide-confined, 850-nm VCSELs, fabricated with a 9-mu m inner-aperture diameter and optimized for high-speed operation. We demonstrate that for both these devices, the power dissipation due to linear heat sources dominates the total self-heating. We further show that reducing photon lifetime down to 2 ps drastically reduces absorption heating and improves device static performance by delaying the onset of thermal rollover. The new thermal model can identify the mechanisms limiting the thermal performance and help in formulating the design strategies to ameliorate them.
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| 27. |
- Castro, Jose Manuel, et al.
(author)
-
48.7 Gb/s 4-PAM Transmission over 200 m of High Bandwidth MMF using an 850 nm VCSEL
- 2015
-
In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 27:17, s. 1799-1801
-
Journal article (peer-reviewed)abstract
- We demonstrate 4-PAM 48.67 Gb/s transmission, using a directly modulated VCSEL, over 50, 100 and 200 m of multimode fiber with partial dispersion compensation properties. The results of our experiments indicate that 200 m reach is achievable with forward error correcting codes with small overhead.
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| 28. |
- Castro, Jose Manuel, et al.
(author)
-
50 Gb/s 4-PAM over 200 m of High Bandwidth MMF using a 850 nm VCSEL
- 2015
-
In: Optical Fiber Communication Conference 2015, Los Angeles, California, United States, 22–26 March 2015. - 9781557529374
-
Conference paper (peer-reviewed)abstract
- Experiments for transmission of 50Gb/s, 4-PAM using direct modulated VCSEL over 100m and 200m of MMF with partial dispersion compensation properties are presented.
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| 29. |
- Castro, J. M., et al.
(author)
-
Investigation of 60 Gb/s 4-PAM Using an 850 nm VCSEL and Multimode Fiber
- 2016
-
In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 34:16, s. 3825-3836
-
Journal article (peer-reviewed)abstract
- We investigate 4-pulse-amplitude modulation (PAM) at data rates in the range of 50-60 Gb/s using a directly modulated 850 nm VCSEL and multimode fiber links up to 200 m. The channel conditions in which 4-PAM has performance advantages over traditional ON-OFF keying are evaluated followed by experimental results at data rates of 56.7 Gb/s over distances up to 200 m using equalization and FEC, with a post-FEC bit error rate of 10(-12). The reported analysis is applicable to future Ethernet and Fibre Channel applications requiring 50 Gb/s serial data rates per lane over multimode fibers.
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| 30. |
- Chen, Jingjing, 1982, et al.
(author)
-
An Energy Efficient 56 Gbps PAM-4 VCSEL Transmitter Enabled by a 100 Gbps Driver in 0.25 µm InP DHBT Technology
- 2016
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 34:21, s. 954-4964
-
Journal article (peer-reviewed)abstract
- Datacenters demand higher speed VCSEL-based optical interconnects at low power consumption. As a potential technology enabler, this paper presents a wide bandwidth and energy efficient multilevel PAM VCSEL driver implemented in an InP 0.25 μm double heterojunction bipolar transistor (DHBT) technology. The operational bandwidth of the driver is verified and error-free electrical data transmission up to 56 Gbps PAM-2 and 100 Gbps PAM-4 is demonstrated at a driver energy consumption less than 2 pJ/bit. The driver is integrated and tested with an in-house fabricated 850 nm VCSEL. Error-free 56 Gbps PAM-4 optical transmission at a transmitter energy consumption of 3.7 pJ/bit is demonstrated without equalization. This is the highest data rate reported for an integrated PAM-4 modulated VCSEL transmitter, while being the most energy efficient above 40 Gbps operation. Moreover, the VCSEL driver offers a pre-emphasis feature at PAM-2 operation for improved link throughput and receiver sensitivity.
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| 31. |
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| 32. |
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| 33. |
- Davani, Hooman A., et al.
(author)
-
Polarization investigation of a tunable high-speed short-wavelength bulk-micromachined MEMS-VCSEL
- 2012
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Art. no. 82760T-
-
Conference paper (peer-reviewed)abstract
- We report the investigation of the state of polarization (SOP) of a tunable vertical-cavity surface-emitting laser (VCSEL) operating near 850 nm with a mode-hop free single-mode tuning range of about 12 nm and an amplitude modulation bandwidth of about 5 GHz. In addition, the effect of a sub-wavelength grating on the device and its influence on the polarization stability and polarization switching has been investigated. The VCSEL with an integrated sub-wavelength grating shows a stable SOP with a polarization mode suppression ratio (PMSR) more than 35 dB during the tuning.
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| 34. |
- Davani, Hooman A., et al.
(author)
-
Widely Electro Thermal Tunable Bulk-Micromachined MEMS-VCSEL Operating Around 850nm
- 2011
-
In: Conference on Lasers and Electro-Optics/Pacific Rim, CLEOPR 2011; Sydney; Australia; 28 August 2011 through 1 September 2011. - 2162-2701. - 9780977565771 ; , s. 32-34
-
Conference paper (peer-reviewed)abstract
- We present the highest reported continues tuning range of 37 nm and fastest electro thermal tuning speed of 700 Hz achieved with tunable vertical-cavity surface-emitting lasers (VCSEL) and semiconductor DBRs at 850 nm wavelength range.
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| 35. |
- Davani, Hooman A., et al.
(author)
-
Widely tunable high-speed bulk-micromachined short-wavelength MEMS-VCSEL
- 2010
-
In: Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International. - 0899-9406. - 9781424456833 ; , s. 9-10
-
Conference paper (peer-reviewed)abstract
- We present the first results of a high-speed bulk-micromachined tunable vertical-cavity surface-emitting laser (VCSEL) operating near 850nm using a half-symmetric resonator with a movable curved microelectromechanical system (MEMS) membrane.
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| 36. |
- Gierl, Christian, et al.
(author)
-
Tuneable VCSEL aiming for the application in interconnects and short haul systems
- 2011
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819484963 ; 7959
-
Conference paper (other academic/artistic)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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| 37. |
- Gustavsson, Johan, 1974, et al.
(author)
-
High-speed 850-nm VCSELs for 40 Gb/s transmission
- 2010
-
Conference paper (other academic/artistic)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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| 38. |
- Gustavsson, Johan, 1974, et al.
(author)
-
Optimized active region design for high speed 850 nm VCSELs
- 2009
-
In: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference; Munich; Germany; 14 June 2009 through 19 June 2009. - 9781424440801 ; , s. Art. no. 5192928-
-
Conference paper (peer-reviewed)abstract
- Short wavelength (850 nm) VCSELs operating at speeds of 25 Gb/s and above are needed for future highcapacity, short reach data communication links. The modulation bandwidth is intrinsically limited by thedifferential gain of the QWs used in the active region of the VCSEL. In this work we explore the use of strainedInGaAs/AlGaAs QWs and benchmark the performance against conventional GaAs/AlGaAs QWs.An 8-band k⋅p model [1] was used to calculate the energy band dispersions, using band offsets from modelsolid theory [2]. In all cases, the QW and barrier compositions and QW thickness were chosen for a gain peak at845 nm, enabling emission at 850 nm with a small detuning between the gain peak and the cavity resonance.With increasing In-concentration the QW thickness is reduced and the Al-concentration in the barrier isincreased to maintain the gain peak at 845 nm and the number of QWs is increased to maintain opticalconfinement and enable operation at a low carrier density for high differential gain. It was found that theincorporation of up to 10% In leads to a significant reduction in threshold carrier density and increase indifferential gain. This is due to an increased separation and reduced mixing between the highest heavy-hole andlight-hole valence bands (Fig.1). A further increase of In concentration leads to a less marked improvement.With an optimum active region design (5 x 4 nm In0.10Ga0.90As/Al0.37Ga0.63As QWs) a differential gain twice ashigh as that of a conventional design with 3 x 8 nm GaAs/Al0.30Ga0.70As QWs was predicted (Table 1).The improvement of differential gain was experimentally confirmed by extracting the resonance frequencyand its dependence on current from the modulation response of VCSELs with optimized InGaAs/AlGaAs QWand conventional GaAs/AlGaAs QW active regions. The differential gain was calculated from the correspondingD-factors (Fig.2) [3]. Excellent agreement was obtained between theory and experiments (Table 1).VCSELs with an optimized InGaAs/AlGaAs QW active region have a modulation bandwidth of 20 GHz at25° and 15 GHz at 85°C [4] and have enabled error-free transmission over 50 (100) m multimode fiber up to 32(25) Gb/s at a bias current density as low as 11 kA/cm2 under direct current modulation.
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| 39. |
- Haglund, Emanuel, 1988, et al.
(author)
-
20-Gb/s Modulation of Silicon-Integrated Short-Wavelength Hybrid-Cavity VCSELs
- 2016
-
In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 28:8, s. 856 - 859
-
Journal article (peer-reviewed)abstract
- We investigate the dynamics of silicon-integrated 850-nm-wavelength hybrid-cavity vertical-cavity surface-emitting lasers (VCSELs). The VCSELs consist of a GaAs-based half-VCSEL attached to a dielectric distributed Bragg reflector on a silicon substrate using ultra-thin divinylsiloxane-bis-benzocyclobutene adhesive bonding. A 5-µm oxide aperture diameter VCSEL, with a small signal modulation bandwidth of 11 GHz, supports data transmission at bit rates up to 20 Gb/s. The modulation bandwidth and the large signal modulation characteristics are found to be impaired by the high thermal impedance.
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| 40. |
- Haglund, Erik, 1985, et al.
(author)
-
25 Gbit/s transmission over 500 m multimode fibre using 850 nm VCSEL with integrated mode filter
- 2012
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:9, s. 517-518
-
Journal article (peer-reviewed)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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| 41. |
- Haglund, Erik, 1985, et al.
(author)
-
30 GHz bandwidth 850 nm VCSEL with sub-100 fJ/bit energy dissipation at 25-50 Gbit/s
- 2015
-
In: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 51:14, s. 1096-1097
-
Journal article (peer-reviewed)abstract
- A high-speed and energy-efficient oxide-confined 850 nm vertical-cavity surface-emitting laser (VCSEL) for optical interconnects is presented. A record-high modulation bandwidth of 30 GHz is reached for a 3.5 mu m oxide aperture VCSEL, with 25 GHz bandwidth already at a bias current of 1.8 mA. The high bandwidth at low currents enables energy-efficient transmission with a dissipated heat energy in the VCSEL of
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| 42. |
- Haglund, Emanuel, 1988, et al.
(author)
-
Dynamic properties of silicon-integrated short-wavelength hybrid-cavity VCSEL
- 2016
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781510600010 ; 9766
-
Conference paper (peer-reviewed)abstract
- We present a vertical-cavity surface-emitting laser (VCSEL) where a GaAs-based “half-VCSEL” is attached to a dielectric distributed Bragg reflector on silicon using ultra-thin divinylsiloxane-bis-benzocyclobutene (DVS-BCB) adhesive bonding, creating a hybrid cavity where the optical field extends over both the GaAs- and the Si-based parts of the cavity. A VCSEL with an oxide aperture diameter of 5 μm and a threshold current of 0.4 mA provides 0.6 mW output power at 845 nm. The VCSEL exhibits a modulation bandwidth of 11 GHz and can transmit data up to 20 Gbps.
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| 43. |
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| 44. |
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| 45. |
- Haglund, Erik, 1985, et al.
(author)
-
High-Speed VCSELs with Strong Confinement of Optical Fields and Carriers
- 2016
-
In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 34:2, s. 269-277
-
Journal article (peer-reviewed)abstract
- We present the design, fabrication, and performance of our latest generation high-speed oxide-confined 850-nm verticalcavity surface-emitting lasers. Excellent high-speed properties are obtained by strong confinement of optical fields and carriers. Highspeed modulation is facilitated by using the shortest possible cavity length of one half wavelength and placing oxide apertures close to the active region to efficiently confine charge carriers. The resulting strong current confinement boosts internal quantum efficiency, leading to low threshold currents, high wall-plug efficiency, and state-of-the-art high-speed properties at low bias currents. The temperature dependent static and dynamic performance is analyzed by current-power-voltage and small-signal modulation measurements.
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| 46. |
- Haglund, Emanuel, 1988, et al.
(author)
-
Impact of Damping on High-Speed Large Signal VCSEL Dynamics
- 2015
-
In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 33:4, s. 795 - 801
-
Journal article (peer-reviewed)abstract
- An investigation of the optimal relaxation oscillation damping for high-speed 850-nm vertical-cavity surface-emitting laser (VCSEL) under large signal operation is presented, using devices with K-factors ranging from 0.1 to 0.4 ns. Time-domain measurements of turn-on transients are used to quantify damping dependent rise times, overshoots, and signal amplitudes. Optical eye diagrams together with timing jitter and bit error rate measurements reveal a tradeoff between the rise time and the duration of the relaxation oscillations. To produce a high-quality eye at a specific data rate, a proper amount of damping is needed to simultaneously obtain sufficiently high bandwidth and low timing jitter. We found that for error-free transmission, a VCSEL with a 0.3 ns K-factor achieved the best receiver sensitivity at 10 and 25 Gb/s, whereas a less damped VCSEL with a 0.2 ns K-factor achieved the best sensitivity at 40 Gb/s.
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| 47. |
- Haglund, Emanuel, 1988, et al.
(author)
-
Impact of Damping on Large Signal VCSEL Dynamics
- 2014
-
In: Conference Digest - IEEE International Semiconductor Laser Conference. - 0899-9406. - 9781479957217 ; , s. 78-79
-
Conference paper (peer-reviewed)abstract
- The dependence of large signal VCSEL dynamics on damping is studied through time-domain measurements of turn-on transients and timing jitter for VCSELs having K-factors from 0.1 to 0.4 ns.
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| 48. |
- Haglund, Erik, 1985, et al.
(author)
-
Low Spectral Width High-Speed VCSELs
- 2011
-
In: International Nano-Optoelectronic Workshop (iNOW).
-
Conference paper (other academic/artistic)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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| 49. |
- Haglund, Erik, 1985, et al.
(author)
-
Mode-filtered semiconductor lasers enable longer-reach optical interconnects
- 2012
-
In: SPIE Newsroom. - : SPIE-Intl Soc Optical Eng. - 1818-2259.
-
Journal article (other academic/artistic)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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| 50. |
- Haglund, Emanuel, 1988, et al.
(author)
-
Optimum Damping Level for High-Speed Large Signal VCSEL modulation
- 2014
-
In: Optics and Photonics in Sweden, 11-12 Nov. 2014.
-
Conference paper (other academic/artistic)abstract
- The commercial optical interconnects used in datacenters and high performance computers have recently been pushed to data rates of 25-28 Gbps. Near future standards will require even higher data rates and further work to increase the speed is therefore necessary. Typically the 850 nm vertical-cavity surface-emitting laser (VCSEL) is employed as light source in such optical interconnects, due to its low-cost fabrication and excellent high-speed properties at low drive currents.Previously, we have shown that a reduction of the damping of the VCSEL small signal modulation response can increase the modulation bandwidth (BW) and that there exists an optimum damping for maximum BW. This allowed us to demonstrate a record-high small signal modulation BW of 28 GHz and error-free [bit error rate (BER)
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