A new technique for using orthogonal frequency division multiplexing (OFDM) in optical systems is presented. Clipped OFDM derived from a bipolar waveform by setting the negative values to zero. It has an efficiency 8 dB better than DC biased OFDM. If only odd subcarriers are modulated, clipping noise wanted signal.

Integrated microwave photonics, an emerging technology combining radio frequency (RF) engineering and integrated has great potential to be adopted for wideband analog processing applications.However, it been a challenge provide photonic circuits with equal levels of function flexibility as compared their electronic counterparts.Here, we introduce disruptive approach tackle this need, which is analogous field-programmable gate array.We use grid tunable Mach-Zehnder couplers interconnected in...

We show using simulations that a combination of Orthogonal Frequency Division Multiplexing (OFDM) and Optical Single Sideband Modulation (OSSB) can be used to adaptively compensate for chromatic dispersion in ultra-long-haul 10 Gbps Standard Single-Mode Fiber (S-SMF) links. Additionally, optical noise limited systems with Forward-Error Correction, OFDM tolerate an Signal Noise Ratio (OSNR) 0.5 dB higher than NRZ providing the carrier is suppressed.

We present experimental demonstrations using direct-detection and optical-orthogonal frequency division multiplexing (DD-OOFDM) for the compensation of chromatic dispersion in long-haul optical fiber links. Three transmitter designs varying electrical complexity are used single sideband (OSSB) transmission theory behind each design is discussed. The data rates achieved three systems 10, 12, 20 Gbit/s distances between 320 400 km. A discussion system overheads provided together with...

We demonstrate an RF photonic fractional Hilbert transformer based on integrated Kerr micro-comb source featuring a record low free spectral range of 48.9 GHz, yielding 75 microcomb lines across the C-band. By programming and shaping comb according to calculated tap weights, we that can achieve tunable bandwidths ranging from 1.2 15.3 switchable centre frequencies baseband 9.5 arbitrary orders. experimentally characterize amplitude phase response bandpass lowpass transformers with 90...

We show, using simulations, that a combination of orthogonal frequency division multiplexing (OFDM) and optical single sideband modulation can be used to compensate for chromatic dispersion in ultralong-haul wavelength-division multiplexed (WDM) systems. OFDM provides high spectral efficiency, does not require reverse feedback path compensation, has better sensitivity than nonreturn zero. This paper design rules 800-4000-km optical-OFDM The effects WDM channel number spacing, fiber...

Backpropagation has been shown to be the most effective method for compensating intra-channel fiber nonlinearity in long-haul optical communications systems. However, compensation is computationally expensive, as it requires numerous steps and possibly increased sampling rates compared with baud rate. This makes backpropagation difficult implement real-time. We propose: (i) low-pass filtering signal (the intensity waveform used calculate compensation) each step (ii) optimizing position of...

Simulations show orthogonal frequency division multiplexing (OFDM) with optical single sideband modulation can adaptively compensate for dispersion in 4000-km 32×10Gbps WDM SMF links 40% spectral efficiency. OFDM requires no reverse feedback path so rapid plant variations.

The nonlinear power limit of optical links using Orthogonal Frequency Division Multiplexing (OFDM) for dispersion compensation can be significantly improved an optimum combination nonlinearity precompensation and postcompensation. is implemented at the transmitter receiver as computationally-efficient power-dependent phase shifts with a single tuning parameter. system robust against exact details fiber plant's levels. Using pre post allows 2-dB increase in launch 2000-km standard single-mode...

Orthogonal frequency division multiplexing (OFDM) is used in many wired and wireless broadband communication systems because of its resilience the presence signal dispersion or multipath distortion. OFDM has not been practical optical bipolar waveform cannot be intensity-modulated direct detection (IM/DD) systems. A new unipolar form OFDM, asymmetrically clipped (ACO-OFDM), recently developed. For case an AWGN channel, we compare ACO- other modulation schemes. It shown that with 4-QAVI...

We develop a simple formula for estimating the effect of Four- Wave Mixing (FWM) on received signal quality in coherent optical systems using Orthogonal Frequency Division Multiplexing (OFDM) dispersion compensation. This shows nonlinear limit is substantially independent number OFDM subcarriers. Our analysis agrees well with full split-step Fourier method simulations, so allows multi-span to be estimated without lengthy simulations.

A versatile semiconductor laser model has been developed by the addition of a frequency-dependent gain to transmission-line modelling (TLM) method. The provides sampled optical output waveform for modulated laser, from which spectra may be found. To minimise computing time, technique sampling below frequency is introduced. theoretical basis this considered, and results gained 300 μm cavity heterojunction are compared with those given solution rate equations.

All-optical OFDM uses optical techniques to multiplex together several modulated lightsources, form a band of subcarriers that can be considered as one wavelength channel. The have frequency separation equal their modulation rate. This means they demultiplexed without any cross-talk between them, usually with Discrete Fourier Transform (DFT), implemented optically or electronically. Previous work has proposed networks couplers implement the DFT. shows topology an Arrayed Grating Waveguide...

In this paper, we use numerical simulations to show that the symbol rate has a significant effect on nonlinearity-limited performance of coherent optical communication systems. We consider case where orthogonal subcarriers are used maximize spectral efficiency. Symbol rates from 0.78125 Gbaud 100 and links up 3200 km, without inline dispersion compensation, were simulated. The results optimal for 800-km link 3200-km 6.25-Gbaud 3.125-Gbaud respectively. baud decreases as length is increased....

Abstract Integrated optical signal processors have been identified as a powerful engine for processing of microwave signals. They enable wideband and stable operations on miniaturized chips with ultimate control precision. As promising application, such enables photonic implementations reconfigurable radio frequency (RF) filters wide design flexibility, large bandwidth, high-frequency selectivity. This is key technology photonic-assisted RF front ends that opens path to overcoming the...

Asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) is a technique that sacrifices spectral efficiency in order to transmit an orthogonally multiplexed signal over unipolar channel, such as directly modulated direct-detection fiber or free-space channel. Several methods have been proposed regain this efficiency, including: asymmetrically DC-biased OFDM (ADO-OFDM), enhanced U-OFDM (EU-OFDM), and energy efficient (SEE-OFDM). This paper presents new method...

Programmable photonic integrated circuits (PICs), offering diverse signal processing functions within a single chip, are promising solutions for applications ranging from optical communications to artificial intelligence. While the scale and complexity of programmable PICs increasing, their characterization, thus calibration, becomes increasingly challenging. Here we demonstrate phase retrieval method using an on-chip fractional-delay reference path. The impulse response chip can be uniquely...

Over the last decade there has been considerable research into how artificial intelligence (AI), specifically computer vision, can assist people who are blind or have low-vision (BLV) to understand their environment. However, almost no whether tasks (object detection, image captioning, text recognition etc.) and devices (smartphones, smart-glasses investigated by researchers align with needs preferences of BLV people. We identified 646 studies published in two a half years that such...

An alternative symmetrical condensed node has been developed for which the iterative time step is independent of ratio grading on TLM mesh. The new mode fewer stubs than previous and shown to have a reduced velocity error axial propagation.

Optical Orthogonal Frequency Division Multiplexing (O-OFDM) systems use electronic digital computation to provide dispersion compensation that can be rapidly adapted changes in the optical link or network. Recent demonstrations have shown of several thousand kilometers. Earlier simulations and analysis showed better sensitivities than non-return zero systems; however, they assumed filters with very narrow bandwidths narrow-linewidth lasers. This paper explores effect filter laser linewidths...

The nonlinear power limit of optical links using orthogonal frequency division multiplexing for dispersion compensation can be significantly improved a simple and computationally efficient nonlinearity precompensation technique that requires no additional components. Simulations show 2-dB increase in transmission is possible 6 ps/nm/km fibers 4000-km system, this increases to >4 dB 2 fibers. Alternatively, the bit error ratio substantially reduced with when systems are operated at an optimum...