Fiber Optical Parametric Amplifier Research Articles

Temperature control of the gain spectrum of fiber optical parametric amplifiers

The gain spectrum of a fiber optical parametric amplifier (OPA) can be controlled by imposing a temperature distribution along the fiber, which modulates the local fiber zero-dispersion wavelength lambda0, and hence the parametric gain coefficient. We present simulations and experimental verification for various binary temperature distributions. The method should be applicable to fibers with realistic longitudinal variations of lambda0.

Tunable all optical delay via slow and fast light propagation in a Raman assisted fiber optical parametric amplifier: a route to all optical buffering

We propose and demonstrate the use of narrow band optical parametric amplification for tunable slow and fast light propagation in optical fibers. The parametric gain is coupled to the Raman process which changes the gain value moderately but modifies the gain spectral shape. Consequently, the delay is enhanced at short wavelengths while it is moderated at long wavelengths. The maximum delay and tuning range can be optimized with respect to each other considering saturation effects in long fibers. The proposed scheme offers tunable delay in the presence of gain and with a bandwidth which is sufficiently wide to process digital data streams at tens of Gbit/s rates as well as picoseconds pulses.

Impact of pump phase modulation on system performance of fibre-optical parametric amplifiers

Bit error rate induced in a parametric amplifier has been measured with a 10 Gbit/s line rate. It is shown experimentally that the phase modulation of the pump distorts the mark level of the channel and may cause system penalty. Different phase modulation schemes have been compared.

Measurement of the photon statistics and the noise figure of a fiber-optic parametric amplifier: erratum

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Paul L. Voss, Renyong Tang, and Prem Kumar, "Measurement of the photon statistics and the noise figure of a fiber-optic parametric amplifier: erratum," Opt. Lett. 29, 2815-2815 (2004) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Noise-figure limit of fiber-optical parametric amplifiers and wavelength converters: experimental investigation

Recent theoretical work predicts that the quantum-limited noise figure of a x(3)-based fiber-optical parametric amplifier operating as a phase-insensitive in-line amplifier or as a wavelength converter exceeds the standard 3-dB limit at high gain. The degradation of the noise figure is caused by the excess noise added by the unavoidable Raman gain and loss occurring at the signal and the converted wavelengths. We present detailed experimental evidence in support of this theory through measurements of the gain and noise-figure spectra for phase-insensitive parametric amplification and wavelength conversion in a continuous-wave amplifier made from 4.4 km of dispersion-shifted fiber. The theory is also extended to include the effect of distributed linear loss on the noise figure of such a long-length parametric amplifier and wavelength converter.

Influence of zero dispersion wavelength variations on cross-talk in single-pumped fiber optic parametric amplifiers

We show that variations of the zero dispersion wavelength (λ0) in single-pumped fiber optic parametric amplifiers (FOPAs), greatly enhances four-wave mixing induced cross-talk in a two-channel wavelength division multiplexed system. We compare experimentally the performance of two FOPAs with identical gains but differing in their standard deviations of λ0 (∼0.1 and ∼2 nm) and we obtain a power penalty of 3.8 dB larger in the FOPA with the larger fluctuations of λ0.

Toward Practical Fiber Optical Parametric Amplifiers and Oscillators

Advances in fiber optical parametric amplifiers (OPAs) may lead to practical applications in areas that include optical communications and high-power wavelength conversion.

Wide-Band Tuning of the Gain Spectra of One-Pump Fiber Optical Parametric Amplifiers

By suitably choosing the fiber properties, and by tuning the pump wavelength near the fiber zero-dispersion wavelength, one can in principle generate a wide variety of one-pump fiber optical parametric amplifier gain spectra. These can range from a very wide single region to two symmetric narrow gain regions far away from the pump. We have experimentally verified these predictions. With a highly nonlinear fiber, we have inferred the existence of gain over a single 400-nm region and measured a maximum on-off gain of 65 dB. With a common dispersion-shifted fiber, we have obtained tunable gain regions less than 1 nm wide, up to 200 nm from the pump; we have also shifted these by several nanometers by lowering the fiber temperature to 0/spl deg/C.

Design of Fiber-Optical Parametric Amplifiers by Genetic Algorithm

Genetic algorithm is adopted to give an automatic design scheme for fiber-based optical parametric amplifiers (FOPAs). Main steps of the optimization process and discussion about this algorithm are presented. The results show that present FOPA has more than 300-nm flat bandwidth with a central wavelength of 1500 nm and a gain ripple of less than 0.3 dB. Meanwhile, fluctuation in zero-dispersion wavelength of fibers is taken into consideration and its influence is briefly analyzed.

Vector theory of four-wave mixing: polarization effects in fiber-optic parametric amplifiers

We present a vector theory of four-wave mixing and use it to study the polarization-dependent nature of four-wave mixing and the conditions under which the gain of a dual-pump fiber-optic parametric amplifier becomes polarization independent. We find that in the absence of self- and cross-phase modulations, any pair of orthogonally polarized pumps can provide polarization-independent gain, but this gain is minimum for linearly polarized pumps and becomes maximum when the two pumps are circularly polarized. Self-and cross-phase modulations induce nonlinear polarization rotation and change the orthogonality between the two pump polarizations. We discuss the general case of elliptically polarized cases and show that only linearly and circularly polarized pumps can maintain their orthogonality along the fiber. A stability analysis shows that the case of linearly polarized pumps is more stable than the circular one against small deviations from the ideal case but that the latter provides much more amplification.

Impact of Pump Phase Modulation on the Gain of Fiber Optical Parametric Amplifier

In practice, fiber optical parametric amplifiers are generally driven by a phase-modulated pump wave to avoid stimulated Brillouin back-scattering. We show both analytically and numerically that the phase modulation of the pump can induce strong parametric gain modulation and that this detrimental effect depends both on the rise-fall time of the phase modulator and on the fiber dispersion slope.

Impact of Dispersion Fluctuations on Dual-Pump Fiber-Optic Parametric Amplifiers

Effects of zero-dispersion wavelength (ZDWL) fluctuations on dual-pump fiber-optic parametric amplifiers are investigated analytically and numerically. It is found that the signal gain varies considerably from fiber to fiber even though each fiber may have the same ZDWL on average. Moreover, the gain spectrum becomes highly nonuniform for a given fiber because of such dispersion fluctuations. Numerical simulations show that this problem can be solved to a large extent by reducing wavelength separation between the two pumps, but only at the expense of a reduced amplifier bandwidth.

Design strategy for controlling four-wave mixing-induced crosstalk between channels in a fibre optical parametric amplifier

The four-wave mixing-induced crosstalk has been investigated in fibre parametric amplifiers. The required gain (and conversion efficiency) can be obtained by increasing fibre nonlinearity, fibre length or pump power. In each case, crosstalk is generated, however new results are presented that demonstrate that crosstalk in a fibre parametric amplifier is minimised by using a design with the highest possible pump power and a short fibre with low nonlinearity. For the parameters considered, the crosstalk in an amplifier with 20 dB of gain can be reduced by as much as 18 dB. Conversely, results are presented that demonstrate that crosstalk can be maximised, as is desirable when using parametric processes for signal reshaping, optical limiting or dispersion monitoring applications. For increasing channel counts the crosstalk is found to initially increase and then tends towards saturation.

Simultaneous S + -band amplification and S + –C-band wavelength conversion in CW pumped fibre optic parametric amplifier

The operation of a continuous-wave (CW) single-wavelength pumped fibre optic parametric amplifier operating in the S/sup +/-band with simultaneous wavelength conversion to the C-band is demonstrated. Peak gain of 25 dB at 1518 nm and gains higher than 10 dB from 1510 to 1530 nm were obtained using 480 m of a fibre with a nonlinear coefficient /spl gamma/=12.2 W/sup -1/ km/sup -1/, requiring a pump power of 660 mW. Simultaneously, idler wavelengths were generated in the C-band with a peak conversion efficiency of 25 dB at 1552 nm.

Noise Characteristics of Fiber Optical Parametric Amplifiers

We derive an analytical theory for the noise figure of an undepleted and lossless fiber optical parametric amplifier (FOPA). Both the signal and the wavelength converted idler are investigated. Our theory is applicable for both an ideal pump power source, as well as a noisy one. We find that a noisy pump source can severely degrade the performance at high gain due to the stochastic gain-variations the signal and idler will experience. The theory is compared with Monte Carlo simulations of the FOPA and an excellent agreement is obtained. Simulations in the gain-depleted region show the possibility to reach below quantum-limited, phase-insensitive amplification for single channel transmission.

Spurious Four-Wave Mixing in Two-Pump Fiber-Optic Parametric Amplifiers

We present an experimental study on four-wave mixing (FWM) between two signals within a two-pump fiber-optical parametric amplifier (2P-FOPA). We demonstrate that the intensity of FWM spurious tones depend strongly on the signal power and length of the nonlinear medium and present two regimes as a function of the pumps' power. We also compare the amounts of FWM as a function of channel spacing in the 2P-FOPA with or without pumps and show that the presence of parametric gain enhances FWM over a broad spectral range.

Raman-Generated Pump Impact on Optical Parametric Amplification

Continuous-wave (CW) Raman-generated pump impact on a fiber optical parametric amplifier (OPA) is analyzed. Different noise contributions associated to the pump are experimentally and theoretically evaluated. Gain and noise figure of the amplifier are presented and commented for different OPA configurations. By tightly filtering the CW Raman-generated pump an OPA noise figure approaching the 3 dB limit is achieved.

Optimized design of two-pump fiber optical parametric amplifier with two-section nonlinear fibers using genetic algorithm

A new two-pump fiber optical parametric amplifier (FOPA) is presented, which is composed of two-section high nonlinear fibers (HNLFs). Genetic algorithm (GA), a multivariate stochastic optimization algorithm is applied to optimize parameters of two fiber segments, such as the length and dispersion coefficient of fiber. A broadband FOPA with twosection HNLFs is obtained using optimum design parameters, which theoretically provides a uniform gain of 20.3 dB with 0.2-dB uniformity over a 346-nm bandwidth.

Extremely simple device for measuring 1.5-�m ultrashort laser pulses

We have demonstrated an experimentally very simple and sensitive GRENOUILLE device for measuring the intensity and phase vs. time and spatio-temporal distortions of 100-fs to few-ps 1.5-microm pulses using the nonlinear-optical crystal Proustite. We show that the dispersive and nonlinear-optical characteristics of Proustite are critical for achieving very simple and reliable measurements of such pulses from fiber lasers and optical parametric amplifiers.

Fiber optical parametric amplifiers with linearly or circularly polarized waves

We introduce a formalism that provides a unified solution for the gain spectrum of fiber optical parametric amplifiers (OPAs) using either linearly or circularly polarized waves. There are 12 basic types, including five that have not been previously investigated to our knowledge. We provide a simple method for calculating the maximum gain and nonlinear phase mismatch for such OPAs. All these OPAs have similar elliptical graphs for parametric gain versus propagation constant mismatch, with a width equal to four times the height. This implies that, when fiber dispersion is taken into account, any two-pump OPA can be used to obtain the same gain spectrum as any other OPA in the same fiber, provided that the pump power is adjusted for equal maximum gain and that real solutions exist for the resulting equation for the required pump spacing. In that sense, all these fiber OPAs form an equivalence class.