Fiber Optical Parametric Amplifier Research Articles

One-pump fiber optical parametric amplifiers: from the pulsed to the continuous wave operation

The characteristics of one-pump fiber optical parametric amplifiers (1-P FOPAs) are theoretically investigated as the temporal width of the input pump increases from the pulsed to the continuous wave (CW) regime. Coupled nonlinear Schrodinger equations are numerically solved, and the pulse width of the pump is gradually increased to simulate the evolution of the gain and output spectra of the 1-P FOPA from the pulsed to the CW operation. The results show that the quasi-CW operation is achieved when the pulse width is about 500 fs. Also, when the temporal width of the pump increases and lies in the picosecond regime, the characteristics of FOPA recover those of the FOPA operated in the CW regime.

Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

Noise in phase-(in)sensitive dual-core fiber parametric amplification.

Flat and wide-bandwidth gain spectrum, along with phase-sensitive gain with no need to generate amplifier input idlers, can be achieved with a coupled dual-core fiber optical parametric amplifier. In this paper, we analyze the noise properties of such an amplifier. We achieve a 3 dB noise figure in the phase-insensitive case and a minimum of -6 dB noise figure in the phase-sensitive configuration. An alternative phase-sensitive configuration is also studied, that avoids the use of idlers at the input of the amplifier, leading to a 3 dB flat spectrum combined noise figure for the output signals. Pump transfer noise in phase-insensitive and phase-sensitive configurations is also studied along with the noise figure variation against the length of the amplifier.

The effect of pump parameters on dual-pump fiber optical parametric amplifier

The impact of pump parameters on dual-pump (2-P) fiber optical parametric amplifier (FOPA) is investigated. The four-wave model of coupled amplitude equations with fiber losses and pump depletion are solved numerically for the calculation of the parametric gain. Simulation results indicate that an increase in pump powers does not only enhances the parametric gain but also flattening the amplification bandwidth. Moreover, separating the pumps wavelengths further from each other can also improve the flatness of the bandwidth. Besides that, the parametric gain flatness can be improved when the separation between the pump central wavelength and zero-dispersion wavelength is small. In essence, the optimal performance of 2-P FOPA can be achieved when the pump parameters are carefully tailored.

Dual-Core Fiber Optical Parametric Amplifiers With a General Pump Configuration

In this letter, we study a dual-core fiber optical parametric amplifier with its pumps having the arbitrary power and phase distributions. A full analytical model is derived for such a general pumping scheme based on the rotating wave approximation, which is valid under the relatively strong coupling assumption. It is found that the parametric gain is not dependent on the coupling strength between the cores in such a dual-core fiber amplifier especially in the strong coupling regime. Based on the model and the corresponding observations, it is possible to provide an efficient analytical tool for the dual-core fiber optical parametric amplifier design and performance evaluation.

Optimizing of Raman Gain and Bandwidth for Dual Pump Fiber Optical Parametric Amplifiers Based on Four-Wave Mixing

This article has been retracted by IOP Publishing Limited as it contains substantial overlap with the following article published in Journal of Telecommunications System & Management: El-khashab et al 2018 J. Telecommun. Syst. Manage. 7 1. As a member of the Committee for Publication Ethics (COPE), IOP Publishing Limited has investigated this in accordance with COPE guidelines and it was agreed the article should be retracted. IOP Publishing Limited have been unable to contact the authors regarding this retraction, despite numerous attempts. The authors are encouraged to contact IOP Publishing Limited if they wish to contest this retraction.

Investigation of Dual-Pump FOPA Performance in a 4-Channel 40 Gbps WDM Transmission System

Fiber-optical parametric amplifiers (FOPA) are positioned as the future leading technique for optical signal amplification. This type of amplifiers is highly appreciated due to their applications in all-optical signal processing. Signal amplification can be achieved using single-pump or dual-pump pumping schemes. Dual-pump FOPAs provide smoother gain over wider bandwidth than single-pump FOPAs, but it is harder to maintain high performance of dual-pump FOPAs due to the stimulated Raman scattering (SRS) induced energy transfer from one pump to another. In this paper the authors investigate the performance of a dual-pump FOPA under the influence of SRS in order to ensure higher gain using as low pump power as possible in a 4-channel 40 Gbps wavelength-division multiplexed transmission system. DOI: http://dx.doi.org/10.5755/j01.eie.23.6.19699

Optical receiver sensitivity enhancement by single- and dual-band fiber optical parametric amplifier.

A semi-classical model is proposed theoretically and demonstrated experimentally on the optical receiver sensitivity enhancement by single-band (signal or idler) and dual-band (signal and idler) fiber optical parametric amplifier (FOPA). The sensitivity enhancement by single-band is determined by the gain of FOPA and the transmission loss of signal and idler, and it can be further improved by up to 3-dB using amplified signal and phase-conjugated idler together at dual-band configuration. The theoretical results are experimentally verified in both fiber communication and biomedical imaging applications. This detection sensitivity enhancement scheme can be potentially applied in the scenarios where ultrafast broadband signal at low-power level is being handled.

One-pump fiber optical parametric amplifier in presence of dispersion fluctuations: impact of fourth-order dispersion coefficient.

The impact of random dispersion fluctuations on the gain and saturation behavior of a one-pump fiber optical parametric amplifier (1-P FOPA) in the presence of fourth-order dispersion coefficient (β4) is investigated. Three coupled amplitude equations with fiber losses are solved numerically for the calculation of the pump, signal, and idler. The performances of 1-P FOPA are also analyzed with variation of dispersion fluctuation amplitude (σ) and correlation length (Lc). Based on the numerical results, it is found that the gain spectra and saturation curves exhibit some differences when β4 is considered. In comparison with the case where β4 is ignored, the peak gain remains the same, but the 3dB bandwidth increases when β4 exists. Another notable difference is that the saturation power is shifted to lower or higher values, depending on the σ and Lc parameters. In general, the peak gain reduces as σ increases, and the peak gain reduction is greater for the case of shorter Lc. The numerical analysis is probably useful, especially for the case where the signal wavelength is detuned far from the pump wavelength.

Suppressing chromatic dispersion fluctuation for broadband optical parametric gain in highly nonlinear tellurite microstructured optical fibers

We investigate the effect of chromatic dispersion fluctuation on the performance of fiber optical parametric amplification (FOPA) using tellurite hybrid microstructured optical fibers which have highly nonlinear coefficient and high freedom in tailoring chromatic dispersion. When a tellurite-glass buffer layer is added around the central core, the new tellurite hybrid microstructured optical fiber can suppress the fluctuation of chromatic dispersion which is caused by the variation in the core diameter and fiber transverse geometry. As a result, high signal gain and broad bandwidth of FOPA can be maintained.

In-line and cascaded DWDM transmission using a 15dB net-gain polarization-insensitive fiber optical parametric amplifier.

We demonstrate and characterize polarization-division multiplexed (PDM) DWDM data transmission for the first time in a range of systems incorporating a net-gain polarization-insensitive fiber optical parametric amplifier (PI-FOPA) for loss compensation. The PI-FOPA comprises a modified diversity-loop architecture to achieve 15dB net-gain, and up to 2.3THz (~18nm) bandwidth. Three representative systems are characterized using a 100Gb/s PDM-QPSK signal in conjunction with emulated DWDM neighbouring channels: (a) a 4x75km in-line fiber transmission system incorporating multiple EDFAs and a single PI-FOPA (b) N cascaded PI-FOPA amplification stages in an unlevelled Nx25km recirculating loop arrangement, with no EDFAs used within the loop signal path, and (c) M cascaded PI-FOPA amplification stages as part of an Mx75.6km gain-flattened recirculating loop system with the FOPA compensating for the transmission fiber loss, and EDFA compensation for loop switching and levelling loss. For the 4x75km in-line system (a), we transmit 45x50GHz-spaced signals ('equivalent' data-rate of 4.5Tb/s) with average OSNR penalty of 1.3dB over the band at 10-3 BER. For the unlevelled 'FOPA-only' 25.2km cascaded system (b), we report a maximum of eight recirculations for all 10x100GHz-spaced signals, and five recirculations for 20x50GHz-spaced signals. For the 75.6km levelled system

Effect of Pump Dithering at Each Stage of Cascaded Fiber Optical Parametric Amplifier

Cascaded fiber optical parametric amplifier (FOPA) can enhance gain and bandwidth. The gain and bandwidth can be further enhanced by dithering the FOPA pump. However, to our knowledge, the effects of a pump dithering at every stage of cascaded FOPA have not been discussed. The study of performance at every stage of cascaded FOPA is quite interesting and beneficial in designing the system. Here, we analyzed, using OptiSystem software, each stage of a cascaded FOPA, when there was a pump dithering and not. The results showed that the pump dithering enhanced the gain and broaden the bandwidth at every stage. The gain and bandwidth obtained with the pump dithering were 27 dB and 20 nm, respectively. On the other hand, when there was no pump dithering, the gain and bandwidth were 9 dB and 12 nm, respectively.

Numerical Simulation of Highly-Nonlinear Dispersion-Shifted Fiber Optical Parametric Gain Spectrum with Fiber Loss and Higher-Order Dispersion Coefficients

The previous study investigated the fiber parameters on the analytical one-pump fiber optical parametric amplifier (FOPA) gain spectrum of a loss-free highly-nonlinear dispersion-shifted fiber (HNL-DSF) and got the optimum results for each parameter. However, the FOPA gain of the combination of all the optimum values of the considered parameters was not reported. Hence, this paper intends to investigate the analytical FOPA gain of the combination of all the optimum values of the considered parameters from the previous study. Later, the analytical gain was compared with the numerical gain from the fourth-order Runge-Kutta (RK4) method and Matlab built-in function, ode45. Next, the effect of fiber loss and higher order dispersion coefficients such as fourth and sixth-order dispersion coefficients were studied. It is found that RK4 gives a smaller error and the gain reduces while the bandwidth remains same in presence of fiber loss. The fourth-order dispersion coefficient broadens the bandwidth a bit while maintaining the gain and there are two narrow-band gains generated to the left and right-side of the broad-band gain. The sixth-order dispersion coefficient just shifts the two narrow-band gains toward or away from the broadband gain depending on the positive or negative signs of the sixth-order dispersion coefficient.

Polarized fiber optical parametric amplification in randomly birefringent fibers: erratum.

We correct the value of coefficient Γ presented in Opt. Express23, 32747 (2015)10.1364/OE.23.032747, which describes the relationship between the mean output degree of polarization and the average gain of fiber optical parametric amplifiers.

Broadband Gain-Spectrum Measurement for Fiber Optical Parametric and Raman Amplifiers

We examine the use of a depolarized broadband probe to experimentally measure gain spectra of amplifiers comprising parametric and Raman gain. The suggested technique allows a quick and accurate characterization of gain spectra spanning more than 100 nm. We derive formulas for processing spectral data to address polarization dependent gain and idler generation, and consequently develop a measurement methodology for obtaining reliable results. We demonstrate the viability of this approach by performing an experimental comparison with results obtained using tunable lasers. We expect the technique described here to be useful for fiber optical parametric amplifier development and characterization.

Impact of Brillouin Backscattering on Signal Distortions in Single-Fiber Diversity Loop Based Polarization-Insensitive FOPAs

We both experimentally and numerically investigate the impact of Brillouin backscattering in single-fiber-loop-based polarization-insensitive fiber-optical parametric amplifiers. We show that the loop configuration can cause distortions in the pump spectra due to Brillouin interactions of the counter-propagating pumps. This can result in significant distortions for amplified data signals at high gain when conventional highly nonlinear fibers are used. We thoroughly investigate the effect in experiments and derive a numerical model. This allows us to compare the results from system experiments with 28 GBd quadrature-phase shift keying signals to system simulations showing a good agreement on the system. Based on the model, we finally estimate that a large gain (∼20 dB) with a low optical signal-to-noise ratio penalty (0.15 dB at bit error rate of $1 \times {10^{ - 4}}$ ) for the amplified data signal should be possible in a single-fiber loop with Brillouin-suppressed highly nonlinear fibers.

Optimized design of six-wave fiber optical parametric amplifiers by using a genetic algorithm.

A governing equation of the six-wave fiber optical parametric amplifier (FOPA) for the power and phase difference evolution of the six interacting waves is deduced. To optimize the gain of the six-wave FOPA, a multivariate stochastic optimization algorithm, i.e., the genetic algorithm (GA), is applied. The effect of pump depletion on the gain characteristic of the six-wave FOPA is emphasized and the effect of the fiber length, the wavelength, and the power of two pumps on bandwidth, flatness, and magnitude of the gain spectrum has also been studied. A broader and flatter six-wave FOPA gain is obtained by adopting optimum design parameters, which theoretically provide a uniform gain of 65dB with 0.3dB uniformity over a 110nm bandwidth for the six-wave FOPA.

20 dB net-gain polarization-insensitive fiber optical parametric amplifier with >2 THz bandwidth.

A black-box polarization insensitive fiber optical parametric amplifier (PI-FOPA) is characterized for the first time using a commercial 127 Gb/s polarization-division multiplexed PDM-QPSK transponder within a multiplex of twenty-two equivalent DWDM signals across a 2.3 THz bandwidth portion of the C-band. The PI-FOPA employs a recently demonstrated diversity loop arrangement comprising two lengths of highly nonlinear fiber (HNLF) with the parametric pump being removed after the first HNLF in both directions about the loop. This arrangement is named the Half-Pass Loop FOPA or HPL-FOPA. In total, a record equivalent 2.3 Tb/s of data is amplified within the HPL-FOPA for three different pump power regimes producing net-gains of 10 dB, 15 dB and 20 dB (averaged over all signals). For the latter two regimes, the gain bandwidth is observed to extend considerably beyond the C-band, illustrating the potential for this design to amplify signals over bandwidths commensurate with the EDFA and beyond. Under the 15 dB gain condition, the average OSNR penalty to achieve 10-3 bit error rate for all twenty three signals was found to be 0.5 ± 0.3 dB. Worst case penalty was 0.8 ± 0.3 dB, verifying the use of the architecture for polarization insensitive operation. The growth of four-wave mixing signal-signal crosstalk is additionally characterized and found to be gain independent for a fixed output power per signal. A simple effective length model is developed which predicts this behavior and suggests a new configuration for significantly reduced crosstalk.

Parametric amplification with a dual-core fiber.

In this paper we theoretically derive for the first time a matrix formalism for a coupled dual-core fiber optical parametric amplifier (FOPA). One of the most advantageous properties of this degenerate pump FOPA is the spectrally flat gain obtained when certain design parameters are met. This flat gain is obtained either in phase-sensitive (PS) or phase-insensitive (PI) operation of the dual-core FOPA. Properties such as maximum and minimum PS gain, along with maximum bandwidth and difference between maximum PS and PI gain are also investigated.

Ultra-flat wideband single-pump Raman-enhanced parametric amplification.

We experimentally optimize a single pump fiber optical parametric amplifier in terms of gain spectral bandwidth and gain variation (GV). We find that optimal performance is achieved with the pump tuned to the zero-dispersion wavelength of dispersion stable highly nonlinear fiber (HNLF). We demonstrate further improvement of parametric gain bandwidth and GV by decreasing the HNLF length. We discover that Raman and parametric gain spectra produced by the same pump may be merged together to enhance overall gain bandwidth, while keeping GV low. Consequently, we report an ultra-flat gain of 9.6 ± 0.5 dB over a range of 111 nm (12.8 THz) on one side of the pump. Additionally, we demonstrate amplification of a 60 Gbit/s QPSK signal tuned over a portion of the available bandwidth with OSNR penalty less than 1 dB for Q2 below 14 dB.