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We experimentally demonstrated, for the first time, to the best of our knowledge, a two-pump fiber optical parametric amplifier having ∼26 dB on-off gain with ±1.5 dB ripple over 30 nm bandwidth.
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... The difference in net gain is the result of difference in peak power between core 1 and 2, previously mentioned. To assess the O/O gain, i.e. the difference in terms of power between the signals, when the pump is off and on, we have to add the losses of each core to its respective net gain [34]. Therefore G O/O 1 = G net1 + α 1 = 11.8 dB and G O/O 2 = G net2 + α 2 = 15.6 dB. ...
In this paper we experimentally show parametric amplification and wavelength conversion in a custom manufactured dual-core highly nonlinear fiber. On-off gain
$>$
10 dB and conversion efficiencies between
$-1$
and
$-8.5$
dB were measured for both cores. The estimated effective nonlinear parameter for the cores of the fiber are 6.6 W
$^{-1}\mathrm{km}^{-1}$
and 6.3 W
$^{-1}\mathrm{km}^{-1}$
, while the zero-dispersion wavelength for the individual cores is shown to be relatively close from each other. Furthermore, complementary analytical and numerical results show that coupled cores fiber optical parametric amplifier offer the potential of wide-band gain even when they have significantly distinct zero-dispersion wavelengths.
... These devices are based on four wave mixing (FWM) between the signal, the idler and one or two pumps in a low dispersion fiber. The two-pump FOPA (2P-FOPA) [3][4][5], provides flatter and broader gain spectrum than one pump FOPA (1P-FOPA), being more attractive for dense wavelength division multiplexing (DWDM) system applications. Because the FOPA uses a fiber with low dispersion, nearly phase matched spurious FWM between WDM signals is expected to occur, leading to undesirable crosstalk. ...
We measure four wave mixing tones generated by two signals within two pump fiber optical parametric amplifiers. Intensities of tones grow with length of fiber and signal power and show little dependence on signal separation.
... These devices are based on four wave mixing (FWM) between the signal, the idler and one or two pumps in a low dispersion fiber. The two-pump FOPA (2P-FOPA) [3][4][5], provides flatter and broader gain spectrum than one pump FOPA (1P-FOPA), being more attractive for dense wavelength division multiplexing (DWDM) system applications. Because the FOPA uses a fiber with low dispersion, nearly phase matched spurious FWM between WDM signals is expected to occur, leading to undesirable crosstalk. ...
We measure four wave mixing tones generated by two signals within two pump fiber optical parametric amplifiers. Intensities of tones grow with length of fiber and signal power and show little dependence on signal separation
... IBER optic parametric amplifiers (FOPAs), have attracted a great deal of recent interest [1][2][3][4][5][6][7][8]. These devices are based on four wave mixing (FWM) between the signal, the idler and one or two pumps in a very low dispersion fiber. ...
We measure the parasitic four wave mixing tones generated by two signals that are amplified in two-pump fiber optical parametric amplifiers (2P-FOPAs). We consider two parametric amplifiers that use different lengths of fiber and pump powers but have identical parametric gain. We observe that the parasitic tones are stronger in the 2P-FOPA with longer fiber and smaller pump power. This is in agreement with our prediction of crosstalk in 2P-FOPAs.
... In figure 3 are shown our results. The ripple is now reduced to 2 dB showing that ripple increases when pumps separation increase due to the fact that the contribution of the four order dispersion in phase match will be significant for large pump separation with the consequence of lost of the FWM phase matching [3]. That imposes a limit of the bandwidth of FOPAs that for the parameters here considered is of the order of 30 nm. ...
We have numerically shown that a two-pump fiber optical parametric amplifier can be used as a preamplifier in dense wavelength division multiplexing transmission. We observe sensitivities of -33.5 dBm (-36.5 dBm if we discount 3 dB coupler) comparable to erbium amplifiers, very low ripple and no transient response when operated in the unsaturated regime. Experimental studies on the performance of 2P-FOPAs are necessary to confirm the simulation results presented.
... A very interesting implementation predicted by Marhic et al. in 1996 [8] and Radic et al. in 2002 [53], demonstrated by Yang et al. [54], Radic et al. [53] and Boggio et al. [55] shows that a flat exponential parametric gain over with a negligible gain ripple may be achieved by using a copolarized dual pump scheme. The dual pumps here are symmetrically positioned around the zero dispersion wavelength enclosing the signal and the idler wavelength, and the wide flat gain bandwidth is generated through a cascaded coupling between nondegenerated and degenerated FPM processes. ...
An applications-oriented review of optical parametric amplifiers
in fiber communications is presented. The emphasis is on parametric
amplifiers in general and single pumped parametric amplifiers in
particular. While a theoretical framework based on highly efficient
four-photon mixing is provided, the focus is on the intriguing
applications enabled by the parametric gain, such as all-optical signal
sampling, time-demultiplexing, pulse generation, and wavelength
conversion. As these amplifiers offer high gain and low noise at
arbitrary wavelengths with proper fiber design and pump wavelength
allocation, they are also candidate enablers to increase overall
wavelength-division-multiplexing system capacities similar to the more
well-known Raman amplifiers. Similarities and distinctions between Raman
and parametric amplifiers are also addressed. Since the first
fiber-based parametric amplifier experiments providing net
continuous-wave gain in the for the optical fiber communication
applications interesting 1.5-μm region were only conducted about two
years ago, there is reason to believe that substantial progress may be
made in the future, perhaps involving "holey fibers" to further enhance
the nonlinearity and thus the gain. This together with the emergence of
practical and inexpensive high-power pump lasers may in many cases prove
fiber-based parametric amplifiers to be a desired implementation in
optical communication systems
The objective of this thesis is to investigate the suitability of fibre optical parametric amplifiers (FOPAs) for use in multi-channel, dynamic networks. First, we investigate their quasi-static behaviour in such an environment. We study the behaviour of a FOPA under realistic conditions and we examine the impact on the gain spectrum of channel addition for several different operating conditions and regimes. In particular, we examine the impact of surviving channel(s) position, input power and channel spacing. We see how these parameters affect the gain tilt as well as its dynamic characteristics, namely the generation of under or over-shoots at the transition point, possible dependence of rise and fall times on any of the aforementioned parameters and how the gain excursions depend on those parameters. For these studies we assume continuous wave operation for all signals. We observe that the gain spectrum changes are a function of the position and the spacing of the channels. We also find that the gain excursion can reach several dBs (up to 5 dB) in the case of channel add/drop and are heavily dependent on the position of the surviving channels. The channels located in the middle of the transmission band are more prone to channel add/drop-induced gain changes. Moreover, we investigate for the first time the FOPA dynamic behaviour in a packet switching scenario. This part of the study assumes that all but one channels normally vary in a packet-switched fashion. The remaining channel (probe channel) is expected to undergo gain variations due to the perturbation of the system experienced by the other channels. Furthermore, we consider several different scenarios for which the channels spacing, per channel input power (PCIP), variance of the power fluctuation and position of the probe channel will change. We find that when the FOPA operates near saturation the target gain is not achieved more than 50% of the time while the peak-to-peak gain excursions can exceed 1 dB. Next, we introduce modulated channels to the amplifier in order to compare their effect on the Bit Error Rate (BER) performance. We consider the impact on FOPAs when employing different modulation formats, such as RZ, NRZ and RZ-DPSK. Carefully selected modulation formats can improve BER performance and reduce the effects of cross-phase modulation, four wave mixing (FWM) products generation or dispersion (non-linear and linear inter-channel interference). Especially for the case of FOPAs, because of the ultra-fast interaction times of the FWM phenomenon, cross gain modulation can be a great deterrent for using FOPAs. We use RZ-DPSK in order to suppress the WDM signal crosstalk. Only by using RZ-DPSK, we obtain an improved receiver sensitivity of 5 dB when operating at 40 Gb/s. Finally, we investigate ways to mitigate such effects as the ones described above (gain excursions, gain tilt etc.). We demonstrate that by using a ring configuration with optical feedback for the first time in FOPAs, we can achieve all-optical gain clamping (AOGC), mitigating gain excursions and attaining gain, independent of channel input power for a large range of PCIP. For example, with the use of AOGC, we reduce the add/drop-induced gain excursions from 4 dB to 0.6 dB. Also, by the combined use of AOGC and RZ-DPSK, we mitigate most of the aforementioned hindrances described above. L'objectif de cette thèse est d'explorer l'utilité des amplificateurs paramétriques à fibre optique (APFO) à l'intérieur de réseaux dynamiques à canaux multiples.Tout d'abord, nous investiguons le comportement quasi-statique des amplificateurs dans un tel environnement. Nous étudions le comportement d'un APFO dans des conditions réalistes et nous examinons l'impact de l'addition de canaux sur le spectre d'amplification sous plusieurs conditions d'opération. En particulier, nous examinons l'impact de la position du canal survivant, de la puissance initiale et de l'espace des canaux. Nous présentons comment ces paramètres affectent l'inclinaison du spectre d'amplification ainsi que sa dynamique, incluant la présence de dépassements et de sous-dépassements au point de transition, la dépendance possible des temps de monté et de descentes sur les paramètres mentionnés précédemment et comment l'amplification varie selon ces paramètres. Pour ces études nous assumons une opération continue pour tous les signaux. Nous observons que les changements au spectre d'amplification se produisent en fonction de la position et de l'espacement des canaux. Nous remarquons aussi que la variation d'amplification peut atteindre plusieurs dB (jusqu'à 5 dB) dans le cas de l'ajout ou de la suppression de plusieurs canaux et qu'elle dépend lourdement de la position des canaux survivants. Les canaux situés au centre de la bande de transmission sont plus susceptible aux variations d'amplification due à l'ajout ou à la suppression d'autres canaux.De plus, nous étudions pour la première fois le comportement dynamique d'un APFO dans un réseau où il y a commutation par paquets. Cette portion de l'étude assume que tous les canaux sauf un varient selon une distribution Gaussienne. Le canal restant devrait subir des variations d'amplification du aux perturbations causé par les autres canaux. Nous considérons aussi plusieurs scénarios différents pour lesquels l'espacement des canaux, leur puissance initiale, la variance des fluctuations de puissance et la position du canal de test changent. Nous observons que lorsque l'APFO fonctionne près du point de saturation l'objectif d'amplification est atteint moins que 50% du temps et que les variations d'amplification peuvent dépasser 1 dB.Ensuite, nous utilisons des canaux modulés avec différentes techniques (RZ, NRZ et RZ-DPSK) à fin de comparer leur impact sur le taux d'erreur des bits. Sélectionner le format de modulation optimal améliore le taux d'erreur et réduit les effets de modulation d'amplification croisée, de mélange à quatre ondes et la dispersion. À cause des temps d'interaction très rapide des effets de mélange à quatre ondes, la modulation d'amplification croisée peut être très problématique lors de l'utilisation de APFOs. Nous employons une modulation RZ-DPSK pour éliminer la diaphonie entre les canaux. En utilisant la RZ-DPSK, nous obtenons une augmentation de la sensibilité du récepteur de 5 dB en opérant à 40 Gb/s.Finalement, nous étudions des moyens de réduire les effets mentionnés ci-dessus. Nous démontrons pour la première fois dans des APFOs qu'en utilisant une configuration en anneau avec une contre-réaction optique nous pouvons obtenir un calage d'amplification tout-optique (CATO), réduire les variations d'amplifications et réaliser une amplification constante et indépendante de la puissance initiale. Par exemple, avec l'utilisation de CATO, nous réduisons les variations d'amplification de 4 dB à 0.6 dB. De plus, en combinant le CATO et la RZ-DPSK, nous diminuons grandement la plupart des effets indésirables mentionnés précédemment.
Binary-phase-shift-keyed pump modulation in fiber parametric devices is investigated. The temporal and spectral properties of wavelength-converted optical signals are studied as functions of the pump-modulation rate. Excessive idler broadening is observed in both one- and two-pump parametric architectures. The idler impairments are found to increase as the rise and fall times of the pump-modulation scheme decrease.
We report that pump-noise induced four-wave mixing effects can be serious for some nonzero dispersion-shifted fiber using distributed Raman amplification. Moreover, we find that such an effect strongly depends on the spectral structure of the pump, and can be suppressed by expanding the effective spectral width of the pump.
