Showing papers on "Wavelength-division multiplexing published in 2015"

2.15 Pb/s transmission using a 22 core homogeneous single-mode multi-core fiber and wideband optical comb

Abstract: We use a wideband optical comb source with 10THz bandwidth for 2.15 Pb/s transmission over 31km of a new, homogeneous 22-core single-mode multi-core fiber using 399 × 25GHz spaced, 6.468 Tb/s spatial-super-channels comprising 24.5GBaud PDM-64QAM modulation in each core.

NG-PON2 Technology and Standards

Abstract: This paper provides a tutorial overview of the latest generation of passive optical network (PON) technology standards nearing completion in ITU-T. The system is termed NG-PON2 and offers a fiber capacity of 40 Gbit/s by exploiting multiple wavelengths at dense wavelength division multiplexing channel spacing and tunable transceiver technology in the subscriber terminals (ONUs). Here, the focus is on the requirements from network operators that are driving the standards developments and the technology selection prior to standardization. A prestandard view of the main physical layer optical specifications is also given, ahead of final ITU-T approval.

VCSEL-Based Interconnects for Current and Future Data Centers

Abstract: The vast majority of optical links within the data center are based on vertical cavity surface emitting lasers (VCSELs) operating at 850 nm over multimode optical fiber. Deployable links have evolved in speed from 1 Gb/s in 1996 to 28 Gb/s in 2014. Serial data links at 40 and 56 Gb/s are now under development and place even more demand on the VCSEL and photodiodes. In this paper, we present the characteristics of VCSELs and photodiodes used in current generation 28 Gb/s links and present several methods to extend link distances using more advanced data encoding schemes. Finally, we will present results on wavelength division multiplexing on multimode optical fiber that demonstrate 40 Gb/s Ethernet connections up to 300 m on duplex OM3 optical fiber, and present results on fiber optimized for modal bandwidth in the 850 to 980 nm range.

30×30 MIMO transmission over 15 spatial modes

Abstract: We transmit over all 30 spatial and polarization modes of a 22.8-km multimode fiber. 15-mode photonic lanterns enabled low-loss coupling into and out of the fiber and a time-multiplexed coherent receiver facilitates measurement of all 30 signals.

Continuous-variable quantum key distribution with 1 Mbps secure key rate

Abstract: We report the first continuous-variable quantum key distribution (CVQKD) experiment to enable the creation of 1 Mbps secure key rate over 25 km standard telecom fiber in a coarse wavelength division multiplexers (CWDM) environment. The result is achieved with two major technological advances: the use of a 1 GHz shot-noise-limited homodyne detector and the implementation of a 50 MHz clock system. The excess noise due to noise photons from local oscillator and classical data channels in CWDM is controlled effectively. We note that the experimental verification of high-bit-rate CVQKD in the multiplexing environment is a significant step closer toward large-scale deployment in fiber networks.

Coexistence of continuous variable QKD with intense DWDM classical channels

Abstract: We demonstrate experimentally the feasibility of continuous variable quantum key distribution (CV-QKD) in dense-wavelength-division multiplexing networks (DWDM), where QKD will typically have to coexist with several co-propagating (forward or backward) C-band classical channels whose launch power is around 0 dBm. We have conducted experimental tests of the coexistence of CV-QKD multiplexed with an intense classical channel, for different input powers and different DWDM wavelengths. Over a 25 km fiber, a CV-QKD operated over the 1530.12 nm channel can tolerate the noise arising from up to 11.5 dBm classical channel at 1550.12 nm in the forward direction (9.7 dBm in backward). A positive key rate (0.49 kbits s−1) can be obtained at 75 km with classical channel power of respectively −3 and −9 dBm in forward and backward. Based on these measurements, we have also simulated the excess noise and optimized channel allocation for the integration of CV-QKD in some access networks. We have, for example, shown that CV-QKD could coexist with five pairs of channels (with nominal input powers: 2 dBm forward and 1 dBm backward) over a 25 km WDM-PON network. The obtained results demonstrate the outstanding capacity of CV-QKD to coexist with classical signals of realistic intensity in optical networks.

Switching solutions for WDM-SDM optical networks

Abstract: Over the last few decades, network traffic has consistently grown at an exponential rate and was efficiently satisfied using WDM and more efficient coding schemes requiring coherent detection. There is no indication that the network traffic growth trend will cease anytime soon, and we are nearing the day when the capacity of the ubiquitous single-mode fiber will be fully exploited. Space-domain multiplexing (SDM) for high-capacity transmission is the promising solution with the scaling potential to meet future capacity demands. However, there is still a large technological gap between current WDM optical communication system designs and SDM network implementations. In this article we lay the foundation of switching node designs for future WDM-SDM optical networks.

Beyond 100-Gb/s Indoor Wide Field-of-View Optical Wireless Communications

Abstract: Optical fiber communication networks can provide terabit aggregate capacities to buildings and offices within modern cities. Practical wireless systems are orders of magnitude below this capacity. In this letter, we describe an indoor optical bidirectional wireless link with an aggregate capacity over 100 Gb/s. The link operates over ~3 m range at 224 Gb/s (6 x 37.4 Gb/s) and 112 Gb/s (3 x 37.4 Gb/s) with a wide field of view (FOV) of 60° and 36°, respectively. To the best of our knowledge, this is the first demonstration of a wireless link of this type with a FOV that offers practical room-scale coverage.

Free-space optical communications using orbital-angular-momentum multiplexing combined with MIMO-based spatial multiplexing.

Abstract: We explore the potential of combining the advantages of multiple-input multiple-output (MIMO)-based spatial multiplexing with those of orbital angular momentum (OAM) multiplexing to increase the capacity of free-space optical (FSO) communications. We experimentally demonstrate an 80 Gbit/s FSO system with a 2×2 aperture architecture, in which each transmitter aperture contains two multiplexed data-carrying OAM modes. Inter-channel crosstalk effects are minimized by the OAM beams' inherent orthogonality and by the use of 4×4 MIMO signal processing. Our experimental results show that the bit-error rates can reach below the forward error correction limit of 3.8×10(-3) and the power penalties are less than 3.6 dB for all channels after MIMO processing. This indicates that OAM and MIMO-based spatial multiplexing could be simultaneously utilized, thereby providing the potential to enhance system performance.

Mode-multiplexed transmission over conventional graded-index multimode fibers

Abstract: We present experimental results for combined mode-multiplexed and wavelength multiplexed transmission over conventional graded-index multimode fibers. We use mode-selective photonic lanterns as mode couplers to precisely excite a subset of the modes of the multimode fiber and additionally to compensate for the differential group delay between the excited modes. Spatial mode filters are added to suppress undesired higher order modes. We transmit 30-Gbaud QPSK signals over 60 WDM channels, 3 spatial modes, and 2 polarizations, reaching a distance of 310 km based on a 44.3 km long span. We also report about transmission experiments over 6 spatial modes for a 17-km single-span experiment. The results indicate that multimode fibers support scalable mode-division multiplexing approaches, where modes can be added over time if desired. Also the results indicate that mode-multiplexed transmission distance over 300 km are possible in conventional multimode fibers.

Optofluidic wavelength division multiplexing for single-virus detection

Abstract: Optical waveguides simultaneously transport light at different colors, forming the basis of fiber-optic telecommunication networks that shuttle data in dozens of spectrally separated channels. Here, we reimagine this wavelength division multiplexing (WDM) paradigm in a novel context--the differentiated detection and identification of single influenza viruses on a chip. We use a single multimode interference (MMI) waveguide to create wavelength-dependent spot patterns across the entire visible spectrum and enable multiplexed single biomolecule detection on an optofluidic chip. Each target is identified by its time-dependent fluorescence signal without the need for spectral demultiplexing upon detection. We demonstrate detection of individual fluorescently labeled virus particles of three influenza A subtypes in two implementations: labeling of each virus using three different colors and two-color combinatorial labeling. By extending combinatorial multiplexing to three or more colors, MMI-based WDM provides the multiplexing power required for differentiated clinical tests and the growing field of personalized medicine.

2.05 Peta-bit/s super-nyquist-WDM SDM transmission using 9.8-km 6-mode 19-core fiber in full C band

Abstract: We demonstrate ultra-dense SDM transmission of 360-channel Super-Nyquist-WDM DP-QPSK signals over 9.8-km 6-mode 19-core fiber, achieving the record fiber capacity of 2.05 Pbit/s (360WDM×114SDM×50Gbit/s) with the highest aggregate spectral efficiency of 456 bit/s/Hz.

Optical Peaking Enhancement in High-Speed Ring Modulators

Abstract: Ring resonator modulators (RRM) combine extreme compactness, low power consumption and wavelength division multiplexing functionality, making them a frontrunner for addressing the scalability requirements of short distance optical links. To extend data rates beyond the classically assumed bandwidth capability, we derive and experimentally verify closed form equations of the electro-optic response and asymmetric side band generation resulting from inherent transient time dynamics and leverage these to significantly improve device performance. An equivalent circuit description with a commonly used peaking amplifier model allows straightforward assessment of the effect on existing communication system architectures. A small signal analytical expression of peaking in the electro-optic response of RRMs is derived and used to extend the electro-optic bandwidth of the device above 40 GHz as well as to open eye diagrams penalized by intersymbol interference at 32, 40 and 44 Gbps. Predicted peaking and asymmetric side band generation are in excellent agreement with experiments.

A 25 Gb/s, 4.4 V-Swing, AC-Coupled Ring Modulator-Based WDM Transmitter with Wavelength Stabilization in 65 nm CMOS

Abstract: Silicon photonics devices offer promising solution to meet the growing bandwidth demands of next-generation interconnects. This paper presents a 5 × 25 Gb/s carrier-depletion microring-based wavelength-division multiplexing (WDM) transmitter in 65 nm CMOS. An AC-coupled differential driver is proposed to realize 4 × VDD output swing as well as tunable DC-biasing. The proposed transmitter incorporates 2-tap asymmetric pre-emphasis to effectively cancel the optical nonlinearity of the ring modulator. An average-power-based dynamic wavelength stabilization loop is also demonstrated to compensate for thermal induced resonant wavelength drift. At 25 Gb/s operation, each transmitter channel consumes 113.5 mW and maintains 7 dB extinction ratio with a 4.4 V $_{\rm pp-diff}$ output swing in the presence of thermal fluctuations.

Self-interference cancellation using dual-drive Mach-Zehnder modulator for in-band full-duplex radio-over-fiber system

Abstract: In this paper, we design a self-interference cancellation (SIC) scheme for in-band full-duplex (IBFD) radio-over-fiber (RoF) systems based on wavelength division multiplexing passive optical network (WDM-PON) architectures. By using a single dual-drive Mach-Zehnder modulator (DDMZM), over various bands up to 25 GHz, this proposed SIC system can simultaneously cancel the in-band downlink (DL) self-interference and modulate the recovered uplink (UL) radio frequency (RF) signal. OFDM-RF signals are used to study the cancellation performances of optical SIC system for the first time. Experimental results show more than 32-dB cancellation depth over 250-MHz bandwidth within 1-GHz RF band, as well as 300-MHz within 2.4-GHz and 400-MHz within 5-GHz band. As for 2.4-GHz RF band, 390.63-Mbps 16-QAM OFDM UL signal buried by strong in-band DL OFDM signal is well recovered. For broadband applications, more than 27-dB cancellation depth is achieved over 10 MHz~25 GHz wideband, so that up to 25 GHz RF band can be expanded for this IBFD WDM-RoF system.

Crosstalk Noise in WDM-Based Optical Networks-on-Chip: A Formal Study and Comparison

Abstract: Optical networks-on-chip (ONoCs) using wavelength-division multiplexing (WDM) technology have progressively attracted more and more attention for their use in tackling the high-power consumption and low bandwidth issues in growing metallic interconnection networks in multiprocessor systems-on-chip. However, the basic optical devices employed to construct WDM-based ONoCs are imperfect and suffer from inevitable power loss and crosstalk noise. Furthermore, when employing WDM, optical signals of various wavelengths can interfere with each other through different optical switching elements within the network, creating crosstalk noise. As a result, the crosstalk noise in large-scale WDM-based ONoCs accumulates and causes severe performance degradation, restricts the network scalability, and considerably attenuates the signal-to-noise ratio (SNR). In this paper, we systematically study and compare the worst case as well as the average crosstalk noise and SNR in three well-known optical interconnect architectures, mesh-based, folded-torus-based, and fat-tree-based ONoCs using WDM. The analytical models for the worst case and the average crosstalk noise and SNR in the different architectures are presented. Furthermore, the proposed analytical models are integrated into a newly developed crosstalk noise and loss analysis platform (CLAP) to analyze the crosstalk noise and SNR in WDM-based ONoCs of any network size using an arbitrary optical router. Utilizing CLAP, we compare the worst case as well as the average crosstalk noise and SNR in different WDM-based ONoC architectures. Furthermore, we indicate how the SNR changes in respect to variations in the number of optical wavelengths in use, the free-spectral range, and the microresonators $\boldsymbol {Q}$ factor. The analyses’ results demonstrate that the crosstalk noise is of critical concern to WDM-based ONoCs: in the worst case, the crosstalk noise power exceeds the signal power in all three WDM-based ONoC architectures, even when the number of processor cores is small, e.g., 64.

Gigabit-class optical wireless communication system at indoor distances (1.5 – 4 m)

Abstract: In this paper we experimentally realized bidirectional optical wireless communication (OWC) link using four channel visible LED board exploiting wavelength division multiplexing (WDM) for the downlink and infrared LED for uplink. We achieved greater than 5 Gbit/s data rate at common indoor distance (1.5 to 4 m) for downlink and 1.5 Gbit/s for uplink using commercially available LEDs. We achieved these results after a careful choice of the LED emission wavelengths and the optical filter spectra. Moreover, we investigate the optimal LED working current and the optimal modulation depth. The bit error ratios of all the channels were maintained lower than the FEC limit (3.8·10−3).

Demonstration of hybrid orbital angular momentum multiplexing and time-division multiplexing passive optical network.

Abstract: Mode-division multiplexing passive optical network (MDM-PON) is a promising scheme for next-generation access networks to further increase fiber transmission capacity. In this paper, we demonstrate the proof-of-concept experiment of hybrid mode-division multiplexing (MDM) and time-division multiplexing (TDM) PON architecture by exploiting orbital angular momentum (OAM) modes. Bidirectional transmissions with 2.5-Gbaud 4-level pulse amplitude modulation (PAM-4) downstream and 2-Gbaud on-off keying (OOK) upstream are demonstrated in the experiment. The observed optical signal-to-noise ratio (OSNR) penalties for downstream and upstream transmissions at a bit-error rate (BER) of 2 × 10(-3) are less than 2.0 dB and 3.0 dB, respectively.

Cascaded optical fiber link using the internet network for remote clocks comparison.

Abstract: We report a cascaded optical link of 1100 km for ultra-stable frequency distribution over an Internet fiber network. The link is composed of four spans for which the propagation noise is actively compensated. The robustness and the performance of the link are ensured by five fully automated optoelectronic stations, two of them at the link ends, and three deployed on the field and connecting the spans. This device coherently regenerates the optical signal with the heterodyne optical phase locking of a low-noise laser diode. Optical detection of the beat-note signals for the laser lock and the link noise compensation are obtained with stable and low-noise fibered optical interferometer. We show 3.5 days of continuous operation of the noise-compensated 4-span cascaded link leading to fractional frequency instability of 4x10(-16) at 1-s measurement time and 1x10(-19) at 2000 s. This cascaded link was extended to 1480-km with the same performance. This work is a significant step towards a sustainable wide area ultra-stable optical frequency distribution and comparison network at a very high level of performance.

Few-Mode Erbium-Doped Fiber Amplifiers: A Review

Abstract: Space-division multiplexing has brought a fresh perspective to the optical fiber community over the last three years and many global players around the world have been involved with both the theoretical and the experimental questions raised by this promising approach. If this technology is to be introduced in the future optical fiber networks, this implies that most of the optical components of the transmission line, including the popular Erbium-doped fiber amplifiers that lie at the heart of fiber communications need to be reexamined. This study reviews the way the new generation of Erbium-doped fibers affects the recent findings on few-mode fibers and how they may further play a central role in the deployment of this technology.

Optical wavelength demultiplexer based on photonic crystal ring resonators

Abstract: Improving transmission efficiency, quality factor, channel spacing and crosstalk levels are the top priorities in designing optical demultiplexers, suitable for wavelength division multiplexing applications. In this paper, we proposed a novel structure for designing optical demultiplexer based on photonic crystal ring resonator. For performing wavelength selection task, we used four ring resonators. The resonance wavelength of the ring resonators depends on the dimensions of the ring core; therefore, we chose two different values for the lattice constant of the ring resonators core section. The channel spacing of the structure is about 3 nm, the minimum transmission efficiency is more than 95 %, the overall quality factor is more than 2,600, and finally the crosstalk levels are better than $$-$$-19 dB.

Spectrally Efficient WDM Nyquist Pulse-Shaped 16-QAM Subcarrier Modulation Transmission With Direct Detection

Abstract: The ability to transmit signals with high information spectral density (ISD) using low-complexity and cost-effective transceivers is essential for short- and medium-haul optical communication systems Consequently, spectrally efficient direct detection transceiver-based solutions are attractive for such applications In this paper, we experimentally demonstrate the wavelength-division multiplexed (WDM) transmission of 7 $\times$ 12 GHz-spaced dispersion pre-compensated Nyquist pulse-shaped 16-QAM subcarrier modulated channels operating at a net bit rate of 24 Gb/s per channel, and achieving a net optical ISD of 20 b/s/Hz The direct detection receiver used in our experiment consisted of a single-ended photodiode and a single analog-to-digital converter The carrier-to-signal power ratio at different values of optical signal-to-noise ratio was optimized to maximize the receiver sensitivity performance The transmission experiments were carried out using a recirculating fiber loop with uncompensated standard single-mode fiber and EDFA-only amplification The maximum achieved transmission distances for single channel and WDM signals were 727 and 323 km below the bit-error ratio of ${38\times 10^{-3}}$ , respectively To the best of our knowledge, this is the highest achieved ISD for WDM transmission in direct detection links over such distances

10-Mode mode-multiplexed transmission over 125-km single-span multimode fiber

Abstract: We demonstrate combined wavelength- and mode-multiplexed transmission over a 125-km multimode single span composed of 10- and 15-mode fibers with a spectral efficiency of 29 b/s/Hz. A transmission capacity of 115.2 Tb/s is achieved over a distance of 87 km.

A comb laser-driven DWDM silicon photonic transmitter based on microring modulators.

Abstract: We demonstrate concurrent multi-channel transmission at 10 Gbps per channel of a DWDM silicon photonic transmitter. The DWDM transmitter is based on a single quantum dot comb laser and an array of microring resonator-based modulators. The resonant wavelengths of microrings are thermally tuned to align with the wavelengths provided by the comb laser. No obvious crosstalk is observed at 240 GHz channel spacing.

224-Gb/s 10-km Transmission of PDM PAM-4 at 1.3 μm Using a Single Intensity-Modulated Laser and a Direct-Detection MIMO DSP-Based Receiver

Abstract: A polarization-division-multiplexed (PDM) intensity-modulation/direct-detection (IM/DD) system enabled by a novel multiple-input and multiple-output DSP operating in the Stokes space following a DD receiver is demonstrated. Modulating the intensity of the two orthogonal polarization states of a single laser enables doubling the maximum achievable bit rate per wavelength channel, which halves the number of required laser sources in a transceiver using PDM and WDM to achieve an aggregate bit rate compared to using only WDM. Quantitatively, 224 Gb/s is experimentally transmitted over 10 km using a single 1310-nm laser and a silicon photonic intensity modulator using 56-Gbaud PDM PAM-4 with a BER of $4.1 \times 10^{-3}$ . Also, PDM enables halving the baud rate needed to achieve 112 Gb/s resulting in 20-km transmission at low BERs ( $10^{-5}\hbox{-}10^{-6}$ ), using either 56-Gbaud PAM-2 or 28-Gbaud PAM-4. These low pre-FEC BERs achieved at 112 Gb/s allow reducing the FEC overhead required compared to a single polarization system that employs twice the baud rate to achieve the same bit rate. Though the transceiver was implemented using discrete components, it can be fully integrated on a SiP chip, enabling its practical realization for short-reach optical interconnects inside datacenters. Finally, in addition to the experimental results, we perform simulations to further investigate the performance of the receiver. In particular, we studied the impact of varying the splitting ratios of the two couplers in the proposed front–end and concluded that using 67/33 couplers instead of 50/50 couplers renders the performance completely independent of the state of polarization of the received signal.

49.3 Tb/s Transmission Over 9100 km Using C+L EDFA and 54 Tb/s Transmission Over 9150 km Using Hybrid-Raman EDFA

Abstract: We review recent high capacity ultralong haul demonstrations using amplification schemes with extended C+L optical bandwidth and optimized nonlinear performance. These demonstrations achieve 49.3 Tb/s capacity over 9100 km with the use of C+L EDFAs and 54 Tb/s capacity over 9150 km using hybrid-Raman EDFAs. Using the same hybrid-Raman EDFAs, a capacity of 52.2 Tb/s over 10 230 km (534 Pb/s*km) was also demonstrated. Different combinations of three 16QAM-based coded modulation schemes with spectral efficiencies SE = 4.86, 5.4/5.45, 6.14 bit/s/Hz were used in order to maximize capacity for each amplification scheme and transmission distance. We also compare the merits of optimized transmission performance of hybrid Raman-EDFA and C+L EDFA amplification schemes based on our loop experiments. At the nonlinear limit, the use of hybrid Raman-EDFA provides a modest 9.5% increase in capacity at a cost of ∼2× higher electrical power.

Kerr Nonlinearity Mitigation: Mid-Link Spectral Inversion Versus Digital Backpropagation in 5×28-GBd PDM 16-QAM Signal Transmission

Abstract: We experimentally investigate Kerr nonlinearity mitigation of a 28-GBd polarization-multiplexed 16-QAM signal in a five-channel 50-GHz spaced wavelength-division multiplexing (WDM) system. Optical phase conjugation (OPC) employing the mid-link spectral inversion technique is implemented by using a dual-pump polarization-independent fiber-optic parametric amplifier and compared to digital backpropagation (DBP) compensation over up to 800-km in a dispersion-managed link. In the single-channel case, the use of the DBP algorithm outperformed the OPC with a Q-factor improvement of 0.9 dB after 800-km transmission. However, signal transmission was not possible with DBP in the WDM scenario over the same link length while it was enabled by the OPC with a maximum Q-factor of 8.6 dB.

Archon: A Function Programmable Optical Interconnect Architecture for Transparent Intra and Inter Data Center SDM/TDM/WDM Networking

Abstract: This paper reports all-optical, function programmable, transparent, intra- and inter-data center networking (DCN) using space and time-division multiplexing (SDM/TDM) within data centers and wavelength division multiplexing (WDM) between data centers. A multielement fiber is used for SDM transmission to provide a large quantity of optical links between the top-of-racks (ToRs) and the function programmable cluster switch. Beam-steering large-port-count fiber switches, used as central cluster switches and intercluster switch, provide a single hop optical circuit switching solution, and also enable network function programmability for DCN to support variable traffic patterns and different network functions. A TDM switch as a plug-in function provides intra-cluster communication with variable capacity and low latency. The flat-structured intra data center architecture, with a circuit-switched SDM and TDM hybrid network enables scalable, large-capacity and low-latency DCN communication. In addition, all-optical ToR-to-ToR inter-DCN is realized through metro/core networks. A highly-nonlinear fiber based all-optical SDM-to-WDM converter transfers three SDM signals to three-carrier spectral superchannel signals, which are transmitted to the destination DCN, through the metro/core networks. The all-optical ToR-ToR cross-DCN connections enable the geographically distributed DCNs to appear as one big data center.

Wavelength-Multiplexed Polymer LEDs: Towards 55 Mb/s Organic Visible Light Communications

Abstract: We present recent progress on visible light communication systems using polymer light-emitting diodes as the transmitters and a commercial silicon photodetector as the receiver In this paper, we use transmitters at red, green, and blue wavelengths to investigate the maximum on-off keying link performance of each device type as the first steps toward a wavelength-division multiplexed link We show that a total transmission speed of 13 Mb/s is achievable when considering the raw bandwidth of each of the RGB PLEDs Such a rate represents a 30% gain over previously demonstrated systems Further capacity improvement can be achieved using high performance artificial neural network equalizer offering a realistic prospect for transmission speeds up to 549 Mb/s

Transmission media for an SDM-based optical communication system

Abstract: Space-division multiplexing technology is an attractive candidate for overcoming a potential future “capacity crunch” in optical networks based on conventional single-mode fiber. Transmission media for SDM optical communication systems can be designed based on both single-and multi-core concepts. This article investigates the potential of various SDM transmission media.