Large Effective Area Fiber Research Articles

150 x 120 Gb/s unrepeatered transmission over 409.6 km of large effective area fiber with commercial Raman DWDM system.

15 Tb/s unrepeatered transmission is achieved over 409.6 km (68.2 dB) of large effective area fiber using forward and backward distributed Raman amplification and a remotely-pumped erbium-doped optical amplifier. This result provides a record capacity-reach product of 6.14 Pb/s-km over a single fiber type. We also demonstrate channel growth from 10 to 150 waves within 61 nm amplification bandwidth.

Realization of soliton interaction in 100 Gbps, uncompensated single channel telecommunication system implemented with various telecom fibers

In this paper, we demonstrate the effect of soliton interaction in 100 Gbps telecommunication system implemented with four types of practically deployed telecom fibers like conventional single mode fiber, Alcatel’s teralight fiber, Lucent’s truewave plus fiber (TW+) and large effective area fiber. With the initial relative spacing of in-phase soliton chosen as q\(\,=\,\)5.28, the characteristic soliton interaction point and the collision length with respect to various fiber types were studied. The practical undesirability of soliton interaction is noted for three collision period with all types of fibers to characterize the degradation after successive collisions. Besides studying the soliton interaction, we have also demonstrated its effect in telecommunication system degradation with the performance measures like Quality factor and eye patterns. Eye patterns were used to picture the mechanism of soliton interaction within the collision length. It was found system implemented with TW+ fiber of low dispersion co-efficient comparatively has long interaction length and suitable for long distance transmission without dispersion compensation.

Comparison of 80 × 112-Gb/s PDM-QPSK system performance over large effective area fiber and standard SMF with Raman amplification.

We experimentally investigate the transmission performance of 80 × 112-Gb/s polarization-division-multiplexed quadrature phase shift keying (PDM-QPSK) signals over large effective area fiber and standard single mode fiber (SSMF) links with Raman amplification. The large effective area fiber offers higher optimum launch power and longer reach than SSMF. The maximum reach of 5200-km is obtained using large effective area fiber. The Gaussian noise (GN) model is explored to fit with experimental data for optimum power.

High-Level QAM OFDM System Using DML for Low-Cost Short Reach Optical Communications

In this letter, we experimentally demonstrated a high level quadrature amplitude modulation (QAM) optical orthogonal frequency division multiplexing (OFDM) transmission system utilizing a cost-effective directly modulated laser. This experiment was enabled by intrasymbol frequency-domain averaging-based channel estimation, large fast Fourier transform size to enhance the resistance of intersymbol interference, and the discrete Fourier transform-spread technique to reduce peak-to-average power ratio. A 31.7-Gbit/s 2048QAM OFDM signal can be successfully transmitted over 20-km large effective area fiber under a 20% soft-decision forward-error-correction threshold (bit error rate of 2.4 × 10-2).

Unrepeatered 256 Gb/s PM-16QAM transmission over up to 304 km with simple system configurations.

We study unrepeatered transmission of 40x256 Gb/s systems with polarization-multiplexed 16-quadrature amplitude modulation (PM-16QAM) channels using simple coherent optical system configurations. Three systems are investigated with either a homogeneous fiber span, or simple two-segment hybrid fiber designs. Each system relies primarily on ultra-low loss, very large effective area fiber, while making use of only first-order backward pumped Raman amplification and no remote optically pumped amplifier (ROPA). For the longest span studied, we demonstrate unrepeatered 256 Gb/s transmission over 304 km with the additional aid of nonlinear compensation using digital backpropagation. We find an average performance improvement in terms of the Q-factor of 0.45 dB by using digital backpropagation compared to the case of using chromatic dispersion compensation alone for an unrepeatered span system.

Study of EDFA and Raman system transmission reach with 256 Gb/s PM-16QAM signals over three optical fibers with 100 km spans

We compare the transmission performance of three different optical fibers in separate 256 Gb/s PM-16QAM systems amplified with erbium doped fiber amplifiers (EDFAs) and distributed Raman amplification. The span length in each system is 100 km. The fibers studied include standard single-mode fiber, single-mode fiber with ultra-low loss, and ultra-low loss fiber with large effective area. We find that the single-mode fiber with ultra-low loss and the large effective area fiber with ultra-low loss afford reach advantages of up to about 31% and 80%, respectively, over standard fiber measured at distances with 3 dB margin over the forward error correction (FEC) threshold. The Raman amplified systems provide about 50% reach length enhancement over the EDFA systems for all three fibers in the experimental set-up. For the best performing fiber with large effective area and ultra-low loss, the absolute reach lengths with 3 dB margin are greater than 1140 km and 1700 km for the for EDFA and Raman systems, respectively.

Distributed Strain and Temperature Measurement by Brillouin Beat Spectrum

A novel distributed strain and temperature measurement method based on Brillouin beat spectrum (BBS) in a complex index profile fiber are proposed. The BBS corresponds to the optical interaction of different acoustic modes. For a large-effective-area fiber (LEAF), the first peak of BBS is contributed by the first and second acoustic modes, while the second peak in BBS is contributed by the first and third accoustic modes. Through determining power changes in the peaks of BBS due to strain and temperature variation along a LEAF, the distributed strain and temperature can be measured by the homodyne Brillouin optical time-domain reflectometry (BOTDR) without scanning the Brillouin spectrum. The strain and temperature at the end of a 4.5-km LEAF are measured at 3-m spatial resolution in 140 s.

Design of Symmetric dispersion compensated, long haul, Single and Multichannel Optical Lightwave Systems in Telecommunications: Theory, Background and Simulation Model-A Study

Here we propose a model on Enhanced- Large Effective Area Fiber (E-LEAF) and Dispersion Compensation Module (DCM) with precise designed Dispersion Compensation Fiber (DCF). The Model is implemented in a long haul Single and Multichannel Optical telecommunication systems with E-LEAF as data transmission Fiber (NZ-DSF) of 1700Km (85 Km SMF×20 loops) length. The DCM is proposed in Symmetric Compensation fashion consisting of 20Km (2Km×20spans) length DCF in Pre-Compensation and Post- Compensation totally comprising of 40Km length DCF for complete Compensation of total Optical Link. Thereby, we study the effect of various Line Coding Schemes like NRZ, RZ, CS-RZ, DUOBINARY and MODIFIED DUOBINARY in single and multichannel optical link with our designed DCM and concluded the suitable line coding scheme for our proposed model. This paper focus on the theoretical background, design procedures, technical terms and finally a simulation model is experimented with proposed parameters to realize the foresaid concepts with various modulation formats.

Logarithmic versus modified digital backward propagation algorithm in 224<inline-formula><math display="inline" overflow="scroll"><mrow><mtext> </mtext><mtext> </mtext><mi>Gb</mi><mo>/</mo><mi mathvariant="normal">s</mi></mrow></math></inline-formula> DP-16QAM transmission over dispersion uncompensated fiber links

We have numerically evaluated the transmission performances of digital backward propagation (DBP) algorithms based on the step-size selection methods: (a) constant step-size based modified DBP (M-DBP) and (b) logarithmic step-size based DBP (L-DBP). The nonlinear tolerance of homogeneous dispersion un compensated fiber links are compared in 224 Gb/s DP-16QAM transmission over 656 km of diverse fiber types, i.e., standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF), large effective area pure-silica-core-fiber (LA-PSCF), large effective area fiber, and true wave classic. In the case of homogeneous fiber links, LA-PSCF exhibits higher non linear threshold and gains 32% more transmission distance as compared with SMF by employing M-DBP, while we have observed an additional 13% increase in transmission distance by employing L-DBP.

50 GHz Spaced 25 × 40 Gbit/s WDM Transmission Over 560 km Using SMF-Based Large Effective Area Fiber (LEAF)

In this paper, we present 50 GHz spaced 25 <img src=image/10.5923.j.ijoe.20120201.04_001.gif></img> 40 Gbit/s WDM transmission over 560 km using SMF-based Large Effective Area Fiber (LEAF) in a recirculating loop. The paper uses band-limited RZ signals carrying 2<SUP>31</SUP>-1 PRBS data, and shows that transmission distance of 560 km can be achieved with BER ≤ 10<SUP>-9 </SUP>using 1 mW peak power and 4 ps pulse-width for each data signal. To attain this, optical filters with sharp transmission characteristics are used in both transmitter and receiver. The results demonstrated in this paper are based on simulation, and the author believes that the propagation distance reached in the paper is the longest distance achieved for such system

Experimental investigation of 84-Gb/s and 112-Gb/s polarization-switched quadrature phase-shift keying signals

We experimentally investigate 28-GBd (84-Gb/s) and 37.3-GBd (112-Gb/s) polarization-switched quadrature phase-shift keying (PS-QPSK) signals. In single-channel transmission experiments over up to 12500 km ultra large effective area fiber, we compare their performance to that of polarization-division multiplexing quadrature phase-shift keying (PDM-QPSK) signals at the same bit rates. The experimental results show that PS-QPSK not only benefits from its better sensitivity but also offers an increased tolerance to intra-channel nonlinearities.

Impact of Channel Count and PMD on Polarization-Multiplexed QPSK Transmission

Through graphics-processing-unit-based simulations with different numbers of copropagating channels (1--81), the dependence of the nonlinear threshold on channel count, as well as on the fiber polarization mode dispersion (PMD) coefficient, is investigated for both dispersion-managed and DCM-free 40 and 100 Gb/s coherent-detected polarization-multiplexed quadrature phase-shift keying (CP-QPSK) transmission systems. Different fiber types including standard single-mode fiber (SSMF), large effective area fiber (LEAF), and truewave classic fiber (TWC) are considered and compared. Our investigations show that the required number of simulated copropagating channels to correctly simulate the nonlinear penalty caused by interchannel nonlinearities on CP-QSPK modulation is strongly dependent on the fiber type. The generally used assumption of around ten channels for simulating interchannel nonlinearities is only valid for the SSMF with relative low channel input power. For transmission links consisting of fiber types with low dispersion or high nonlinear coefficients, such as the LEAF or TWC, ten copropagating channels are clearly not sufficient. In dispersion-managed systems with DCMs, the required number of simulated copropagating channels is not only dependent on fiber types and data rates but also strongly on PMD present in the links. Our investigations have indicated that for transmission over fibers with very low PMD (this is the case of most new fibers), ten copropagating channels are not sufficient to correctly characterize the interchannel nonlinearities even for high-dispersion fiber types, such as the SSMF, and hence causes a clear underestimation of the nonlinearity penalty. Finally, synchronized and interleaved CP-QPSK is compared. We show that despite the depolarization effect of PMD, there are still some benefits of using interleaved RZ-CP-QPSK systems.

Design and analysis of dual-shape-core large-mode-area optical fiber

We present a large effective area fiber design using dual-shape core (DSC) fiber. The fiber is essentially a depressed-index clad fiber with a dual-shape-core consisting of a large central core and a small slightly lower-index side core. The refractive indices of the two cores are so chosen as to perfectly guide the fundamental mode. All the higher-order modes of the fiber are leaky. The fiber shows large-mode-area single-mode operation by higher-order modes discrimination. We have analyzed the structure by using the transfer matrix method. Our numerical simulation results suggest that the DSC fiber can have single-mode operation with effective mode area as large as 580 μm2 and low bending loss. The bending loss of the fiber could be brought down by more than 2 orders of magnitude compared to the corresponding step-index fiber. We also show that the mode field area is relatively insensitive to design parameters in comparison to the leakage loss of the mode. The fiber is amenable to fabrication by modified chemical vapor deposition technology and is expected to find applications in high power fiber lasers and amplifiers.

Novel Low-Bend Large Effective Area Fiber for Fiber-to-the-Home Application

In this article, with sophisticated modification on modal field distribution and introducing a new design procedure, a single-mode fiber with ultra-low bending loss and large effective area (Aeff) that is appropriate for a fiber-to-the-home operation is presented. The bending loss optimization procedure is based on the genetic algorithm. The most remarkable feature of this methodology is designing a bend-insensitive fiber without reduction of core radius and mode field diameter. The designed structure exhibits very small bending loss and large Aeff simultaneously. Simulation results show bending loss of 2.7 × 10−3 dB at 1.55 μm for a single turn of 5-mm radius. The calculated mode field diameter and Aeff for the designed structure are 9.00 μm and 63.62 μm2, respectively.

Broadly tunable multiwavelength fiber laser with bismuth-oxide EDF using large effective area fiber

A multiwavelength laser comb using 2.49 m Bismuth-oxide erbium-doped fiber (Bi-EDF) with different lengths of large effective area fiber (LEAF) in a ring cavity configuration is realized. The Bi-EDF is used as the linear gain medium and LEAF is used as the non-linear gain medium for stimulated Brillouin scattering. Out of the four different lengths, the longest length of 25 km LEAF exhibits the widest tuning range of 44 nm (1576 to 1620 nm) in the L-band at 264 mW pump power and 5 mW Brillouin pump power. In addition, a total of 15 output channels are achieved with total average output power of −8 dBm from this laser structure. All Brillouin Stokes signals exhibit high peak power of above −20 dBm per signal and their optical signal-to-noise ratio of greater than 15 dB.

Transmission of 40×200 Gbit/s polarisation division multiplexed quadrature phase shift keyed channels over 6600 km

The first transoceanic WDM transmission at 200 Gbit/s, using PDM-QPSK, coherent detection, ultra-low-loss large effective area fibre and erbium-doped fibre amplifiers is demonstrated.

Long-haul WDM transmission of 448 Gbit/s polarisation-division multiplexed 16-ary quadrature amplitude modulation using coherent detection

The transmission of a PDM-QAM16 signal at 400 Gbit/s over 1200 km in a WDM environment is demonstrated. The WDM link carrying 40 PDM-QAM16 channels modulated at the same bit rate incorporates ultra-low-loss, large effective area fibre and erbium-doped fibre amplifiers.

On the Tolerance of 111-Gb/s POLMUX-RZ-DQPSK to Nonlinear Transmission Effects

We experimentally investigate the tolerance of 111-Gb/s polarization multiplexed-return to zero-differential quadrature phase-shift keying (POLMUX-RZ-DQPSK) to the different nonlinear transmission impairments in different links structures. We analyze the effect of dispersion maps for four different fiber types and show that with sufficiently large per-span under-compensation in the double periodic dispersion map, a dispersion managed (DM) link can nearly have a similar performance to a non-DM link. Furthermore, we confirm that the super large effective area fiber family can provide around 3 dB advantage in the tolerance to nonlinear effects compared to standard single-mode fiber. Finally, we demonstrate that interleaving the two polarization tributaries of the 111-Gb/s POLMUX-RZ-DQPSK signal provides only a negligible advantage in terms of tolerance to nonlinear effects.

Experimental study on stimulated Rayleigh scattering in optical fibers

The linewidth, the threshold, and frequency shift of the stimulated Rayleigh scattering (STRS) in single mode fiber (SMF-28e), large effective area fiber (LEAF) and polarization maintaining fiber (PMF) have been studied using heterodyne detection to separate the Brillouin scattering with a fiber laser for the first time to the best of our knowledge. Experimental results show that the linewidth of STRS and spontaneous Rayleigh scattering are ~9 kHz, ~10 kHz, and ~11 kHz, and ~25 kHz, ~30 kHz, and ~27 kHz for SMF-28e, LEAF and PMF, respectively. The threshold power for STRS for 2 km SMF-28e, 7 km LEAF, and 100 m PMF are 11 dBm, 4.5 dBm and 16.5 dBm, respectively. The measured Rayleigh gain coefficient is a 2 × 10(-13) m/W for SMF-28e. Also, weak frequency shift could be observed when input power is large enough before SBS occurred. Because of the properties of narrower bandwidth and lower threshold power of STRS in fibers, some of applications, such as narrower filter, could be realized.

Thermal characterization of optical fibers using wavelength-sweeping interferometry

In this paper, we report a new method of thermal characterization of optical fibers using wavelength-sweeping interferometry and discuss its advantages compared to other techniques. The setup consists of two temperature-stabilized interferometers, a reference Michelson and a Mach-Zehnder, containing the fiber under test. The wavelength sweep is produced by an infrared tunable laser diode. We obtained the global phase shift coefficients of a large effective area fiber and gold-coated fiber optics with a 10(-7) accuracy.