Journal of Lightwave Technology

The recently developed digital coherent receiver enables us to employ a variety of spectrally efficient modulation formats such as M-ary phase-shift keying and quadrature-amplitude modulation. Moreover, in the digital domain, we can equalize all linear transmission impairments such as group-velocity dispersion and polarization-mode dispersion of transmission fibers, because coherent detection pres... View full abstract»

Internet of Things (IoT) requires cloud infrastructures for data analysis (e.g., temperature monitoring, energy consumption measurement, etc.). Traditionally, cloud services have been implemented in large datacenters in the core network. Core cloud offers high-computational capacity with moderate response time, meeting the requirements of centralized services with low-delay demands. However, colle... View full abstract»

This paper attempts to clarify the difference between visible light communication (VLC) and light-fidelity (LiFi). In particular, it will show how LiFi takes VLC further by using light emitting diodes (LEDs) to realise fully networked wireless systems. Synergies are harnessed as luminaries become LiFi attocells resulting in enhanced wireless capacity providing the necessary connectivity to realise... View full 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. Innovat... View full abstract»

Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives... View full abstract»

This paper aims to address the perception that visible light communication (VLC) systems cannot work under the presence of sunlight. A complete framework is presented to evaluate the performance of VLC systems in the presence of solar irradiance at any given location and time. The effect of solar irradiance is investigated in terms of degradations in signal to noise ratio, data rate, and bit error... View full abstract»

For a future 5G Ethernet-based fronthaul architecture, 100G trunk lines of a transmission distance up to 10 km over a standard single-mode fiber (SSMF) in combination with cheap gray optics to daisy chain cell site network interfaces are a promising cost- and power-efficient solution. For such a scenario, different intensity modulation and direct detect formats at a data rate of 112 Gb/s, namely N... View full abstract»

Machine learning techniques relevant for nonlinearity mitigation, carrier recovery, and nanoscale device characterization are reviewed and employed. Markov Chain Monte Carlo in combination with Bayesian filtering is employed within the nonlinear state-space framework and demonstrated for parameter estimation. It is shown that the time-varying effects of cross-phase modulation (XPM) induced polariz... View full abstract»

Broadband and low loss capability of photonics has led to an ever-increasing interest in its use for the generation, processing, control and distribution of microwave and millimeter-wave signals for applications such as broadband wireless access networks, sensor networks, radar, satellite communitarians, instrumentation and warfare systems. In this tutorial, techniques developed in the last few ye... View full abstract»

Four-level pulse amplitude modulation (PAM-4) is widely regarded as the modulation format of choice for the next generation of 400 gigabit Ethernet short-reach optical transceiver. However, generating and receiving PAM-4 at line rates of 112 Gb/s has proven challenging, without relying on power-hungry tools as digital signal processing and digital-to-analog converters, as it requires linearity fro... View full abstract»

We describe a method to estimate the capacity limit of fiber-optic communication systems (or ¿¿fiber channels¿¿) based on information theory. This paper is divided into two parts. Part 1 reviews fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit rel... View full abstract»

The fifth generation (5G) wireless technology is designed to provide significantly faster Internet access, with lower latency, and ubiquitous mobile coverage compared to its predecessors. However, as there will be hundreds and thousands of wireless cells deployed in the 5G network, transporting the enormous volume of data instigated from high capacity 5G wireless cells to the core network in a cos... View full abstract»

Indoor wireless traffic is evolving at a staggering pace, and is quickly depleting radio spectrum resources. Optical wireless communication (OWC) offers powerful solutions for resolving this imminent capacity crunch of radio-based wireless networks. OWC is not intended to fully replace radio wireless techniques such as WiFi, but to complement these and offload their high traffic loads. After discu... View full abstract»

Multicore fibers (MCFs) are expected as a good candidate for overcoming the capacity limit of a current optical communication system. This paper describes the recent progress on the MCFs for space-division multiplexing to be utilized in future large capacity long-distance transmission systems. Tradeoff issue between low crosstalk and high core density in MCFs is presented and prospect of large-spa... View full abstract»

The historical beginnings of photosensitivity and fiber Bragg grating (FBG) technology are recounted. The basic techniques for fiber grating fabrication, their characteristics, and the fundamental properties of fiber gratings are described. The many applications of fiber grating technology are tabulated, and some selected applications are briefly described View full abstract»

In multiple-input multiple-output (MIMO) indoor visible light communication (VLC) systems, the elements of the channel matrix can be highly correlated which is a cause for degraded bit error performance. Imaging receiver techniques can resolve the spatial correlation in VLC channels because of the increased spatial resolution possible in imaging receivers. In this paper, we investigate the perform... View full abstract»

A highly power-efficient silicon (Si) photonic PAM4 transmitter was developed by integrating a Si segmented Mach- Zehnder modulator and a CMOS driver chip. Si p-i-n-type phase shifters are directly driven with a CMOS inverter driver array to realize a low power operation. A passive RC equalizing technique was adopted to extend the modulation bandwidth up to 20 GHz while maintaining a low power con... View full abstract»

Due to their simple and cost-effective transceiver architecture, single-polarization and single-photodiode-based direct-detection (DD) systems offer advantages for metropolitan area network and data-center interconnect applications. Single-sideband subcarrier modulation (SSB SCM) signaling with DD has the potential to achieve high information spectral density (ISD) but its performance can be signi... View full abstract»

We investigate the feasibility of implementing a mobile fronthaul network (MFN) based on the radio-over-fiber (RoF) technology for the 5th generation wireless communication systems cost-effectively by using either directly modulated laser (DMLs) or electro-absorption modulated lasers (EMLs) operating in the 1.55-μm window. The results show that the performance of the RoF-based MFN implement... View full abstract»

The next-generation passive optical network stage 2 (NG-PON2) effort was initiated by the full service access network (FSAN) in 2011 to investigate on upcoming technologies enabling a bandwidth increase beyond 10 Gb/s in the optical access network. The FSAN meeting in April 2012 selected the time- and wavelength-division multiplexed passive optical network (TWDM-PON) as a primary solution to NG-PO... View full abstract»

In general, visible light communication (VLC) systems, which utilise white light-emitting diodes (LEDs), only offer a bandwidth limited to the lower MHz region. Therefore, providing VLC-based high data rate communications systems using VLC becomes a challenging task. To address this challenge, we propose a solution based on multiplexing in both the frequency and space domains. We experimentally de... View full abstract»

In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, d... View full abstract»

Space-division multiplexing (SDM) is an attractive technique for dramatically enhancing the transmission capacity in a single optical fiber. Recently, ultradense SDM transmission experiments with a spatial multiplicity of over 100 have been reported by using few mode multicore fibers (FM-MCFs). Considering the maximum capacity of around 100 Tb/s reported in single-mode single-core fiber transmissi... View full abstract»

Since energy dissipation and latency in optical interconnects are of utmost concern, such links are often operated without forward error correction. We propose a low-complexity noniterative two-error correcting Bose-Chaudhuri-Hocquenghem (BCH) decoder circuit that significantly relaxes the stringent optical modulation amplitude requirements on the transmitter, which help to reduce laser and laser ... View full abstract»

In this paper, three forms of orthogonal frequency division multiplexing (OFDM) designed for intensity modulated/direct detection (IM/DD) optical systems are compared. These are asymmetrically clipped optical OFDM (ACO-OFDM), DC biased optical OFDM (DCO-OFDM) and asymmetrically clipped DC biased optical OFDM (ADO-OFDM). ADO-OFDM is a new technique that combines aspects of ACO-OFDM and DCO-OFDM by ... View full abstract»

This paper presents an overview of integrated optics routing and coupling devices based on multimode interference. The underlying self-imaging principle in multimode waveguides is described using a guided mode propagation analysis. Special issues concerning the design and operation of multimode interference devices are discussed, followed by a survey of reported applications. It is shown that mult... View full abstract»

We describe the advances that we, and others, have reported during the last years in the area of programmable microwave photonic processors. Following a brief historical sketch, we provide a detailed account of the salient theoretical and experimental results recently reported on waveguide mesh optical core processors. The incorporation of a waveguide mesh optical core into the general microwave p... View full abstract»

A high-efficiency grating fabrication method was, for the first time, demonstrated to inscribe helical long period fiber gratings (H-LPFGs) in small numbers by means of twisting a standard single-mode fiber (SMF) during hydrogen-oxygen flame heating and then cutting the helical fiber into in series of sections. Each section of the helical fiber was a desired LPFG whose resonant wavelength, i.e., g... View full abstract»

Visible light communications is an alternative method of indoor wireless communications that requires sensitive receivers. Ideally, single photon avalanche detectors (SPADs) could be used to create more sensitive receivers. However, the dead time, finite output pulse width, and photon detection efficiency of existing SPAD arrays limit their sensitivity and bandwidth. In this paper, an accurate equ... View full abstract»

The performance of direct-detection transceivers employing electronic dispersion compensation combined with DSP-based receiver linearization techniques is assessed through experiments on a 4 × 112 Gb/s wavelength-division multiplexing direct-detection single-sideband 16 quadratic-amplitude modulation Nyquist-subcarrier-modulation system operating at a net optical information spectral densit... View full abstract»

A novel hybrid multiplexer for wavelength-division- multiplexing (WDM) and polarization-division-multiplexing (PDM) is proposed and realized by integrating a polarization-splitter-rotator (PSR) and an optical-filter array based on novel microring resonators (MRRs). With the PSR, the launched TM-polarized light is rotated to be TE-polarized and outputs from the cross port while the launched TE-pola... View full abstract»

Light-fidelity (LiFi) relies on visible light communication to provide multiuser access in a small cell. For higher throughput, this paper studies the resource allocation problem for an orthogonal frequency-division multiplexing access scheme for LiFi downlink transmissions and presents a joint design of the bias level, power and subcarrier allocation. Decomposing the original optimization into su... View full abstract»

Fiber-induced intra- and interchannel nonlinearities are experimentally tackled using blind nonlinear equalization (NLE) by unsupervised machine-learning-based clustering (MLC) in ~46-Gb/s single-channel and ~20-Gb/s (middle-channel) multichannel coherent multicarrier signals (orthogonal frequency-division multiplexing (OFDM) based). To that end, we introduce, for the first time, hierarchical and ... View full abstract»

A high-sensitivity Fabry-Perot interferometer (FPI) strain sensor based on a concave-core photonic crystal fiber (CPCF) was proposed and demonstrated. The FPI was formed by directly splicing a CPCF to a standard single-mode fiber. The CPCF was fabricated by cleaving a high-numerical-aperture solid-core photonic crystal fiber under axial tension using a traditional fiber cleaver. An FPI strain sens... View full abstract»

Multi-wavelength (MW) laser sources with high optical signal-to-noise ratios (OSNR) are of great interest for optical communications with ultrahigh data capacity as well as microwave and terahertz photonics. In this paper, we report the first demonstration of MW Brillouin random fiber laser in the telecom spectral window around 1.5 μm based on a unique random fiber grating (RFG). Random fee... View full abstract»

Space-division multiplexing (SDM) has been intensively proposed in recent years to overcome the capacity limitations of the current single-mode fiber infrastructure and to increase the efficiency of optical transmission systems. Few-mode fibers offer the potential of transmitting several signals at the same wavelength over different modes of a fiber with one single core. In this paper, we demonstr... View full abstract»

We demonstrated a support vector machine (SVM) based machine learning method to mitigate modulation nonlinearity distortion for PAM-4 and PAM-8 vertical cavity surface emitter laser multi-mode fiber (VCSEL-MMF) optical link. Simulations at 100 Gb/s data rate and experimental work at 60 Gb/s data rate were carried out. We achieved a significant improvement in bit error rate (BER) when complete bina... View full abstract»

Potential niches for a power-over-fiber (PoF) technique can be found in hazardous areas that require controlling unauthorized access to risk areas and integration of multiple sensors, in scenarios avoiding electromagnetic interference, and the presence of ignition factors. This paper develops a PoF system that provides galvanic isolation between two ends of a fiber for remotely powering a proximit... View full abstract»

We investigate the resonance property of a self-coupled optical waveguide (SCOW) with four coupling points. Under a special condition that the two outer couplers are in weak coupling and the two inner couplers are in strong coupling, an implicit standing-wave resonance mode is formed inside the SCOW structure. As the resonance is feedback coupled via an S-shape bus waveguide, electromagnetically i... View full abstract»

Following on from current 1 Gb/s to 10 Gb/s based passive optical networks (PON), IEEE 802.3ca has commenced discussion of the first 100 Gb/s-based PON standard in the form of 100 G Ethernet PON (100G-EPON), in anticipation of growing bandwidth demand by emerging applications such as fixed-mobile convergence for 5G and beyond 5G (B5G) where mobile front-haul and mobile back-haul (MFH/MBF) will req... View full abstract»

A compact polarization beam splitter (PBS) is presented for the case with a 340-nm-thick silicon core layer by using an asymmetric evanescent coupling system. It consists of a narrow input waveguide, a narrow output waveguide, and a wide middle waveguide between them. In this design, the widths of these three waveguides are chosen optimally, so that the phase matching condition is satisfied for th... View full abstract»

Analogs of Electromagnetically Induced Transparency (EIT) in metamaterial have undoubtedly become a research hotspot in recent years. In this paper, we summarized some of the literature on EIT published to date and compared their performance. Then, we designed two kinds of metamaterials using aluminum and silicon. Both have the similar glasses-shaped structure of a periodic lattice with one bar re... View full abstract»

Structural Health Monitoring (SHM) can be understood as the integration of sensing and intelligence to enable the structure loading and damage-provoking conditions to be recorded, analyzed, localized, and predicted in such a way that nondestructive testing becomes an integral part of them. In addition, SHM systems can include actuation devices to take proper reaction or correction actions. SHM sen... View full abstract»

We successfully developed a high-density broadband 16-channel × 25 Gb/s on-package silicon photonics optical transceiver. The flip chip bonded bridge structure realized high density of about 363 Gb/s/cm² . We demonstrated simultaneously on all 16 channels error-free operations with low crosstalk penalties of Tx-to-Tx 1.4 dB, Rx-to-Rx 1.4 dB, and Tx-to-Rx <;0.1 dB. View full abstract»

We discuss and propose millimeter-wave linear cell systems for signal distribution on railway radiocommunication systems between train and trackside, and a foreign object debris detection system for airport runways using the radio-over-fiber network technology. Linear cell configurations based on wavelength-division multiplexing (WDM) and power-splitter-based distribution networks are discussed an... View full abstract»

This paper compares methods of active stabilization of an optoelectronic microwave oscillator (OEO) based on insertion of a source of optical group delay into an OEO loop. The performance of an OEO stabilized with either a high-Q optical cavity or an atomic cell is analyzed. We show that the elements play a role of narrow-band microwave filters improving an OEO stability. An atomic cell also allow... View full abstract»

Erbium-doped fiber amplifiers are modeled using the propagation and rate equations of a homogeneous two-level laser medium. Numerical methods are used to analyze the effects of optical modes and erbium confinement on amplifier performance, and to calculate both the gain and amplified spontaneous emission (ASE) spectra. Fibers with confined erbium doping are completely characterized from easily mea... View full abstract»

We transmit 51.5 Tb/s capacity over 17,107 km with C+L band erbium doped fiber amplifiers (EDFAs) and demonstrate a record single mode fiber capacity-distance product of 881 Pb/s × km. This is achieved by using a performance optimized multidimensional coded modulation format with hybrid probabilistic and geometric constellation shaping. This 4D-PS-7/12-40APSK modulation format is designed t... View full 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 an... View full abstract»

A spider uses up to seven different types of silk, all having specific functions, as building material, weapon, and sensory organ to detect the presence of preys on its web. Recently, scientists have put under the limelight the extraordinary properties of this ancient material. Indeed, native silk, directly extracted from spiders, is a tough, biodegradable, and biocompatible thread used mainly for... View full abstract»