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Journal ArticleDOI

140/180/204-Gbaud OOK Transceiver for Inter- and Intra-Data Center Connectivity

TL;DR: An on–off keying intensity-modulation and direct-detection C-band optical transceiver capable of addressing all datacenter interconnect environments at well beyond 100 Gbaud is reported on, drawing conclusions from the observed system-level limitations of the respective environments at this ultrahigh baudrate.
Abstract: We report on an on – off keying intensity-modulation and direct-detection C-band optical transceiver capable of addressing all datacenter interconnect environments at well beyond 100 Gbaud. For this, the transmitter makes the use of two key InP technologies: a 2:1 double heterojunction bipolar transistor selector multiplexer and a monolithically integrated distributed-feedback laser traveling-wave electro-absorption modulator, both exceeding 100-GHz of 3-dB analog bandwidth. A preamplified 110-GHz PIN photodiode prior to a 100-GHz analog-to-digital converter complete the ultrahigh bandwidth transceiver module; the device under study. In the experimental work, which discriminates between intra- and inter-data center scenarios (dispersion unmanaged 120, 560, and 960 m; and dispersion-managed 10 and 80 km of standard single-mode fiber), we evaluate the bit-error rate evolution against the received optical power at 140, 180, and 204 Gbaud on – off keying for different equalization configurations (adaptive linear filter with and without the help of short-memory sequence estimation) and forward error correction schemes (hard-decision codes with 7% and 20% overhead); drawing conclusions from the observed system-level limitations of the respective environments at this ultrahigh baudrate, as well as from the operation margins and sensitivity metrics. From the demonstration, we highlight three results: successful operation with >6-dB sensitivity margin below the 7% error-correction at 140 Gbaud over the entire 100 m–80 km range with only linear feed-forward equalization. Then, the transmission of a 180-Gbaud on – off keying carrier over 80 km considering 20% error-correction overhead. Finally, a 10-km communication at 204 Gbaud on – off keying with up to 6 dB sensitivity margin, and regular 7% overhead error-correction.
Citations
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Journal ArticleDOI
15 Jan 2020
TL;DR: This article focuses on IM/DD transmissions, and provides an overview of recent research and development efforts on key enabling technologies for 200 Gbps per lane and beyond, and expects high-speed IM/ DD systems will remain advantageous in terms of system cost, power consumption, and footprint for short reach applications in the short- to mid- term perspective.
Abstract: Client-side optics are facing an ever-increasing upgrading pace, driven by upcoming 5G related services and datacenter applications. The demand for a single lane data rate is soon approaching 200 Gbps. To meet such high-speed requirement, all segments of traditional intensity modulation direct detection (IM/DD) technologies are being challenged. The characteristics of electrical and optoelectronic components and the performance of modulation, coding, and digital signal processing (DSP) techniques are being stretched to their limits. In this context, we witnessed technological breakthroughs in several aspects, including development of broadband devices, novel modulation formats and coding, and high-performance DSP algorithms for the past few years. A great momentum has been accumulated to overcome the aforementioned challenges. In this article, we focus on IM/DD transmissions, and provide an overview of recent research and development efforts on key enabling technologies for 200 Gbps per lane and beyond. Our recent demonstrations of 200 Gbps short-reach transmissions with 4-level pulse amplitude modulation (PAM) and discrete multitone signals are also presented as examples to show the system requirements in terms of device characteristics and DSP performance. Apart from digital coherent technologies and advanced direct detection systems, such as Stokes–vector and Kramers–Kronig schemes, we expect high-speed IM/DD systems will remain advantageous in terms of system cost, power consumption, and footprint for short reach applications in the short- to mid- term perspective.

99 citations


Cites methods from "140/180/204-Gbaud OOK Transceiver f..."

  • ...III, the DFB-TWEAM was also employed for a 204 Gbaud OOK transmission, where two 2:1 InP DHBT multiplexing selector was used to generate the highbaud rate OOK signal [113], [114]....

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  • ...100-GHz DFB-TWEAM C-band 204 OOK 10-km SMF +DCF LUT, MAP 5E-3 [113][114]...

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Journal ArticleDOI
TL;DR: In this paper, a membrane distributed reflector laser on a low-refractive-index and high-thermal-conductivity silicon carbide substrate was proposed to achieve a 42 GHz relaxation oscillation frequency.
Abstract: Increasing the modulation speed of semiconductor lasers has attracted much attention from the viewpoint of both physics and the applications of lasers. Here we propose a membrane distributed reflector laser on a low-refractive-index and high-thermal-conductivity silicon carbide substrate that overcomes the modulation bandwidth limit. The laser features a high modulation efficiency because of its large optical confinement in the active region and small differential gain reduction at a high injection current density. We achieve a 42 GHz relaxation oscillation frequency by using a laser with a 50-μm-long active region. The cavity, designed to have a short photon lifetime, suppresses the damping effect while keeping the threshold carrier density low, resulting in a 60 GHz intrinsic 3 dB bandwidth (f3dB). By employing the photon–photon resonance at 95 GHz due to optical feedback from an integrated output waveguide, we achieve an f3dB of 108 GHz and demonstrate 256 Gbit s−1 four-level pulse-amplitude modulations with a 475 fJ bit−1 energy cost of the direct-current electrical input. Directly modulated membrane distributed reflector lasers are fabricated on a silicon carbide platform. The 3 dB bandwidth, four-level pulse-amplitude modulation speed and operating energy for transmitting one bit are 108 GHz, 256 Gbit s−1 and 475 fJ, respectively.

99 citations

Journal ArticleDOI
01 Jun 2020
TL;DR: A monolithically integrated electro-optical transmitter that can achieve symbol rates beyond 100 GBd is reported, and addresses key challenges in monolithic integration through co-design of the electronic and plasmonic layers, including thermal design, packaging and a nonlinear organic Electro-optic material.
Abstract: To address the challenge of increasing data rates, next-generation optical communication networks will require the co-integration of electronics and photonics. Heterogeneous integration of these technologies has shown promise, but will eventually become bandwidth-limited. Faster monolithic approaches will therefore be needed, but monolithic approaches using complementary metal–oxide–semiconductor (CMOS) electronics and silicon photonics are typically limited by their underlying electronic or photonic technologies. Here, we report a monolithically integrated electro-optical transmitter that can achieve symbol rates beyond 100 GBd. Our approach combines advanced bipolar CMOS with silicon plasmonics, and addresses key challenges in monolithic integration through co-design of the electronic and plasmonic layers, including thermal design, packaging and a nonlinear organic electro-optic material. To illustrate the potential of our technology, we develop two modulator concepts—an ultra-compact plasmonic modulator and a silicon-plasmonic modulator with photonic routing—both directly processed onto the bipolar CMOS electronics. The monolithic integration of electronic and plasmonic technologies can be used to create electro-optic transmitters capable of symbol rates beyond 100 GBd.

78 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate a 222 GBd on-off-keying transmitter in a short-reach intra-datacenter scenario with direct detection after 120m of standard single mode fiber.
Abstract: We demonstrate a 222 GBd on-off-keying transmitter in a short-reach intra-datacenter scenario with direct detection after 120 m of standard single mode fiber. The system operates at net-data rates of >200 Gb/s OOK for transmission distances of a few meters, and >177 Gb/s over 120 m, limited by chromatic dispersion in the standard single mode fiber. The high symbol rate transmitter is enabled by a high-bandwidth plasmonic-organic hybrid Mach–Zehnder modulator on the silicon photonic platform that is ribbon-bonded to an InP DHBT 2:1 digital multiplexing selector. Requiring no driving RF amplifiers, the selector directly drives the modulator with a differential output voltage of 622 mVpp measured across a 50 Ω resistor. The transmitter assembly occupies a footprint of less than 1.5 mm × 2.1 mm.

42 citations


Cites background from "140/180/204-Gbaud OOK Transceiver f..."

  • ...The EAM concept has been proved mainly on two platforms, indium phosphide [3], [4] and germanium silicon [7], [8]....

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  • ...To realize densely integrated transceivers a low power load is required [3], [4], which can be realized by modulators with low driving voltages and the...

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Journal ArticleDOI
TL;DR: A new plasmonic Mach-Zehnder modulator is demonstrated at a bit rate of 120 Gb/s NRZ-OOK with low peak-to-peak driving voltages of 178 mVpp below the HD-FEC limit, potentially translating into an electrical drive power consumption of 862 aJ/bit.
Abstract: A new plasmonic Mach-Zehnder modulator is demonstrated at a bit rate of 120 Gb/s NRZ-OOK with low peak-to-peak driving voltages of 178 mVpp below the HD-FEC limit. Such record low driving voltage requirements potentially translate into an electrical drive power consumption of 862 aJ/bit. The low drive voltages have been made possible by a new differential Mach-Zehnder modulator electrode design. The differential electrode design is optimized for the balanced driving circuitry and reduces the effectively required driving voltage by a factor of four (Vπ/4). The potential of the transmitter scheme is further demonstrated by a transmission experiment over 500 m of single mode fiber at the C-band with a BER performance below the KP4 FEC limit.

38 citations

References
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Journal ArticleDOI
TL;DR: The identification of fundamental scaling disparities between the technologies used to generate and process data and those used to transport data could lead to the data transport network falling behind its required capabilities by a factor of approximately 4 every five years, leading to an optical network capacity crunch.
Abstract: Based on a variety of long-term network traffic data from different geographies and applications, in addition to long-term scaling trends of key information and communication technologies, we identify fundamental scaling disparities between the technologies used to generate and process data and those used to transport data. These disparities could lead to the data transport network falling behind its required capabilities by a factor of approximately 4 every five years. By 2024, we predict the need for 10-Tb/s optical interfaces working in 1-Pb/s optical transport systems. To satisfy these needs, multiplexing in both wavelength and space in the form of a wavelength-division multiplexing × space-division multiplexing matrix will be required. We estimate the characteristics of such systems and outline their target specifications, which reveals the need for very significant research progress in multiple areas, from system and network architectures to digital signal processing to integrated arrayed device designs, in order to avoid an optical network capacity crunch.

329 citations


"140/180/204-Gbaud OOK Transceiver f..." refers background in this paper

  • ...circuits and hardware components [28]; and with photonic integration and digital-optical co-packaging further consolidating their relevance in the short-reach market [8], the transceiver and...

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  • ...Supported by more and more costeffective and high-speed digital processors [8] enabling lowlatency forward error correction (FEC) and electronic impair-...

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Journal ArticleDOI
TL;DR: An overview of recent DSP developments for short-reach communications systems is presented and future trends are discussed.
Abstract: Driven primarily by cloud service and data-center applications, short-reach optical communication has become a key market segment and growing research area in recent years. Short-reach systems are characterized by direct detection-based receiver configurations and other low-cost and small form factor components that induce transmission impairments unforeseen in their coherent counterparts. Innovative signaling and digital signal processing (DSP) play a pivotal role in enabling these components to realize their ultimate potentials and meet data rate requirements in cost-effective manners. This paper presents an overview of recent DSP developments for short-reach communications systems and discusses future trends.

319 citations

Journal ArticleDOI
TL;DR: A plasmonic Mach-Zehnder (MZ) modulator with a flat frequency response exceeding 170 GHz is demonstrated and is relevant for next-generation optical interconnects.
Abstract: We demonstrate a plasmonic Mach-Zehnder (MZ) modulator with a flat frequency response exceeding 170 GHz. The modulator comprises two phase modulators exploiting the Pockels effect of an organic electro-optic material in plasmonic slot waveguides. We further show modulation at 100 GBd NRZ and 60 GBd PAM-4. The electrical drive signals were generated using a 100 GSa/s digital to analog converter (DAC). The high-speed and small-scale devices are relevant for next-generation optical interconnects.

133 citations


"140/180/204-Gbaud OOK Transceiver f..." refers background in this paper

  • ..., Si [15], Si-organic hybrid [16], plasmonicorganic hybrid [17], InP [18], [19], or LiNbO3 [20]; as well as driving electronics, digital samplers, and multiplexors – e....

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Journal ArticleDOI
TL;DR: In this paper, the authors review experimental demonstrations of Kramers-Kronig (KK) based direct detection systems with high per-carrier interface rates, high spectral efficiencies, and ∼100-km reach.
Abstract: In this paper, we review in detail experimental demonstrations of Kramers–Kronig (KK) based direct detection systems with high per-carrier interface rates, high spectral efficiencies, and ∼100-km reach Two realizations of KK-based receivers are summarized, including single-polarization and dual-polarization versions Critical aspects of the KK receiver such as the carrier-to-signal power ratio and receiver bandwidth limitations are discussed We show 220-Gb/s single-diode detection and 4 × 240-Gb/s dual polarization (dual-diode) detection in a WDM system at 53 bits/s/Hz spectral efficiency

129 citations


"140/180/204-Gbaud OOK Transceiver f..." refers background in this paper

  • ...Research work on the latter includes [38], which reviews several high-speed 100-km experiments exploiting the Kramers-Kronig relations to linearize the channel, and [39], which targets the same through manipulation and detection of the Stokes vectors....

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Journal ArticleDOI
Di Che1, An Li1, Xi Chen1, Qian Hu1, Yifei Wang1, William Shieh1 
TL;DR: In this paper, the Stokes vector direct detection (SV-DD) was proposed to realize a linear complex optical channel similar to the coherent detection, where the transmitter places the signal and the carrier onto the orthogonal polarizations, while the receiver achieves the polarization insensitive 3-D detection in the stokes space with the digital signal processing enabled polarization acquisition.
Abstract: Data center interconnect has stimulated the research on the short-reach communications with data rate beyond 100G per wavelength and transmission distance of hundreds of kilometers. Aiming at the high-speed short-reach communications, we recently proposed the Stokes vector direct detection (SV-DD) that realizes a linear complex optical channel similar to the coherent detection. In SV-DD, the transmitter places the signal and the carrier onto the orthogonal polarizations, while the receiver achieves the polarization insensitive 3-D detection in the Stokes space with the digital signal processing enabled polarization acquisition. SV-DD achieves 100% spectral efficiency with reference to the single-polarization coherent detection, and simultaneously attains the receiver phase diversity and the cancellation of photo-detection nonlinearity. We experimentally demonstrate the SV-DD signal transmission over 160-km standard single-mode fiber at data rates of both 80 and 160-Gb/s. SV-DD significantly decreases both the system hardware and DSP complexity compared with the polarization multiplexed coherent detection, while increases the system spectrum efficiency compared with the conventional intensity modulation direct detection. Therefore, SV-DD offers a cost-effective solution for the 100G per wavelength and beyond metropolitan area network (MAN). It also owns the potentials to be deployed in the future high-speed passive optical network (PON).

91 citations


"140/180/204-Gbaud OOK Transceiver f..." refers background in this paper

  • ...Research work on the latter includes [38], which reviews several high-speed 100-km experiments exploiting the Kramers-Kronig relations to linearize the channel, and [39], which targets the same through manipulation and detection of the Stokes vectors....

    [...]

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