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»

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»

In this paper, we implement an optical fiber communication system as an end-to-end deep neural network, including the complete chain of transmitter, channel model, and receiver. This approach enables the optimization of the transceiver in a single end-to-end process. We illustrate the benefits of this method by applying it to intensity modulation/direct detection (IM/DD) systems and show that we c... View full abstract»

We present the demonstration of an integrated frequency modulated continuous wave LiDAR on a silicon platform. The waveform calibration, the scanning system, and the balanced detectors are implemented on a chip. Detection and ranging of a moving hard target at upto 60 m with less than 5 mW of output power is demonstrated in this paper. 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 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»

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»

Next generation 5G mobile system will support the vision of connecting all devices that benefit from a connection, and support a wide range of services. Consequently, 5G transport networks need to provide the required capacity, latency, and flexibility in order to integrate the different technology domains of radio, transport, and cloud. This paper outlines the main challenges, which the 5G transp... View full abstract»

After dominating the electronics industry for decades, silicon is on the verge of becoming the material of choice for the photonics industry: the traditional stronghold of III-V semiconductors. Stimulated by a series of recent breakthroughs and propelled by increasing investments by governments and the private sector, silicon photonics is now the most active discipline within the field of integrat... View full abstract»

We achieved the lowest-ever transmission losses of 0.1419 dB/km at 1560 nm wavelength and 0.1424 dB/km at 1550 nm in a Ge-free silica-core optical fiber. It was an improvement by 4 mdB/km from the previous record realized in 2015. The Ge-free silica core included fluorine co-doping, which helps to reduce disorder in the microscopic glass network structure that causes Rayleigh scattering loss witho... 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»

Microwave measurement refers to the acquisition of parameters of a microwave signal or the identification of properties of an object via microwave-based approaches. Thanks to the broad bandwidth and high speed provided by modern photonics, microwave measurement in the optical domain can provide better performance in terms of bandwidth and speed which may not be achievable using traditional, even s... 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»

Optical transmitter and receiver ICs, each with a footprint of 25 mm2, were fabricated using a silicon photonics platform based on 40-nm-node CMOS technology. High-speed transmissions of data at 300 Gbps were demonstrated. The wire-type waveguide (WG) in the transmitter IC had a width of 350 nm and a height of 200 nm, and in the completed optical IC, it showed low propagation loss (1.62... 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 relat... 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»

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»

RF channelization is regarded as one of the most effective approaches to relieve the difficulty of processing wideband signals in microwave and millimeter-wave receivers. In this paper, a novel coherent optical RF channelizer with broad instantaneous bandwidth and large in-band interference suppression is proposed and demonstrated based on a multichannel photonic image-reject mixer (IRM). A Ku-ban... 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»

To realize cost-effective and adaptive network control and management (NC&M) on inter-datacenter optical networks (IDCONs), people have considered network virtualization to let the operator of an IDCON work as an infrastructure provider (InP), which can create virtual optical networks (VONs) over the IDCON for tenants. In this paper, we use this network scenario as the background, and try to i... View full abstract»

This paper proposes and experimentally demonstrates, for the first time, two new candidate pulse shapes for carrierless amplitude and phase modulation in the context of visible light communications. It is commonly accepted that the pulse shape at the heart of the Hilbert pair used to generate the required orthogonal signal spaces should be the square-root raised cosine. In this paper, we introduce... 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 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»

The optoelectronic oscillator (OEO) has attracted a great deal of attention in recent years as a high-performance microwave source. Thanks to the high quality-factor (Q-factor) provided by the optical delay line, the OEO can generate spectrally pure microwave signals with ultralow phase noise. Various approaches for realization of OEO architectures for the generation of single-frequency microwave ... 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»

We study the techno-economics of submarine systems constrained by a fixed electrical power supply. We show significant cost savings for high-capacity submarine systems using massive space-division multiplexing (SDM), even without assuming any savings from SDM-specific subsystem integration. Systems with about 100 parallel optical paths, e.g., ~50 fiber pairs are shown to provide minimum cost/bit, ... View full abstract»

The performance of unrepeatered transmission of a seven Nyquist-spaced 10 GBd PDM-16QAM superchannel using full signal band coherent detection and multi-channel digital back propagation (MC-DBP) to mitigate nonlinear effects is analysed. For the first time in unrepeatered transmission, the performance of two amplification systems is investigated and directly compared in terms of achievable informa... View full abstract»

Microwave photonic filters are photonic subsystems designed with the aim of carrying equivalent tasks to those of an ordinary microwave filter within a radio frequency (RF) system or link, bringing supplementary advantages inherent to photonics such as low loss, high bandwidth, immunity to electromagnetic interference (EMI), tunability, and reconfigurability. There is an increasing interest in thi... View full abstract»

In this paper, we introduce an end-to-end and real-time seamless fiber-wireless (Fi-Wi) bridge system, for gigabit Ethernet standard data connectivity and 8K standard video streaming. The proposed end-to-end Fi-Wi bridge system consists of seamless integration of 2 × 20-km intermediate frequency-over-fiber (IFoF) and 96-GHz millimeter-wave (mmWave) wireless links. Using our system, zero packet los... View full abstract»

A $4 \times 4$ silicon photonic switch based on a voltage-driven Mach-Zehnder interferometer (MZi) was modeled using transfer matrices, whose parameters were determined by fitting smoothed, wavelength-resolved transmission measurements. The model is constructed using voltages that configure each MZi in an intermediate (quadrature point) switch setting. This state is not used during normal operatio... View full abstract»

We investigate the performance and design of free-space optical (FSO) communication links over slow fading channels from an information theory perspective. A statistical model for the optical intensity fluctuation at the receiver due to the combined effects of atmospheric turbulence and pointing errors is derived. Unlike earlier work, our model considers the effect of beam width, detector size, an... View full abstract»

The two-dimensional graphene has an extremely high carrier mobility that can potentially offer an electrical bandwidth of over 500 GHz. However, the bandwidth of the reported graphene-based modulators is only a few tens of gigahertz due to the limitation of the RC constant rather than the carrier transit time. In this paper, a high-speed traveling-wave electro-optic modulator based on a graphene/m... View full abstract»

Different aspects of probabilistic shaping for a multispan optical communication system are studied. First, a numerical analysis of the additive white Gaussian noise (AWGN) channel investigates the effect of using a small number of input probability mass functions (PMFs) for a range of signal-to-noise ratios (SNRs), instead of optimizing the constellation shaping for each SNR. It is shown that if ... View full abstract»

We report a broadband RF channelizer based on an integrated optical frequency Kerr micro-comb source, with an RF channelizing bandwidth of 90 GHz, a high RF spectral slice resolution of 1.04 GHz, and experimentally verify the RF performance up to 19 GHz. This approach of realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave sign... View full abstract»

Nowadays, the microwave photonics (MWP) concept has been evolved from laboratory tests to practical applications, and related techniques have been widely deployed in many fields including such as wireless communications, medicine, sensing, radars, electronic warfare, and space explorations. In this paper, we concentrate on the featured applications of MWP in the high-speed railways (HSRs), an emer... 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 present the first demonstration of a wireless transmission link based on uni-traveling carrier photodiodes (UTC-PDs) as transmitter and receiver. In this demonstration, a UTC-PD was used at the transmitter to generate a 1-Gbps on-off keying data signal at a carrier frequency of 61.3 GHz by heterodyning two modulated optical tones originating from an optical frequency comb system. The generated ... 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»

Electron-beam lithography allows precise photonic crystal (PC) fabrication, but is not suitable for mass production. Therefore, the development and optimization of CMOS-compatible processes is necessary to implement unique nanocavity technologies in optoelectronic circuits. We investigated the quality factors (Q) and the resonant wavelengths (λ) of PC heterostructure nanocavities fabricated by the... View full abstract»

The optical transport network (OTN) protocol defined by the ITU-T (Recommendation G.709) has become the backbone of service provider long haul and metro networks. Its flexibility has allowed it to support the converged transparent transport for the full variety of both constant bit rate and packet-oriented digital WAN client signals, and its overhead is optimized to reduce the equipment and operat... View full abstract»

We consider a nonlinear Fourier transform (NFT) based transmission scheme, where data are embedded into the imaginary part of the nonlinear discrete spectrum. Inspired by probabilistic amplitude shaping, we propose a probabilistic eigenvalue shaping (PES) scheme as a means to increase the data rate of the system. We exploit the fact that for an NFT-based transmission scheme, the pulses in the time... View full abstract»

Photonic generation of a frequency-tunable microwave signal based on a silicon photonic integrated optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The silicon photonic chip includes a high-speed phase modulator (PM), a thermally tunable micro-disk resonator (MDR), and a high-speed photodetector (PD). When an external light wave is injected into the chip, by a joint use... View full 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 ... View full abstract»

We report simultaneous transmission of six spatial and polarization modes, each carrying 40 Gb/s quadrature-phase-shift-keyed channels over 96 km of a low-differential group delay few-mode fiber. The channels are successfully recovered by offline DSP based on coherent detection and multiple-input multiple-output processing. A penalty of <;1.2 dB is achieved by using 6 × 6 feed-forward equalizer... 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»

We propose to generate excitatory and inhibitory neuron-like dynamics in vertical-cavity surface-emitting lasers (VCSELs) by applying simultaneously the orthogonally-polarized CW optical injection (OPCWOI) and parallelly-polarized pulse optical injection stimulus. Based on the spin flip model, excitatory and inhibitory neuron-like dynamics accompanying with reverse polarization switching is numeri... 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 density of 2.... 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»

The growing traffic demand in interdata center and metro communications requires high-speed and low-cost transceivers that can flexibly adapt to different transmission distances of up to a few hundred km. Ultimately low-cost transceivers will use the simplest optical hardware, namely a directly modulated transmitter and direct detection receiver. Using optical injection-locked directly modulated l... View full abstract»

Polarization converter is firstly proposed with the functions of simultaneously converting a linear polarization (LP) and a circular polarization (CP) to its corresponding cross polarizations, and polarization conversion ratio (PCR) of the converter with graphene strips is also controllable in this paper. A reflectiontype converter is designed based on a metasurface in the terahertz region. It con... View full abstract»