| 31. |
- Börjeson, Erik, 1984, et al.
(författare)
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VLSI Implementations of Carrier Phase Recovery Algorithms for M-QAM Fiber-Optic Systems
- 2020
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:14, s. 3616-3623
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Tidskriftsartikel (refereegranskat)abstract
- We present circuit implementations of blind phase search (BPS) carrier phase recovery (CPR) for M-QAM coherent optical receivers and highlight some BPS algorithm modifications necessary to obtain efficient VLSI circuits. In addition, we show how three key design parameters (input word length, number of test phases, and type and size of averaging window) affect the resulting implementation. To study design tradeoffs, we develop BPS CPR circuit netlists for a 32-GBaud system, using a 22-nm CMOS process technology: Our implementations reach energy efficiencies of around 1 pJ/bit for 16QAM up to 3 pJ/bit for 256QAM, at an SNR penalty of approximately 0.25 dB at a BER of 10^(−2). Furthermore, we present a circuit implementation of pilot-symbol-aided CPR, reaching 0.38 pJ/bit and 0.34 pJ/bit for 16QAM and 256QAM, respectively, at a slightly higher SNR penalty. The two CPR methods are also evaluated in terms of silicon area and scaling to higher-order modulation formats.
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| 32. |
- Campi, Roberta, et al.
(författare)
-
Highly reliable and high-yield 1300-nm InGaAlAs directly modulated ridge fabry-Perot lasers, operating at 10-gb/s, up to 110°C, with constant current swing
- 2006
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 24:1, s. 143-149
-
Tidskriftsartikel (refereegranskat)abstract
- Transceivers for 300-m multimode links, based on a serial 10-Gb/s laser source and incorporating a receiver based on electronic dispersion compensation (EDC), are creating the first high-volume application for a 10-Gb Fabry-Perot (FP). A highly reliable and high-yield uncooled ridge FP laser is presented. The device shows excellent power characteristics in the 25 divided by 150 degrees C temperature range with very high To (95 K in the temperature range 0 divided by 85 C and still 78 K at 150 degrees C). Outstanding dynamic performances are also shown: 6 dB of extinction ratio can be achieved up to 110 degrees C by using a constant current swing of 50 mA. Because of their enhanced performances, these devices have enabled single temperature setting of the optical module, leading to a significant test cost reduction.
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| 33. |
- Carlsson, C., et al.
(författare)
-
Analog modulation properties of oxide confined VCSELs at microwave frequencies
- 2002
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 20:9, s. 1740-1749
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the need for affordable, high-performance fiber-optic microwave links in fiber-fed microcellular networks and radar systems, we have performed a comprehensive experimental evaluation of the microwave modulation characteristics of high-speed oxide-confined vertical cavity surface emitting lasers (VCSELs) emitting at 840 inn. VCSELs with different oxide aperture diameters, including both single- and multimode lasers, have been used to track the dependence on modal behavior. The study includes both static and dynamic characteristics, with an emphasis on those of major importance for analog modulation. This includes the small-signal modulation response (S-11 and S-21), the relative intensity noise (RIN), and the intermodulation distortion. From this, we determine the spurious free dynamic range, the impedance characteristics, and the speed limitations.
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| 34. |
- Carlsson, Christina, 1975, et al.
(författare)
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RF transmission over multimode fibers using VCSELs-comparing standard and high bandwidth multimode fibers
- 2004
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 22:7, s. 1694-1700
-
Tidskriftsartikel (refereegranskat)abstract
- Fiber-optic radio-frequency links have been assembled using oxide-confined vertical-cavity surface-emitting lasers (VCSELs) and multimode fibers. Links with single and multimode VCSELs and with standard and high-bandwidth fibers have been evaluated and compared in the frequency range of 0.1-10 GHz. The best results were obtained for links with a multimode VCSEL and a high-bandwidth fiber. For a 500-m-long link, a spurious free dynamic range of 104 dB. HZ(2/3) at 2 GHz and 100 dB (.) Hz(2/3) at 5, GHz were obtained while allowing for a VCSEL-fiber misalignment of +/-12 mum. Corresponding numbers for the intrinsic link gain and noise figure are -29 and -33 dB, and 39 and 42 dB at 2 and 5 GHz, respectively. Inferior performance Was observed for the standard fiber link due to a larger variation in modal group velocities. This paper also presents a detailed link analysis to identify performance limitations and to suggest modifications for improved performance.
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| 35. |
- Castro, J. M., et al.
(författare)
-
Investigation of 60 Gb/s 4-PAM Using an 850 nm VCSEL and Multimode Fiber
- 2016
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 34:16, s. 3825-3836
-
Tidskriftsartikel (refereegranskat)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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| 36. |
- Caut, Alexander, 1994, et al.
(författare)
-
Angled Flip-Chip Integration of VCSELs on Silicon Photonic Integrated Circuits
- 2022
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 40:15, s. 5190-5200
-
Tidskriftsartikel (refereegranskat)abstract
- An investigation of angled flip-chip integration of a singlemode 850 nm vertical-cavity surface-emitting laser (VCSEL) on a silicon nitride photonic integrated circuit (PIC) is presented. Using numerical FDTD simulations, we consider the conditions under which the VCSEL can be integrated at an angle over a grating coupler with high coupling efficiency and low optical feedback. With both coupling efficiency and feedback decreasing with increasing angle, there is a trade-off. With co-directional coupling, first-order diffraction loss sets in at a critical angle, which further reduces the coupling efficiency. No such critical angle exists for contra-directional coupling. We also experimentally demonstrate angled flip-chip integration of GaAs-based 850 nm single transverse and polarization mode VCSELs over grating couplers on a silicon-nitride PIC. At the output grating coupler, light is either collected by an optical fiber or converted to a photocurrent using a flip-chip integrated GaAs-based photodetector. The latter forms an on-PIC optical link. We measured an insertion loss of 21.9, 17.6 and 20.1 dB with a singlemode fiber, multimode fiber and photodetector over the output grating coupler, respectively.
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| 37. |
- Caut, Alexander, 1994, et al.
(författare)
-
Channel Scalability of Silicon Nitride (De-)multiplexers for Optical Interconnects at 1 μm
- 2024
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 42:1, s. 276-286
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an investigation of the channel scalability of silicon nitride (Si3N4)-based (de-)multiplexers in the 1-μm band (1015-1055 nm). We discuss 4-, 8- and 16-channel demultiplexers based on arrayed waveguide gratings (AWGs) and cascaded Mach-Zehnder interferometers (MZIs), with corresponding channel spacings of 8, 4 and 2 nm. Gaussian and flat-top response devices are considered for both technologies and we analyze the insertion loss, temperature sensitivity, response flatness, footprint and crosstalk (XT). We study the impact of the number of channels on the insertion loss and XT level. In the experimental part, we demonstrate a 4-channel Gaussian AWG. We also demonstrate 4-channel Gaussian and flat-top cascaded MZIs, based on multimode interferometers (MMIs) and directional couplers (DCs). The AWG is attractive due to its small footprint but its high manufacturing complexity makes the device more prone to fabrication defects, which can lead to higher loss and higher XT. For the Gaussian AWG and MZI, the XT level is approximately the same and increases with the number of channels from -28 to -23 dB at 4 and 16 channels respectively. The flat-top MZI has no extra-loss with respect to the flat-top AWG and has a better tolerance to high temperature operations. However, due to wavelength sensitive DCs, the XT of the flat-top MZI is higher than that of the flat-top AWG except for a 16-channel system.
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| 38. |
- Cavdar, Cicek, 1977-, et al.
(författare)
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Shared-Path Protection With Delay Tolerance (SDT) in Optical WDM Mesh Networks
- 2010
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:14, s. 2068-2076
-
Tidskriftsartikel (refereegranskat)abstract
- Optical wavelength-division-multiplexing (WDM) networks have emerged as an ideal backbone for the dynamic transport of bandwidth-intensive applications. Most emerging applications require end-to-end survivable connections to be set up for specific time durations that have sliding or fixed setup times (such as IPTV, grid computing backup storage). It is critical for the development of future network infrastructure that user-centric, dynamic, and end-to-end management and control mechanisms are devised to bridge the gap between the transport capacity and the needs of new applications at the customer edges. In this paper, we study the problem of dynamic provisioning of user-controlled connection requests that have specified holding times and delay tolerances. Delay tolerance is a measure of customer patience, and it is defined as the duration a connection request can be held until it is set up. A connection that cannot be established at the instant of its request could potentially be set up in the remaining duration of its delay tolerance. In this study, different dynamic scheduling algorithms are developed and compared by giving priority to connections according to their arrival rates, delay tolerances, and holding times. Using a mathematical model for impatient requests and simulation experiments, we show that delay tolerance flexibility in the traffic model provides a reduction of up to 50% on blocking probability, without the use of extra backup capacity.
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| 39. |
- Cen, Min, et al.
(författare)
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Advanced Fault-Monitoring Scheme for Ring-Based Long-Reach Optical Access Networks
- 2017
-
Ingår i: Journal of Lightwave Technology. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0733-8724 .- 1558-2213. ; 35:10, s. 1876-1886
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel fiber fault-monitoring system for long-reach optical access networks based on a transmission-reflection analysis approach. By launching an un-modulated continuous-wave optical signal into the feeder ring and measuring the transmitted and reflected/backscattered optical powers, the proposed monitoring scheme is able to detect, identify, and localize any major fault (covering both reflective and nonreflective events) with a good spatial accuracy (<= 10 m) and a high detection speed (3 s). Both experimental and simulation results have demonstrated that the proposed system provides fiber monitoring functionality better than that obtained by the conventional methods.
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| 40. |
- Chacinski, Marek, et al.
(författare)
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Monolithically Integrated 100 GHz DFB-TWEAM
- 2009
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 7:16, s. 3410-3415
-
Tidskriftsartikel (refereegranskat)abstract
- A monolithically integrated distributed feedback (DFB) laser and traveling-wave electro-absorption modulator (TWEAM) with >= 100 GHz -dBe bandwidth suitable for Non-return-to-zero (NRZ) operation with on-off keying (OOK) is presented. The steady-state, small-signal modulation response, microwave reflection, chirp characteristic, and both data operation and transmission were investigated. The DFB-TWEAM was found to be an attractive candidate for future short distance communication in high bitrates systems.
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