Coherent optical OFDM (CO-OFDM) has recently been proposed and the proof-of-concept transmission experiments have shown its extreme robustness against chromatic dispersion polarization mode dispersion. In this paper, we first review theoretical fundamentals for CO-OFDM channel model in a 2x2 MIMO-OFDM representation. We then present various design choices systems perform nonlinearity analysis RF-to-optical up-converter. also show receiver-based digital signal processing to mitigate...

Coherent optical orthogonal frequency division multiplexing is proposed to combat dispersion in media. It shown that optical-signal-to-noise ratio penalty at 10 Gbit/s maintained below 2 dB for 3000 km transmission of standard-singlemode fibre without compensation.

Coherent optical OFDM (CO-OFDM) has emerged as an attractive modulation format for the forthcoming 100 Gb/s Ethernet. However, even spectral-efficient implementation of CO-OFDM requires digital-to-analog converters (DAC) and analog-to-digital (ADC) to operate at bandwidth which may not be available today or cost-effective. In order resolve electronic bottleneck associated with DAC/ADC devices, we propose elucidate principle orthogonal-band-multiplexed (OBM-OFDM) subdivide entire spectrum...

A 1-Tb/s single-channel coherent optical OFDM (CO-OFDM) signal consisting of continuous 4,104 spectrally-overlapped subcarriers is generated using a novel device recirculating frequency shifter (RFS). The RFS produces 320.6-GHz wide spectrum single laser with superior flatness and tone-to-noise ratio (TNR). CO-OFDM comprised 36 uncorrelated orthogonal bands achieved by adjusting the delay to an integer number symbol periods. 1- Tb/s spectral efficiency 3.3 bit/s/Hz successfully received...

Phase estimation is one of the enabling functionalities in coherent optical orthogonal frequency-division-multiplexing (CO-OFDM) receivers. In this letter, we compare pilot-aided and data-aided phase methods for a CO-OFDM transmission experiment at 8 Gb/s over 1000-km standard single-mode fiber without dispersion compensation. We also show that as few five subcarriers are sufficient

There has been growing interest in coherent optical orthogonal frequency-division multiplexing (CO-OFDM). We aim to present the case that time for CO-OFDM come, terms of demand from today's ever-advancing networks and availability its underlying technologies. first lay out signal processing aspect then show a 2×2 multiple-input-multiple-output (MIMO) OFDM representation single-mode fiber channel. Through numerical simulation experimental demonstration, we further discuss various MIMO-OFDM...

The first proof-of-concept experimental demonstration of coherent optical OFDM systems is reported. 128 subcarriers with a nominal data-rate 8 Gbit/s are successfully processed and recovered after 1000 km transmission through SSMF fibre without dispersion compensation.

In coherent optical systems employing electronic digital signal processing, the fiber chromatic dispersion can be gracefully compensated in domain without resorting to techniques. Unlike compensator, equalizer enhances impairments from laser phase noise. This equalization-enhanced noise (EEPN) imposes a tighter constraint on receive for transmission with high symbol rate and large electronically-compensated dispersion.

There are three major advantages for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission using digital signal processing. First, detection is realized by phase estimation without the need phase-locked loop. Second, OFDM modulation and demodulation well-established computation-efficient fast Fourier transform (FFT) inverse FFT. Third, adaptive data rates can be supported as different quadrature amplitude (QAM) constellations software-defined, any hardware change...

There has been a trend of migration to high spectral efficiency transmission in optical fiber communications for which the frequency guard band between neighboring wavelength channels continues shrink. In this paper, we derive closed-form analytical expressions nonlinear system performance densely spaced coherent OFDM (CO-OFDM) systems. The solutions include results achievable Q factor, optimum launch power density, threshold and information limit. These clearly identify their dependence on...

Fast advancing silicon technology underpinned by Moore's law is creating a major transformation in optical fiber communications. The recent upsurge of interests orthogonal frequency-division multiplexing (OFDM) as an efficient modulation and scheme merely manifestation this unmistakable trend. Since the formulation fundamental concept OFDM Chang 1966 many landmark works others thereafter, has been triumphant almost all RF communication standards. Nevertheless, its application to...

We report successful transmission of dual-LP(11) mode (LP(11a) and LP(11b)), dual polarization coherent optical orthogonal frequency-division multiplexing (CO-OFDM) signals over two-mode fibers (TMF) using all-fiber converters. Mode converters based on mechanically induced long-period grating with better than 20 dB extinction ratios are realized used for interfacing single-mode fiber transmitter receivers to the TMF. demonstrate that by 4×4 MIMO-OFDM processing, random coupling two LP(11)...

We study the transmission performance of recently proposed multiband discrete-Fourier-transform spread orthogonal frequency-division multiplexing (MB-DFT-S-OFDM) format in which each subband is essence a single-carrier signal with Nyquist bandwidth. have found that optimal bandwidth for 428-Gb/s MB-DFT-S-OFDM 15 and 3 GHz inline dispersion compensated (IDC) nondispersion (NDC) fiber links, respectively. The optimized outperforms coherent by 1 dB (0.8 dB) after 1000-km over IDC links.

In this paper, we model and analyze the end-to-end energy consumption of 100-Gbps coherent long-haul transmission systems. particular, investigate impact forward error correction (FEC) on consumption. We compare efficiency commonly used modulation formats in transmission, namely dual polarization-quadrature phase-shift-keying (DP-QPSK) polarization-16-quadrature amplitude (DP-16-QAM), for different distance input bit rate. Our includes transmitter, booster, link amplifier as well receiver....

Few-mode fibers (FMFs) have found applications in optical communications and sensors with attractive features that standard single mode fiber (SSMF) do not possess. We report our recent progress on FMF based sensors, show the potential of utilizing spatial dimension for multi-parameter sensing discrimination capability. first a discrete type sensor interferometer structure short FMF, modal interference between either polarizations (x y) or modes (LP(01) LP(11)). then distributed by...

We demonstrate a method of LP01/LP11 dual-mode and dual-polarization coherent OFDM detection at 107 Gb/s. Successful reception is achieved over 4.5-km two-mode fiber with grating-based mode converter as mode-selective element.

Data center interconnect has stimulated the research on short-reach communications with data rate beyond 100G per wavelength and transmission distance of hundreds kilometers. Aiming at high-speed communications, we recently proposed Stokes vector direct detection (SV-DD) that realizes a linear complex optical channel similar to coherent detection. In SV-DD, transmitter places signal carrier onto orthogonal polarizations, while receiver achieves polarization insensitive 3-D in space digital...

We propose a unique few-mode fiber (FMF)-based multi-parameter optical-fiber sensor for distributed measurement of temperature and strain. launch pump probe signal through specific linearly polarized modes into FMF, monitor the Brillouin frequency shift (BFS) in each mode. By analyzing strain coefficients BFS two lowest order (LP01, LP11) modes, discrimination are successfully demonstrated, with an accuracy 1.2°C 21.9 με.

To overcome power fading induced by chromatic dispersion in optical fiber communications, field recovery is a promising solution for direct detection short-reach applications, such as fast-evolving data center interconnects (DCIs). date, various schemes capable of have been proposed, including Kramers-Kronig (KK) and signal-signal beat interference (SSBI) iterative cancellation (IC) receivers. However, they are all restricted to the single sideband (SSB) modulation format, thus conspicuously...

In this paper, we conduct theoretical and experimental study on the PMD-supported transmission with coherent optical orthogonal frequency-division multiplexing (CO-OFDM). We first present model for fiber communication channel in presence of polarization effects. It shows that can be treated as a special kind multiple-input multiple-output (MIMO) model, namely, two-input two-output (TITO) which is intrinsically represented by two-element Jones vector familiar to communications community. The...

A 1-Tb/s single-channel coherent optical OFDM (CO-OFDM) signal consisting of continuous 4104 spectrally-overlapped subcarriers is generated using a recirculating frequency shifter (RFS). Theoretical and experimental analysis the RFS performed to study its effectiveness in extending bandwidth. In particular, produces 320.6-GHz wide comb from single laser with superior flatness tone-to-noise ratio (TNR). The CO-OFDM consisted 36 uncorrelated orthogonal bands achieved by adjusting delay an...

1-Tb/s per channel coherent optical OFDM transmission over 600-km SSMF fiber is demonstrated assisted with a recirculating frequency shifter. Record spectral efficiency and reach achieved at rate without Raman amplification.

In addition to the dimensions of time, frequency, complex constellation, and polarization, spatial mode can be fifth dimension explored for modulation multiplexing in optical fiber communications. this paper, we demonstrate successful transmission 107-Gb/s dual-mode dual-polarization coherent orthogonal frequency-division (CO-OFDM) over a 4.5-km two-mode fiber. A mechanically-induced LP01/LP11 converter is used as selective element spatial-mode multiplexed system.

Intensity modulation with direct detection (IM-DD) dominates the commercial short-reach optical communications. However, when upgrading data-rate distance product to 1000 Gb/s·km per wavelength and beyond, IM-DD faces severe performance barrier. Although a linear mapping exists between intensity of transmitter receiver in back-to-back system, it becomes nonlinear under fiber channel impairments; for instance, dominant chromatic dispersion. Coherent overcomes this fundamental obstacle by...