| 1. |
- Bickham, S., et al.
(författare)
-
Low cutoff G.657-compatible fiber for data center interconnects operating in the 1064 and 1310 nm windows
- 2020
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11286
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Konferensbidrag (refereegranskat)abstract
- Optical interconnects in data centers have traditionally used 850 nm GaAs-based vertical-cavity surface-emitting lasers (VCSELs) in combination with multimode fiber, having a reach up to 100 m in length. Longer links typically use standard single-mode fiber in conjunction with either InP-based edge-emitting lasers or silicon photonic transmitters operating in the 1310 nm or 1550 nm window. Single-mode GaAs-based VCSELs operating at 1064 nm offer another path for achieving longer system reach. Potential advantages of these VCSELs include better power efficiency, modulation speeds reaching 50 Gbps and large-scale fabrication volumes. The longer wavelength is also beneficial due to the lower attenuation and chromatic dispersion of optical fibers at that wavelength. However, one practical issue for single-mode transmission is that the G.657 standard for single-mode fiber requires that the 22-meter cable cutoff wavelength be less than 1260 nm, and these fibers are typically few-moded at 1064 nm. The large differences between the group velocities of the LP01 and LP11 modes can lead to degradation of the system performance due to multi-path interference if the higher order modes are present. To resolve this quandary, we have designed and validated the performance of a new optical fiber which is single-moded at wavelengths less than 1064 nm, but also has G.657-compliant mode field diameter and dispersion characteristics that enable it to be used in the 1310 nm window.
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| 2. |
- Larsson, Anders, 1957, et al.
(författare)
-
1060 nm VCSELs for long-reach optical interconnects
- 2018
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Ingår i: Optical Fiber Technology. - : Elsevier BV. - 1095-9912 .- 1068-5200. ; 44, s. 36-42
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Tidskriftsartikel (refereegranskat)abstract
- Reach extension of high capacity optical interconnects based on vertical-cavity surface-emitting lasers (VCSELs) and multimode fibers (MMFs), as needed for large-scale data centers, would benefit from high-speed GaAs-based VCSELs at 1060 nm. At this wavelength, the chromatic dispersion and attenuation of the optical fiber are much reduced in comparison with 850 nm. We present single and multimode 1060 nm VCSELs based on designs derived partly from our high-speed 850 nm VCSEL designs. The single-mode VCSEL, with a modulation bandwidth exceeding 22 GHz, supports back-to-back data rates up to 50 Gbps at 25 °C and 40 Gbps at 85 °C under binary NRZ (OOK) modulation. Using mode-selective launch, we demonstrate error-free 25 Gbps transmission over 1000 m of 1060 nm optimized MMF. Higher data rates and/or longer distances will be possible with equalization, forward-error-correction, and/or multilevel modulation.
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| 3. |
- Larsson, Anders, 1957, et al.
(författare)
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High-Speed VCSELs for Datacom
- 2016
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Ingår i: Proceedings European Conference on Optical Communication. - 9783800742745 ; , s. 977-979
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Konferensbidrag (refereegranskat)
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| 4. |
- Larsson, Anders, 1957, et al.
(författare)
-
High-Speed VCSELs for OOK and Multilevel PAM Modulation
- 2017
-
Ingår i: 30TH ANNUAL CONFERENCE OF THE IEEE PHOTONICS SOCIETY (IPC). - 2374-0140. - 9781509065783 ; 2017-January, s. 355-356
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Konferensbidrag (refereegranskat)abstract
- The short-reach optical interconnects used in datacenters and high-performance computing systems are dominated by vertical-cavity surface-emitting laser (VCSEL) and multimode fiber (MMF) links1. The VCSEL-MMF technology is the most cost and power efficient and offers the smallest footprint. VCSELs for 25-28 Gbit/s OOK lanes are in production2 while 25-28 Gbaud PAM-4 with forward-error-correction (FEC) is considered for next generation 50-56 Gbit/s lanes3. For this transition, as well as future developments towards even higher speed, the VCSEL dynamics and high-speed properties are of utmost importance. Improved dynamics may enable 50-56 Gbit/s PAM-4 without FEC and even 50-56 Gbit/s OOK, which would reduce complexity, power consumption, and latency.
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| 5. |
- Larsson, Anders, 1957, et al.
(författare)
-
VCSEL design and integration for high-capacity optical interconnects
- 2017
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781510606593 ; 10109, s. 101090M-
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Konferensbidrag (refereegranskat)abstract
- Vertical-cavity surface-emitting lasers and multi-mode fibers is the dominating technology for short-reach optical interconnects in datacenters and high performance computing systems at current serial rates of up to 25-28 Gbit/s. This is likely to continue at 50-56 Gbit/s. The technology shows potential for 100 Gbit/s.
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| 6. |
- Larsson, Anders, 1957, et al.
(författare)
-
VCSEL modulation capacity: Continued improvements or physical limits?
- 2017
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Ingår i: 6th IEEE Photonics Society Optical Interconnects Conference, OI 2017. - 9781509050154 ; , s. 53-54
-
Konferensbidrag (refereegranskat)abstract
- The short-reach optical interconnects used in datacenters and high-performance computing systems are dominated by VCSEL and multimode fiber (MMF) links 1 . The VCSEL-MMF technology is the most cost and power efficient and offers the smallest footprint. VCSELs operating at 25-28 Gbit/s are in production 2 while research has extended the VCSEL modulation bandwidth to 30 GHz 3 (Fig.1) and enabled OOK-NRZ data transmission up to 57 Gbit/s at 25°C 4 and 50 Gbit/s at 85°C 5 , without equalization or forward-error-correction (FEC). A VCSEL energy dissipation below 100 fJ/bit has been demonstrated at 25-50 Gbit/s 3 (Fig.1). The need for higher interconnect capacity raises the question whether the speed and dynamics of VCSELs can be further improved or whether physical limits preventing this have been reached. Higher speed VCSELs would enable higher lane rates and therefore reduced number of lanes and increased bandwidth density for a given aggregate interconnect capacity.
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| 7. |
- Larsson, Anders, 1957, et al.
(författare)
-
VCSEL modulation speed: Status and prospects
- 2019
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10938
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Konferensbidrag (refereegranskat)
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| 8. |
- Lavrencik, Justin, et al.
(författare)
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Error-Free 100Gbps PAM-4 Transmission over 100m OM5 MMF using 1060nm VCSELs
- 2019
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. ; Part F160-OFC 2019
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate error-free (BER <10 -12 ) rates beyond 100Gbps over 100m OM5 using unpackaged 1060nm VCSELs. Power penalties of PAM-2/PAM-4 are examined demonstrating OM5 fiber capacity to support wavelengths to 1060nm with only transmitter equalization.
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| 9. |
- Lavrencik, Justin, et al.
(författare)
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Error-free 850nm to 1060nm VCSEL links: Feasibility of 400Gbps and 800Gbps 8λ-SWDM
- 2019
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Ingår i: IET Conference Publications. - 9781839530074 ; 2019
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Konferensbidrag (refereegranskat)abstract
- We demonstrate effective transmitter equalization for 850nm, 980nm, and 1060nm VCSELs and 100m OM5 links enabling 78Gbps PAM-2 and >100Gbps PAM-4 100m error free links. Extracted link penalties reveal net fibre dispersion and RIN enhancement create small to negligible power penalties for all wavelengths.
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| 10. |
- Lengyel, Tamas, 1986, et al.
(författare)
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Pre-emphasis enabled 50 Gbit/s transmission over 1000 m SMF using a 1060 nm single-mode VCSEL
- 2018
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 54:20, s. 1186-1187
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Tidskriftsartikel (refereegranskat)abstract
- A single-mode 1060 nm vertical-cavity surface-emitting laser (VCSEL) and single-mode fibre (SMF) based link with two-tap active pre-emphasis enabling error-free transmission of 50 Gbit/s NRZ-OOK over 1000 m is presented.
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| 11. |
- Simpanen, Ewa, 1987
(författare)
-
1060 nm GaAs VCSELs for Extended Reach Optical Interconnects in Data Centers
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The data centers of today are increasing in size and are built to accommodate strong data traffic demands while providing sustainably by having clients sharing resources under one roof. Their massive scale puts pressure on the server network topology and has incited a need for data transmission links that are energy efficient and capable to operate at high bit rates with reach up to a few kilometers. Optical interconnects (OIs) offer large bandwidth and low attenuation at long distances, and are therefore suitable for this task. The most commonly used OIs, with 850 nm GaAs-based vertical-cavity surface-emitting lasers (VCSELs) and multi-mode fiber (MMF), have a 25 Gb/s reach that is limited to a few hundred meters. However, the fiber chromatic dispersion and attenuation that limit the OI reach can be reduced significantly by increasing the wavelength of this very same technology. The upper limit of the GaAs-based VCSEL technology, with strained InGaAs quantum wells (QWs), is about 1100 nm. With further improved OI performance, new hyperscale data center topologies can be realized and explored. This will lead to many more possible solutions in traffic engineering as well as for power management. 1060 nm VCSELs could open up for lane rates of 10, 25 and possibly 50 Gb/s over distances up to 2 km and help reach the Tb/s link speed aim of the Ethernet standard. In this work we show that the 1060 nm GaAs VCSEL is a suitable light source for long-reach OIs by demonstrating its overall stable performance and capability of error-free data transmission up to 50 Gb/s back-to-back and 25 Gb/s over 1 km of MMF. These results stem from careful VCSEL design, including strained InGaAs QWs with GaAsP barriers, doped AlGaAs distributed Bragg reflectors, a short op-tical cavity and multiple oxide layers. We also show that the fabrication of such a device poses no increase in complexity and can be realized using standard processing techniques.
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| 12. |
- Simpanen, Ewa, 1987, et al.
(författare)
-
1060 nm single and multimode VCSELs for up to 50 Gb/s modulation
- 2017
-
Ingår i: Proceedings of IEEE Photonics Conference 2017. - : IEEE. - 9781509065776 ; 2017-January, s. 65-66
-
Konferensbidrag (refereegranskat)abstract
- We present the design and performance of 1060 nm VCSELs with up to 50 Gb/s intrinsic speed and demonstrate 25 Gb/s transmission over 1000 m of 1060 nm optimized MMF using a single-mode VCSEL and mode-selective launch.
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| 13. |
- Simpanen, Ewa, 1987, et al.
(författare)
-
1060 nm Single-Mode VCSEL and Single-Mode Fiber Links for Long-Reach Optical Interconnects
- 2019
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 37:13, s. 2963-2969
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the use of a 1060 nm single-mode vertical-cavity surface-emitting laser (VCSEL) and a 1060 nm single-mode fiber as a competitive single-mode technology for cost-and power-efficient long-reach optical interconnects. Error-free transmission (bit error rate < 10-12) over 2 km is demonstrated at bitrates up to 40 Gb/s under on-off keying non-return-to-zero (OOK-NRZ) modulation, without equalization, forward-error correction, or other forms of digital signal processing. The VCSEL is extensively characterized with respect to its static and dynamic performances, including the power-voltage-current characteristics, spectral characteristics, beam divergence, modulation response, relative intensity noise, and frequency chirp. The measured dependence of power penalty on fiber length is consistent with an analysis of chirp-induced pulse compression and broadening along the negative chromatic dispersion fiber.
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| 14. |
- Simpanen, Ewa, 1987, et al.
(författare)
-
1060 nm single-mode vertical-cavity surface-emitting laser operating at 50 Gbit/s data rate
- 2017
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 53:13, s. 869-870
-
Tidskriftsartikel (refereegranskat)abstract
- An energy efficient 1060 nm GaAs-based oxide-confined vertical-cavity surface-emitting laser designed for high-speed modulation and singlemode emission has been developed. A record data rate of 50 Gbit/ s at an energy dissipation of 100 fJ/ bit is demonstrated for a device with > 50 dB side-mode-suppression and 0.2 mA threshold current, making this laser a promising light source for long-reach optical interconnects.
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| 15. |
- Simpanen, Ewa, 1987, et al.
(författare)
-
1060 nm VCSEL for up to 40 Gbit/s Data Transmission
- 2016
-
Ingår i: Conference Digest - IEEE International Semiconductor Laser Conference. - 0899-9406. - 9784885523069 ; , s. Article no 7765757-
-
Konferensbidrag (refereegranskat)abstract
- A GaAs-based 1060 nm VCSEL with strained InGaAs/GaAsP QWs, doped DBRs, a short optical cavity, and multiple oxide apertures is presented. Modulation up to 40 Gbit/s at 25°C and 30 Gbit/s at 85°C is demonstrated.
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| 16. |
- Simpanen, Ewa, 1987, et al.
(författare)
-
Long-Reach 1060 nm SM VCSEL - SMF Optical Interconnects
- 2018
-
Ingår i: European Conference on Optical Communication, ECOC. ; 2018-September
-
Konferensbidrag (refereegranskat)abstract
- We explore the low-cost, low-power GaAs-VCSEL technology for long-reach interconnects at 1060 nm. With reduced fiber attenuation and chromatic dispersion compared to 850 nm, we demonstrate error-free 40 Gbps OOK-NRZ transmission over 2 km SMF using a SM VCSEL.
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| 17. |
- Simpanen, Ewa, 1987
(författare)
-
Longer Wavelength GaAs-Based VCSELs for Extended-Reach Optical Interconnects
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Data centers of today are increasing in size and are built to accommodate strong traffic demands while providing sustainably by having clients sharing resources under one roof. Their massive scale puts pressure on the server network topology and has incited a need for data transmission links that are energy efficient and capable of operation at high bit rates with reach up to a few kilometers. Optical interconnects (OIs) offer large bandwidth and low attenuation at long distances, and are therefore suitable for this task. The most commonly used OIs, with 850 nm GaAs-based vertical-cavity surface-emitting lasers (VCSELs) and multi-mode fiber (MMF), have a 25 Gb/s reach that is limited to a few hundred meters. However, the fiber chromatic dispersion and attenuation that limit the OI reach can be reduced significantly by increasing the wavelength of this very same technology. The upper limit of the GaAs-based VCSEL technology, with strained InGaAs quantum wells (QWs), is about 1100 nm. With further improved OI performance, new hyperscale data center topologies can be realized and explored. This will lead to a larger number of possible solutions in traffic engineering as well as for power management. 1060 nm VCSELs could soon open up for lane rates of 100+ Gb/s over distances up to 2 km and help reach the Tb/s link speed aim of data center OI standards, in which capacity is built up mainly by employing multiple parallel lanes, increasing symbol rate by going from binary to four-level pulse amplitude modulation (PAM-4), and optimizing with electrical mitigation techniques such as digital signal processing. In this work we show that 1060 nm GaAs VCSELs are suitable light sources for long-reach OIs by first demonstrating their overall stable performance and capability of error-free data transmission up to 50 Gb/s back-to-back and 25 Gb/s over 1 km of MMF. With PAM-4, we show 100 Gb/s error-free capability over 100 m of MMF, suitable for wavelength division multiplexed OIs that can transmit data at several wavelengths from 850 to 1060 nm over the same fiber channel. We also assemble single-mode 1060 nm VCSEL and single-mode fiber links and demonstrate 50 Gb/s error-free transmission over 1 km using pre-emphasis and 40 Gb/s over 2 km without the use of any electrical mitigation techniques. These results stem from careful VCSEL design, including strained InGaAs QWs with GaAsP barriers, doped AlGaAs distributed Bragg reflectors, a short optical cavity and multiple oxide layers. In addition, we show that the fabrication of such a device poses no increase in complexity and can be realized using standard processing techniques.
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| 18. |
- Simpanen, Ewa, 1987, et al.
(författare)
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Noise Performance of Single-Mode VCSELs: Dependence on Current Confinement and Optical Loss
- 2020
-
Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 56:5
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the intensity and phase noise properties of GaAs-based 1060 nm oxide-confined single-mode vertical-cavity surface-emitting lasers (VCSELs) and their dependence on slope efficiency and current spreading, parameters that control the achievable output power. We find strong dependence of the linewidth on slope efficiency because it affects the optical resonator loss and therefore the spontaneous emission rate and the photon density. Likewise, we find strong dependence of the relative intensity noise on the slope efficiency since the optical resonator loss controls the photon lifetime, and therefore the damping of the relaxation oscillations. There is no noticeable dependence on transverse current confinement and current spreading. We measure linewidths as small as 6 MHz which we attribute to a small linewidth enhancement factor. This assumption is supported by calculations of the linewidth enhancement factor from optical resonator and optical gain simulations. The dependencies of noise on design parameters are general and therefore valid for single-mode VCSELs at other wavelengths and in other material systems.
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