Nonzero Dispersion-shifted Fiber Research Articles

Experimental demonstration of optical waveform transmission with multiple-eigenvalue 16-APSK modulation.

The multi-eigenvalue multiplexing-based discrete spectrum-modulated nonlinear frequency-division multiplexing (DS-NFDM) system with higher-order modulation format has been demonstrated experimentally. After designing the coefficients of the eigenvalue set and the constellation point distribution of 16-amplitude phase shift keying (16-APSK), the realizations of 14-, 30-, and 46-eigenvalue multiplexed DS-NFDM signals have been implemented. The results show that 46-eigenvalue and 30-eigenvalue multiplexed DS-NFDM signals can transmit 50 km and 400 km over a nonzero dispersion-shifted fiber (NZDSF) under soft-decision forward error correction (SD-FEC) threshold of 2.4E-2, respectively. This demonstration shows for the first time, to the best of our knowledge, the record for multiplexed eigenvalue number and data rate of the multiple-eigenvalue-based DS-NFDM system.

Experimental Demonstration to Enhance the Curvature Sensitivity of a Fiber Mach–Zehnder Interferometer Based on a Waist-Enlarged Technique Using Polymer

A fiber curvature sensor based on a Mach–Zehnder Interferometer (MZI) constructed using the waist-enlarged technique to splice a segment of non-zero dispersion-shifted fiber (NZ-DSF) between two segments of single mode fiber (SMF) is proposed and experimentally demonstrated. All fabricated sensors presented an improvement in their curvature sensitivity when they were coated with polydimethylsiloxane (PDMS) polymer. The sensor that exhibited the best performance was 6.5 cm long, with a curvature sensitivity of 8.27 nm/m−1 in a range of 0.69 m−1 (from 1.08 to 1.77 m−1). This sensitivity is 3.22 times higher than that of the sensor without polymer. Additionally, the sensor coated with polymer exhibited cross-sensitivity that is 2.23 times smaller than the sensor without polymer. The easy fabrication and notable performance of this device makes it alluring for structural health monitoring.

Transmission challenges in metropolitan area optical networks

Abstract For implementing wide/metropolitan area network in optical fiber communication system the key technology that can be utilized is wavelength division multiplexing (WDM). We discuss the use of WDM in metropolitan networks along with its special feature of using optical add drop multiplexers and also design issues in implementing these systems. The issue of nonlinear crosstalk induced in metropolitan networks is considered in terms of power penalty. Also, the effect of dispersion induced in optical fibers is considered by using two types of transmission systems. One is considering the non-zero dispersion shifted fiber (NZDSF) in dispersion effected environment and second is, implementing dispersion compensation after normal single mode fiber (SMF + DCF). The effect of nonlinear cross talk which can limit transmission performance is discussed in both cases in context with different parameters like power penalty, frequency difference between signal & crosstalk and transmission distance etc.

Temperature dependence of polarization mode dispersion in tight-buffered optical fibers

—Experiments and theoretical analysis of influence of temperature on polarization mode dispersion (PMD) in single mode optical fibers and cables are presented. Forces generated by contracting buffer create optical birefringence and increase fiber PMD at low temperatures. Single mode fiber (SMF) in 0.9 mm polymeric tight-buffer can exhibit an extra component of PMD exceeding 0.3 ps/√km in such conditions. On the other hand, tight-buffered spun nonzero dispersion-shifted fibers (NZDSF) and optical units with stranded single mode fibers have showed good stability of PMD over wide range of temperatures. This is due to presence of circular strain in the core, blocking accumulation of mechanically induced birefringence.

Non-Zero Dispersion-Shifted Ring-Core Fiber Supporting 60 OAM Modes

Orbital angular momentum (OAM) modes have becoming more promising to further achieve higher spectral efficiency and data capacity in space-division-multiplexing (SDM) fiber communication systems. In this work, we design and optimize a graded-index non-zero dispersion-shifted ring-core fiber (GI-NZDSRF) to support OAM modes in fiber-based transmission system. A record high number of 60 OAM modes in the C band with <10 ps/nm/km chromatic dispersion (CD) is obtained. A low differential mode delay (DMD) (<5.11 ps/m) and a large effective mode area (>1418 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of OAM modes are achieved by the designed fiber. Furthermore, the effects of fiber parameters on OAM modes are also investigated, including the index shape, doping concentration, central location, and half width of the high index region.

Effect of linewidth enhancement factor of laser diode and fiber dispersion management on high-speed optical fiber links performance and use in WDM systems

We present a numerical simulation study on the effect of the linewidth enhancement factor (α) of semiconductor laser and dispersion management methods of optical fibers on the performance of 40-Gb/s directly-modulated fiber links and their application in WDM systems. The dispersion management methods include the use of non-zero dispersion-shifted fiber (NZ-DSF), dispersion-compensating fiber (DCF), and fiber Bragg grating (FBG). The optimal values of the α-parameter and the best dispersion management method are applied to design and simulate a four-channel × 40-Gb/s WDM fiber system. The obtained results show that the increase in the α-parameter and/or fiber length reduces the performance of both the 40-Gb/s optical link and the WDM system. Regarding the 40-Gb/s optical link, when α = 1, using –NZ-DSF or + NZ-DSF, DCF with SSMF, and FBG with SSMF work to increase the transmission length from 1.6 km of a standard single-mode fiber (SSMF) to 7.2, 26.5, and 40 km, respectively. Whereas at α = 3.5, the maximum transmission length reaches 1.2 km when using SSMF, –NZ-DSF, or + NZ-DSF, while it increases to 13 and 35 km when using DCF with SSMF, and FBG with SSMF, respectively. In the designed WDM system, the use of FBG with SSMF is predicted as the most effective method for dispersion management. The maximum transmission length reaches 25 km when α = 1, but reduces to 12 km when α = 3.5.

Optical fiber signal strength based on Raman optical amplifiers schemes in dense wavelength multiplexed communication systems

Abstract This study has clarified the optical fiber signal strength based on Raman fiber optic amplifiers schemes in dense wavelength multiplexed communication systems. The signal power with, without Amplification in various pumping configurations scheme is studied with propagation distance variations. The bidirectional pumping power configuration based various pump power is analyzed with propagation distance variations. Amplified forward signal power for various fiber types is investigated with propagation distance variations. These fibers are used such as single mode (SM)-28 fiber, non-zero dispersion shifted fiber (NZDSF), truewave reach fiber for the efficient employment in fiber systems. Amplified bidirectional signal power for various both pump power and fiber types are clarified with propagation distance variations. The pumping power configurations scheme variations are demonstrated with propagation distance variations. Forward/backward pumping power configuration direction variations are investigated and clarified with propagation distance variations for various pumping power values.

Effect of fiber properties and dispersion management on distortions associated with two subcarriers modulation of laser diode in radio over fiber systems

We present numerical modeling and simulation on the effects of standard single-mode fiber (SSMF) properties and different dispersion management approaches on the distortions of laser diode. These distortions are associated with the two-tone modulation of laser diode for use in radio over fiber systems. The fiber properties include attenuation and dispersion. The dispersion management approaches include the use of nonzero dispersion-shifted fiber (NZ-DSF), fiber Brag grating (FBG), and dispersion-compensating fiber (DCF). The laser is directly modulated with two analog frequencies of 25 and 25.1 GHz at different modulation depths (m). The modulated laser signals are then propagated through SSMF at different lengths (L). The investigated laser signal distortions include the 2nd harmonic distortion (HD2), and the 2nd and 3rd intermodulation distortions (IMD2 and IMD3, respectively). The results reveal that all laser distortions are exacerbated as the fiber length increases, which is mainly due to the chromatic dispersion, while fiber attenuation has no effect. The use of dispersion management approaches gives almost similar effects on the reduction of IMD3 when L = 1 km, regardless of the value of m. Up to m = 0.3, DCF is the most effective approach for reducing all distortions over the entire fiber length range, while NZ-DSF is the least. When L = 2 km, FBG is the most effective approach for reducing both IMD2 and HD2 when m ≥ 0.4, whereas when L is increased to 6 km, DCF is the most effective approach up to m = 0.5.Graphical abstractSimulation setup of RoF system for two-tone direct modulation of laser diode using different dispersion management approaches

Design of non-zero dispersion shifted fiber with large effective area based on variational method

The determination of design parameters of large effective area fiber with segmented-core profile is presented by using simple variational method to obtain the effective area, mode field diameter, and dispersion of the fiber. The designed fiber has a large effective area of 171.1 μm2 with mode field diameter, dispersion, and normalized cut off frequency of 9.7 μm, 2.85 ps/nm.km, 2.491, respectively. The results have shown that the fiber with a bending radius of 35 mm, has a very low bending loss of 0.0053 dB/km. The calculated of parameters values of designed non-zero dispersion-shifted fiber (NZDSF) have shown that with a segmented-core profile of radius 3.5 μm, with a ring width of 0.2 μm, the core effective area Aeff increases from 152.3 μm2 to 189 μm2, which in practical point of view, is an achievement to reduce the nonlinearity effects in the NZDSF as transmission medium.

Design and Fabrication of Novel Large Effective Area Non-Zero Dispersion-Shifted Optical Fiber Based on Outside Vapor Deposition

Design and Fabrication of Novel Large Effective Area Non-Zero Dispersion-Shifted Optical Fiber Based on Outside Vapor Deposition

Traffic interception in fiber optical video-systems

In fiber-optic video systems, as well as in optical communication systems, standard single mode optical fibers (SSMF, standard G.652) are usually used. One of the advantages of these fibers is the ability to use CWDM in a wide spectrum. At the same time, more optimal near the wave-length of 1550 nm are provided by non-zero dispersion fiber (NZDSF, standard G.655) fibers. However, as studies have shown, these optical fibers have an increased sensitivity to bending. This fact can be used to traffic interception. It is shown that fiber-optics systems with SSMF have more protection from traffic interception than systems with NZDSF. To transmit a high-confidentiality video signal, special techniques, such as frequency modulation, can be used, or additional noise signals can be added.

K-means clustering-based detection for WDM PD-NOMA system with mixed fiber types

We experimentally demonstrate C-band direct-detection (DD) power division non-orthogonal multiple access (PD-NOMA) aided wavelength-division multiplexed (WDM) data transmission over 50-km distance [standard single-mode fiber (SSMF) + non-zero dispersion-shifted fiber (NZDSF)] for far user at 10-Gbps data rate. For 5-Gbps data rate, a distance of 100 km is achieved for far user. The transmission system is made of mixed fiber types to include both linear and nonlinear fiber impairments. We have utilized successive interference cancellation technique assisted by K-means clustering algorithm for the detection of the multi-user 3 × 20 Gbps on–off keying modulated WDM PD-NOMA signal. The obtained results reveal that the unsupervised K-means clustering-based DD receiver provides 7% hard decision- forward error correction BER limit of 3.8 × 10 − 3 for all three channels for both 100-/50-GHz channel spacing and 5-/10-Gbps data rates. For the case of a single-channel-based system, the BER well below the pre-FEC limit is achievable for both the data rates of 5 and 10 Gbps even after 50 km (for 10 G)/100 km (for 5 G) SSMF/SSMF + NZDSF for far user. Using the K-means algorithm, the maximum power penalty for the 10-Gbps single channel and WDM channels are 5 and 6.6 dB, respectively. The proposed detection technique is able to detect the data even for the far user at a distance of 100 km. Most significantly, no compensation techniques have been utilized for the fiber impairments in the proposed system.

Non-zero dispersion-shifted ring fiber for the orbital angular momentum mode.

As the dimension of orbital angular momentum (OAM) is orthogonal to the other degrees of freedom for photon, such as wavelength, it can be utilized to further increase data capacity in the wavelength division multiplexing (WDM) systems. However, the non-zero dispersion-shifted fiber (NZDSF) for the OAM mode has not yet been investigated or even proposed. In this work, we propose and design a ring fiber with low chromatic dispersion for the HE2,1 mode, which can serve as NZDSF for its corresponding OAM1,1 mode. A low dispersion of 3.3 ps/(nm·km) at 1550 nm and <2.9 ps/(nm·km) dispersion variation from 1530 to 1565 nm for the OAM1,1 mode is achieved in simulation, which satisfies the standard of the ITU-T G.655.C. The designed fiber with ring width from 1.5 µm to 3.5 µm can support the OAM1,1 mode within the C-band, and a large effective area of about 646 µm2 is obtained. We also note that the fiber with larger inner radius and ring width are more tolerant to the perturbations, such as fiber ellipticity and bending. In the fiber-based optical communication systems, the designed ring fiber could be used as a candidate for supporting OAM modes with low dispersion and reduced nonlinear effects.

Analysis of spectral broadening dominated by cascaded stimulated Raman scattering in optical fibers

In this work, the experimental study of spectral broadening due to stimulated Raman scattering with respect to variation of input power of pulsed laser, as well as a 4 m length high-numerical aperture fiber with 100 and 500 m of non-zero dispersion-shifted fiber is reported. The results showed extreme broadening of spectrum which is known as supercontinuum generation, originated by self-phase modulation, four- wave mixing and dominated by cascaded stimulated Raman scattering. Supercontinuum spectrum achieved by total width of 850 nm and a remarkable flatness in the range of 1500 to 1600 nm. Furthermore, output spectrum showed a total of five Stokes waves. Numerical results are also presented.

Air-Core Non-Zero Dispersion-Shifted Fiber With High-Index Ring for OAM Mode

It is well-known now that orbital angular momentum (OAM) modes can be a potential technology to take full advantages of the space resources in the fiber-based optical communication system because of its infinite states. However, the corresponding fiber design for OAM modes to meet various requirements in the fiber-based communication system is still not enough. For the dispersion property, there are various attributes given in the standard of ITU-T series, which has not yet been proposed for the OAM modes. In this paper, we propose and design a non-zero dispersion-shifted air-core ring fiber for OAM mode, which can offer more options on dispersion values. A negative dispersion of -1.246 ps/(nm·km) or a positive dispersion of 1.541 ps/(nm ·km) at 1550 nm with <; 1.5 ps/(nm ·km) dispersion variation across the C band or <; 4 ps/(nm ·km) dispersion variation across the C and L bands for OAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,1</sub> mode is achieved in the numerical simulation.

IM/DD WDM-PON Communication System Based on Optical Frequency Comb Generated in Silica Whispering Gallery Mode Resonator

This article reports an implementation of a microsphere-based optical frequency comb (OFC) generator for substitution of individual laser arrays and simulates wavelength division multiplexed passive optical network (WDM-PON) based on this OFC generator. Our proposed generator is built based on silica microsphere, barely studied for fiber optical communication systems, and is a promising solution with photonic integration capability. Kerr OFC as a multiple light source containing more than 20 spectral carriers in the fundamental mode family in the C-band and beyond is demonstrated experimentally. Four of these OFC generator carriers with the highest peak power are studied in simulated 4-channel 393 GHz spaced WDM-PON. Additionally, we show this OFC as a source of optical carriers capable of providing data transmission over most utilized fiber types in modern optical communication systems, namely, single-mode fiber (SMF), non-zero dispersion-shifted fiber (NZ-DSF), and cut-off shifted fiber (CSF). We show through the simulations that error-free data transmission is possible, providing a total transmission capacity of 40 Gbit/s by using four OFC generated carriers.

All-photonic 20-MHz clock for latency monitoring in a 5G network at 10 Gbps over optical fiber

Innovation and advancement in technologies such as self-driving cars, machine learning, remote health and factory floor automation have led to extremely stringent next-generation communication requirements. For instance, in a self-driving car, sensor data may be streamed to a cloud-based computer. Decentralized machine learning relying on augmented data may be used to control the vehicle. Large amounts of sensor data, along with the real-time nature of the applications, demand requirements on the 5G networks needed to support applications such as this. Specifications for 5G networks require extremely low end-end latency &lt; 1 m s . This latency requirement is tenfold more stringent than the 4G requirement of &lt; 10 m s . In this paper, we present a novel clock method for tracking and monitoring 5G latency. The method is all-optical, can accurately track &lt; 1 m s latency, and is spectrally efficient. We experimentally demonstrate generation of a 10 Gbps intensity-modulated data signal with 12.3 GHz carrier frequency, embedded with 20 MHz phase-modulated clock. The signal is successfully transmitted over 26.6 km of nonzero dispersion shifted fiber (NZDSF) single-mode fiber at 1550 nm. Error-free forward error correction data transmission was archived with 12.05 dB receiver penalty. Phase noise of − 40.55 d B c / H z and − 77.84 d B c / H z were attained at 1 Hz and 1 kHz offsets, respectively, for the clock.

Simulation solution for single and cascaded multi-wavelength Brillouin fiber lasers based on an analytical model

Abstract Here we propose a simulation model based on a previously reported analytical description of the Brillouin gain, that takes into account pump depletion, which allows us to make very accurate calculations for Brillouin fiber lasers (BFLs) working both in a single and cascaded multi-wavelength configurations. Output powers and conversion efficiencies are analyzed and compared with experimental results for various lasers setups using 25 km of a non-zero dispersion-shifted fiber (NZDSF) as the Brillouin gain media. In our experimental investigations, we used a pump laser at 1565 nm, with a bandwidth of 1 kHz, and output powers varying from 0 to its maximum value of 14 mW. We analyzed the laser behavior under various conditions using output couplers with output ratios varying from 10% to 90%, and to generate the cascaded Brillouin laser we have used a 10 m Erbium-doped optical fiber amplifier as a gain block in a separated cavity. Additionally, a spectral reconstruction is made based on power predictions of our model for the cascaded BFL with excellent agreement with experimental data.

Study on the simultaneous distributed measurement of temperature and strain based on Brillouin scattering in dispersion-shifted fiber

Utilizing the large effective area non-zero dispersion-shifted fiber (LEAF), a multi-parameter optical-fiber sensor has been proposed and experimentally demonstrated for distributed simultaneous temperature and strain measurement, which is based on multiple acoustic modes in spontaneous Brillouin scattering (SpBS) effect. Proof-of-concept experiments demonstrate 3 m spatial resolution over 2.5 km sensing LEAF with 2°C temperature accuracy and 60µɛ strain accuracy. The proposed distributed Brillouin optical fiber sensor allows simultaneously temperature and strain measurement, thus opening a door for practical application such as superconducting cable.

Transmission performance of the simplified receiver for 2[formula omitted]PDM-PAM, CAP and DMT signals

Based on the two polarization-division-multiplexing jointed intensity modulation and direction detection (2×PDM-IM/DD) system, the performance of the simplified receiver is studied for alternative intensity modulation formats such as PAM-4, CAP-16 and DMT. At bit rate up to ∼2×112-Gbit/s, compared with the single polarization signal, experimental results show that the power penalty of 2×PDM-PAM-4, CAP-16 and DMT is ∼0.8-dB, 1.2-dB and 1.3-dB (back-to-back) at 7% forward error correction (FEC) threshold, respectively. The transmission (i.e. 25-km non-zero dispersion shift fiber) penalty is 1.8-dB, 1.4-dB and 1.7-dB for the corresponding modulation formats. Furthermore, the comparative analysis of the simplified receiver among the three modulation formats is carried out.