Fiber Bandwidth Research Articles

Relative intensity noise management and thermal/shot noise control for high speed ultra high bandwidth fiber reach transmission performance

Abstract This work has clarified the relative intensity noise management and thermal/shot noise control for high speed ultra high bandwidth fiber reach transmission performance. Total link losses variations are clarified against ambient temperature and relative refractive index difference variations at 1,550 nm wavelength, 20 km fiber link length, and 45 % fluoride dopant ratio inside the fiber material cable. Besides the total link losses variations are demonstrated versus fiber link length and relative refractive index difference variations at 1,550 nm wavelength, room temperature, and 45 % fluoride dopant ratio inside the fiber material cable. Required optical signal per noise ratio (OSNR), electronic signal to noise ratio (SNR), and optimum gain variations are measured and analyzed versus the fiber link length and relative refractive index difference variations at 1,550 nm wavelength, room temperature, and 45 % fluoride dopant ratio inside the fiber material cable.

Various graded index plastic optical fiber performance signature capability with the optimum dispersion control for indoor coverage applications

Abstract This work has clarified the various graded index plastic optical fiber performance signature with the optimum dispersion control for indoor coverage applications. The plastic optical fibers that are deeply employed namely Polymethyl mathacrylate (PMMA), Epoxy, Polyfluorene and Cyclotene. Various plastic optical fiber dispersion is demonstrated against temperature variations. The different plastic fibers pulse broadening is clarified versus temperature variations. The previous plastic optical fibers types with respect to refractive index configuration and number of modes are clarified. Previous studies on PMMA/CYTOP plastic optical fibers attenuation is clarified against wavelength band variations. Various transmission techniques are applied to measure the fiber bandwidth and fiber channel bit rate. These transmission techniques are MTDM, NRZ and RZ coding. Different plastic fiber bandwidth against fiber channel distance is demonstrated based on NRZ, RZ and MTDM coding at room temperature. Different plastic fiber channel bit rate against fiber channel distance is studied and clarified based on NRZ, RZ and MTDM coding at room temperature. The choice of these plastic fibers are high temperature stability and more flexibility/reliability than other plastic fibers. The dispersion of these proposed plastic fibers can be controlled and managed with the control of temperature variations.

Comparative study of single pump all optical fiber amplifiers (POAs) with ultra wide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers

Abstract This paper has clarified comparative study of single pump all optical fiber amplifiers with ultrawide band and high gain fiber optic parametric amplifiers in highly nonlinear fibers. Different amplifiers gain is demonstrated versus system distance for different light amplifiers in highly nonlinear fiber channel. As well as amplifier gain is clarified against system distance for different light amplifiers in DCF, DSF and NZDSF fiber channel. The mechanism of generation of single idler signal is studied based on single signal and pump signal. Moreover the mechanism of generation of single idler signal is analyzed and investigated clearly based on signal and two pump signals. Amplifier bandwidth is demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. The map of the signal losses is discussed and clarified versus wavelength band in the presence of all amplification techniques. Light signal per noise ratio and bit error rates are demonstrated against system distance for different fiber channel types in the presence of POA amplifiers based on 100 mW, 300 mW and 500 mW pumping power. POA is more suitable for the operation in HNLF fiber channel in compared to other proposed fiber communication channels. All optical amplifiers operation performance gain efficiency is compared together in different fiber channel media. The system can be employed with POAs for the fiber reach up to 100 km distance with a suitable amplifier gain and bandwidth. An important criteria for any amplifier is its gain and bandwidth for the compensation of the system loss and dispersion together. The optimum suitable pumping power is clarified for upgrade the system amplifier performance signature.

Application of the power flow equation in modeling bandwidth in polymer optical fibers: a review

Application of the power flow equation in modeling bandwidth in polymer optical fibers: a review

Design method of variable slippage coefficient non‐geodesic filament‐wound composite pressure vessels

AbstractPrevious studies on the design methods of filament winding paths for composite pressure vessels have mainly focused on geodesic and constant slippage coefficient non‐geodesic patterns, neglecting the design of variable slippage coefficients along the fiber path. In this paper, a design method of variable slippage coefficient non‐geodesic filament wound composite pressure vessels is proposed. The study begins by establishing a meridian rotation mapping model and deriving fiber path equations on the shell surface. Subsequently, the fiber paths, curvature characteristics, slippage coefficients, and shell stress responses of the shell under variable geometrical parameters are simulated and analyzed. Next, the winding parameters are optimized while considering bandwidth and stable winding constraints. The optimal winding parameters are determined, and filament winding simulations are conducted on composite pressure vessels. Results demonstrate the feasibility of the proposed method for variable slippage coefficient fiber path winding mode, providing a new and effective filament winding path design approach for composite pressure vessels.Highlights Establishment of meridian rotation mapping model and simulation of shell fiber paths under variable geometric parameters. The fiber paths, curvature characteristics, slippage coefficients, and winding angles of the shell under variable geometrical parameters are simulated and analyzed. Stress response analysis of shells based on Tsai‐Wu failure criterion and classical lamination theory stress field dimensionless modeling. Construction of winding parameter optimization strategies and bandwidth error evaluation based on stable winding and fiber bandwidth constraints. Simulation of variable slippage coefficient non‐geodesic filament winding for composite pressure vessels with different parameters.

Modeling of neodymium-doped wideband fiber amplifier gain spectrum and numerical simulation optimization based on Matlab genetic algorithm: 1300-1400 nm peak gain maximization

The gain spectrum of the neodymium-doped wideband fiber amplifier was modeled and simulated by Matlab, and the intelligent optimization algorithm (genetic algorithm) included in Matlab was used to optimize the fiber length and doping concentration to maximize the peak gain (find the optimal fiber length and doping concentration within the set range). According to the set signal optical wavelength range (1300 nm~1400 nm) and the corresponding neodymium ions four-level transition structure, the pump optical wavelength (800 nm) is designed and the four-level structure rate equation and power propagation equation are established, and Matlab programming calculates the change of gain with fiber length, neodymium ions doping concentration and pump optical power. According to the obtained gain curve, it can be inferred that under the parameter range set in this study, the gain of the neodymium-doped fiber amplifier increases significantly with fiber length and neodymium ions doping concentration, while the pump optical power has almost no effect on the gain value.

Artificial Neural Network Assisted Probabilistic and Geometric Shaping for Flexible Rate High-Speed PONs

In this paper, we employ artificial neural networks (ANNs) to optimize joint probabilistic shaping (PS) and geometric shaping (GS) for a realistic 50G IM/DD passive optical network (PON) link. Apart from being able to find a generalized mutual information (GMI)-maximizing modulation for channel conditions unseen at the training phase, the compatibility of the ANN training with Monte Carlo simulation also enables us to use a more complicated channel model that more closely resembles a real PON system where fiber dispersion, bandwidth limitation and digital signal processing (DSP) are present. The forward error correction (FEC) requirement that must be satisfied in an actual implementation is imposed on the learned modulation by including a normalized GMI (NGMI) penalty term in the loss function. The proposed scheme is demonstrated with simulations. Results show that the ANN can achieve similar performance compared to a case-by-case optimization while also being capable of generalizing to a wide range of received optical power (ROP) from −30 dBm to −18 dBm and/or a broad range of fiber distance from 0 km to 20 km. About 0.1-bits/symbol GMI improvement is attained compared to uniform modulation.

A Broadband Optical Fiber Coupler Based on Dual-Hollow Core Fiber

Hollow fiber has become a research hotspot in the field of special fibers for its excellent characteristics, such as low loss, low delay, low dispersion, and low nonlinear coefficient. Due to the lack of fiber coupler matching hollow core fiber, the application development of hollow core fiber in the all-fiber integrated system is greatly hindered. Dual-core fiber is widely used in the development of fiber couplers because it can choose optical power, wavelength, and polarization state by the coupling between the two cores. For the urgent need for hollow core fiber coupler, the design and research of wideband fiber coupler based on dual-hollow core fiber are carried out in this paper. Based on the coupled mode theory, the theoretical correlation between the structural parameters and the coupling length in the dual-hollow core anti-resonant fiber was analyzed by using the COMSOL simulation software system. On this basis, a 50:50 wideband fiber coupler was designed by adjusting the structural parameters to reduce the coupling length and introducing the sleeve into the cladding pipe to reduce the loss. The bandwidth of the coupler is up to 150 nm and the transmission loss is on the order of 10−2 dB/m.

Reflective optical vortex generators with ultrabroadband self-phase compensation

The explosive growth of information urgently requires extending the capacity of optical communication and information processing. Orbital-angular-momentum-based mode division multiplexing (MDM) is recognized as the most promising technique to improve the bandwidth of a single fiber. To make it compatible with the dominant wavelength division multiplexing (WDM), broadband equal high-efficient phase encoding is highly pursued. Here, we propose a twisted-liquid-crystal and rear-mirror-based design for ultrabroadband reflective planar optics. The backtracking of the light inside the twisted birefringent medium leads to an achromatic phase modulation. With this design, a single-twisted reflective q-plate is demonstrated to convert a white beam to a polychromatic optical vortex. Jones calculus and vector beam characterization are carried out to analyze the broadband phase compensation. A dual-twisted configuration further extends the working band to over 600 nm. It supplies an ultrabroadband and reflective solution for the WDM/MDM-compatible elements and may significantly promote advances in ultrabroadband planar optics.

Performance-based design and manufacturing of filament wound Type-4 cylinders for compressed gas storage

Filament wound type-4 cylinders are widely used in automotive applications for the storage of compressed gases. The performance of the storage cylinders critically depends on their manufacturing parameters. These paramters include the material properties of the reinforcement and matrix material, the number of fiber spools used during winding, the fiber bandwidth, the initial fiber band volume fraction, the mandrel geometry, the winding sequence, and the composite layer thickness distribution. An interim link between the critical parameters, the composite thickness distribution and the amount of fiber and resin consumed for winding a type-4 composite vessel has been established using an analytical model in this study. The developed model is validated by manufacturing the cylinder and comparing the theoretical and experimental results. The composite layer distribution across the entire geometry of the vessel is included into an FEA model to predict the burst pressure and weight of the obtained type-4 cylinder with greater precision. The given study can be used to design low-cost high burst performing type-4 composite structures with significant weight reduction.

Extending laser wavelengths to 1630 nm in centimeter-scale Er-phosphate fiber.

The spectral bandwidth of Er-doped fibers limits their lasing wavelength at longer wave band. Here, to the best of our knowledge, we report a broad emission band (1420‒1680 nm) of Er3+ and demonstrate for the first time an Er-phosphate fiber, which supports laser oscillation at the extended wavelengths of 1627 nm and 1630 nm, with the output powers and slope efficiencies of 44 mW/12.5% and 16.5 mW/5.6%, respectively, pumped at 1480 nm. To the best of our knowledge, these are the highest output powers and slope efficiencies at 1627 nm and 1630 nm from an Er3+-doped all-fiber configuration.

Stochastic decoherence induced by polarization mode dispersion

We address the propagation of entanglement in fibers and investigate the decoherence of polarization-entangled photon pairs caused by polarization mode dispersion (PMD). We devise a decoherence model starting from the statistical properties of polarization mode dispersion and obtain the density matrix describing initially maximally entangled states at any time. Using these results, we derive how decoherence depends on the length of the fibers. We calculate the mean concurrence of the entangled states with PMD effects as a function of fiber length, bandwidth, and other parameters in different cases.

Parameter Study and Economic Efficiency Optimization for Laser Cladding with Wide-Band Fiber Laser

With the aim of investigating the cladding geometry characteristics by a wide-band fiber laser with coaxial rectangular nozzle, and optimizing the powder efficiency and deposition speed for economy efficiency, Fe-based alloy powder was deposited on AISI 1045 substrate by a 3000 W fiber laser in this study. Laser power (P), scan speed (V), and powder feed rate (F) were selected for a factorial design. The effects of the three process parameters on the geometry characteristics and economic efficiency of single tracks were statistically analyzed, and a linear regression model was established between the combined parameters and the relevant characteristics (including track height, ratio of track width to height, powder efficiency, and deposition speed). A process map was developed with the track shape and key economic indexes as boundaries. A flat-top feature of the track profile was found and can be utilized to achieve good cladding evenness. The process map showed that the powder efficiency and deposition speed were higher than 50% and 20 mm3/s, respectively, when selecting process parameters in the as-built operation window.

Studying the effect of changing Input conditions on MMF using MGDM technique

The mode group diversity multiplexing (MGDM) multicast technology uses optical multiple input and output (O-MIMO) technology to provide greater capacity and the ability to transmit information over multi-mode fiber (MMF). The MGDM system has a benefit in terms of capacity expansion, which led to interest in its use in most optical communications. The MGDM exploits the optical fiber bandwidth by inserting spatial light detection, which increases the capacity of the MMF. This research aims to study the optical systems used for the MGDM technology, and to identify the methods of their analysis and design of O-MIMO systems to increase the amplitude of this signal. The conditions of light entry into the optical fiber such as typical spot size, radial displacements, angle, wavelength, and radius of the detectors sections are improved. Numerical MATLAB simulation is used to improve the amplitude of graded index multimode fiber (GI-MMF) and compared to the existing aggregation systems. Moreover, this method was simulated to improve the input and detection conditions to increase the O-MIMO capacity using the MGDM technique. Finally, the capacity of the MGDM system was studied and compared with different channels, and it is noticed that the capacity of the system increases with increasing the number of channels.

Multi-color switchable visible light source generated via nonlinear frequency conversion of a random fiber laser.

Nonlinear frequency conversion of random fiber lasers could provide new possibilities to realize visible and mid-infrared light with flexible wavelength and low temporal/spatial coherence. Frequency doubling of random fiber laser is reported to generate visible light with single-color output. Here, we propose a new way to generate multi-color switchable visible light source from a dual-wavelength switchable 1st-order random Raman fiber laser (RRFL) with phosphosilicate fiber. Taking advantage of the existence of the two Raman gain peaks with significant different Raman gain bandwidth at the frequency shifts of 13.2 THz (silica-related one with broad Raman gain bandwidth) and 39.9 THz (phosphorus-related one with narrow Raman gain bandwidth) in phosphosilicate fiber, a dual-wavelength switchable RRFL is developed which can emit 1120 and 1238 nm random Raman lasing individually or simultaneously with 3-watt level output power and sub-1 nm bandwidth by precisely tuning the pump wavelength to manipulate the Raman gain at two fixed Raman Stokes wavelengths. It is expected that the output power can be further increased with a shorter fiber length and more powerful pump, and the spectral bandwidth can be much narrower by adopting a narrowband point reflector in 1st-order RRFL. Based on the dual-wavelength RRFL with a flexible power ratio and a periodically poled lithium niobate (PPLN) crystal array containing three separate poled gratings with different periods, the second-harmonic generation of 1120 nm or 1238 nm random lasing and sum-frequency generation of 1120 nm and 1238 nm random lasing can be performed. As a result, the switchable output of green light at 560 nm, yellow light at 588 nm and red light at 619 nm can be realized with optical power of 22.2 mW, 16.9 mW and 18.5 mW, respectively. Our work demonstrates dual-wavelength RRFL could act as a new platform for generating visible light source with flexible color output which has potential applications in imaging, sensing and visible temporal ghost imaging.

Dynamic Bandwidth Allocation for C-Band Shared FBG Sensing and Telecommunications

The telecommunications data transfer in single-mode (SM) optical fiber (OF) of a passive optical network (PON) is managed by dynamic bandwidth allocation (DBA). In most Internet of Things (IoT) sensor network applications, both raw sensing signals and telecommunication data are transmitted in SM OFs, too. At the present time, this is not done in a shared SM OF. This article presents a novel concept to share fiber Bragg grating (FBG) sensing and telecommunication services (TS) in the optical C-band of the shared transmission. This concept is based on statistical detection and monitoring of FBGs sensing signals. The key steps of the proposed concept are FBG power spectral peaks statistical detection, monitoring of the FBGs dynamics, and periodical estimation of telecommunication channels (TChs) occupancy and availability. The proposed concept was demonstrated and validated using the sensor network with a deployed group of FBG-based sensors, by implementing various static or dynamic approaches. By doing so, we achieved TChs bandwidth availability approaching 80%, compared to previously wasted bandwidth with availability at most 15.6%. The experimental results showed that a DBA system with implemented dynamic TChs occupancy is a reliable way to share fiber bandwidth between both FBG sensing and TChs.

Investigation of bandwidth in multimode W-type microstructured plastic optical fibers

By employing the time-dependent power flow equation (TD PFE), we examine the bandwidth in multimode W-type (double clad) microstructured plastic optical fibers (mPOFs) with a PMMA (polymethyl methacrylate) solid core for parametrically varying depth and width of the intermediate layer (IL) (inner cladding). The investigated W-type mPOF's bandwidth was calculated for various configurations of the air-holes in the inner cladding and varied launch excitations. We obtained that results for smaller inner cladding air-holes at longer fiber lengths exhibit greater bandwidth. On the other hand, for shorter fibers, the launch beam which only excites guided modes, has no effect on the bandwidth due to the air-hole size. The W-type mPOF with a narrower inner cladding has a greater bandwidth. The bandwidth is also larger for a narrow launch that only excites guided modes as opposed to a wider launch that excites both guided and leaky modes. Therefore, the bandwidth increases as the width of the IL is reduced, or by decreasing the diameter of air-holes in the IL, or by exciting only guided modes. W-type mPOFs can be more easily tailored for a specific use in optical fiber sensors and communications because to their programmable properties.

Differential mode delay and modal bandwidth measurements of multimode fibers using frequency-domain method

• A frequency-domain method is developed to measure the DMD of multimode fibers. • Vector network analyzer is used to measure the complex transfer functions. • The time-domain output pulses can be calculated from CTF with proper procedures. • Frequency-domain method yields DMD results equivalent to the time domain method. • The frequency domain method can conduct DMD measurements at very low optical power. We report a frequency-domain method for measuring the differential mode delay (DMD) and bandwidth of multimode fibers (MMFs). Using a frequency domain instrument, vector network analyzer (VNA), the method measures the complex transfer functions (CTFs) of multimode fibers for a given set of launch conditions. As a result of the fiber length, which is long relative to sampling points used in VNA, the frequency sampling is under-sampled and the measured CTF is aliased. Aliased CTF behaves very differently from fully sampled CTF with dependence on the sampling frequency step. With proper procedures, the CTF can be transformed to local time frame centered around DMD into a modified CTF. The time-domain output pulses can be further recovered through an inverse Fourier transform. By recovering output pulses using complex transfer functions of a multimode fiber at controlled launch offsets, one can subsequently follow the same procedures of existing time domain methods to determine the effective modal bandwidth of the multimode fiber under test (FUT). As a result of the method, DMD and modal bandwidth measurements can be undertaken using frequency domain instruments rather than time domain instruments in a mathematically equivalent manner for multimode fibers. The measurement method utilizes CW light sources that are readily available in a wide range of wavelengths, thus providing greater flexibility for measuring the modal bandwidth of MMFs at different wavelengths, including WDM applications other than 850 nm. The very high sensitivity of the VNA allows the measurement at much lower optical power compared to the time domain instrument. Several measurements at 850 nm have been conducted using the frequency domain method and validated by comparison with the results from the time domain method. The method is suitable for measuring MMFs from a short length of a few hundred meters to a very long length close to 20 km. We have also measured an MMF at 910 nm using the method to demonstrate its flexibility in adopting different wavelengths.

Switchable wide-band multi-wavelength fiber laser via Brillouin random lasing resonance

A switchable wide-band multi-wavelength Brillouin-erbium fiber laser constructed by a sub fiber loop (SFL) containing an erbium-doped fiber amplifier (EDFA) and a main fiber cavity (MFC) including a 1-km length of high nonlinear fiber (HNLF) via Brillouin random lasing resonance is proposed and experimentally investigated. The EDFA is incorporated into the sub fiber loop to boost optical power of the externally injected Brillouin pump (BP) light and Stokes wave fed back from the MFC, and the amplified BP light and Stokes wave are forward launched into the HNLF via the SFL, meanwhile, the generated Stokes wave is partially backward injected into the HNLF via the MFC, which make the Brillouin random lasing resonance of the Stokes wave form in the laser cavity. Using the proposed scheme, up to 19-orders backward-output Brillouin Stokes lines with a peak power discrepancy of less than 10 dB, and 281 stable forward-output Brillouin Stokes lines with a peak power discrepancy of less than 30 dB are obtained from the different output ports of the laser. Compared with the previous results, the backward generated Brillouin Stokes lines increase from 11 to 19 orders and the spectral-lines compositions also happen to change, and the forward generated stable Brillouin Stokes lines span over 30 nm and are extended by more than 18 nm. It is obvious that the generated Brillouin Stokes lines significant increasing should owe to the Brillouin random lasing resonance being introduced into the laser cavity. Influences of the system parameters including the BP power, EDFA pump power, and feedback power of Stokes wave on the laser lasing are investigated in detail. The proposed multi-wavelength fiber lasers can backward generate switchable Brillouin Stokes lines from 1st order to 19th order with an increasing wavelength number in turn, only by adjusting the EDFA pump power; moreover, the wavelength interval of the backward generated Brillouin Stokes lines can be switched between double- and single-Brillouin frequency shift, only by adjusting feedback power of the Stokes wave, without adding additional system configuration. A statistical analysis for the randomness of the multi-wavelength Brillouin-erbium fiber lasers is also done.

Simple and cost-effective broad bandwidth fiber chirped pulse amplification laser system seeded by a nonlinear amplifier.

In this paper, we demonstrate a simple and cost-effective fiber chirped pulse amplification (CPA) laser system, where a nonlinear amplifier is employed to generate broadband seeding pulses. The nonlinear amplifier can generate stable pulses with 50 nm spectral bandwidth and linear chirp. With such a seeding configuration being adapted into a fiber CPA laser system, the output bandwidth can be expanded from 7 nm to 20 nm, with only minor changes to a standard industrial fiber CPA system. The increased bandwidth allows for pulse durations of less than 100 fs, which is significantly shorter than the original configuration's 250 fs. When combined with a Fourier pulse shaper, such a fiber laser system is expected to produce pulses with energy exceeding 100 µJ and duration shorter than 100 fs.