Gain Of Fiber Optical Parametric Amplifier Research Articles

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.

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.

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.

Optimizing bandwidth of fiber optical parametric amplifier with different combinations of higher-order dispersion coefficient signs

This paper investigates the influence of different combinations of second-order (β2 ), fourth-order (β4 ) and sixth-order (β6 ) dispersion coefficient signs (negativity/positivity) to the fiber optical parametric amplifier gain performance. The numerical simulation has exploited the fourth-order Runge-Kutta method to solve the coupled amplitude equations which basically represent the parametric process of four-wave mixing. In the normal regime at which β2 is positive, the fiber optical parametric amplifier exhibits a poor gain spectrum and it is well performed once the pump is presumed to be in anomalous regime i.e. β2 is negative. The effect of β4 is significant when the signal wavelength is further from the pump wavelength and a wide amplification bandwidth is produced when the fiber have positive β4 in the anomalous regime. As for β6 , unfortunately in this simulation its influences are hardly can be seen probably because of its small value regardless its sign, but, from phase-mismatch equation it is shown that its impact is prominent when the signal is positioned way far from the pump. All in all, this shown that the signs combination of the higher-order dispersion coefficients are significant in order to optimize the FOPA amplification bandwidth.

Dynamic Control of Gain Profile in Fiber-Optical Parametric Amplifier by Gain-Transparent SBS

We propose and experimentally demonstrate dynamic control of gain profile in a single-pump fiber-optical parametric amplifier (FOPA) assisted by gain-transparent stimulated Brillouin scattering. The FOPA gain can be enhanced/reduced through controlling the phase-matching condition without disturbing the initial parameters of the FOPA. Both the maximum and minimum gain profiles are obtained, offering operational flexibility in randomly synthesizing the profile to satisfy different requirements. Our synthesis can turn the conventional M-shaped profile into spectrally flat gain with 0.1-dB variation over 24 nm. This scheme can be potentially applied to dual-pump FOPA and can benefit other applications of parametric processes.

Gain enhancement of fiber optical parametric amplifier via introducing phase-shifted fiber Bragg grating for phase matching

The gain enhancement properties of a fiber optical parametric amplifier (FOPA) are investigated by inserting a phase-shifted fiber Bragg grating (PS-FBG) between two highly nonlinear dispersion shift fibers (HNL-DSFs). The PS-FBG is adopted to reduce the power and change the phase of the idler wave, and thus to change the phase mismatch parameter and relative phase difference among the four involved waves in four-wave mixing (FWM). The influence of reflectivity and phase shift of the PS-FBG on the gain properties of FOPA is focused on. It is shown that, with the introduction of PS-FBG, the gain of FOPA is enhanced significantly. With the increase of reflectivity of PS-FBG, the gain increases first and reaches its maximum at the optimal reflectivity. Besides, the π-phase shift contributes to the highest gain of FOPA. The effect of insertion loss is also considered. The FOPA with PS-FBG provides a new tool to obtain gain enhancement, which is extremely useful for the optical communication system.

Influence of Raman effect on the noise characteristics in a dual pump FOPA

Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier (FOPA) is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are firstly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure (NF).

Optimization of Raman-Assisted Fiber Optical Parametric Amplifier Gain

We studied the gain of Raman-assisted fiber optical parametric amplifiers (RA-FOPAs) both theoretically and experimentally. We investigated the relationship between the overall gain and different combinations of Raman and parametric pump powers using contour maps. We derived a normalized phase-matched model to determine the general behavior the peak gains of RA-FOPAs operating in the small signal region. The contour maps of the combined gain enhancement can be used to optimize both indirect and direct Raman gain of the signal/idler in RA-FOPAs. We showed that, in a given fiber, it is possible to optimize the Raman and parametric pump powers in RA-FOPAs for high gain and high efficiency.

Brillouin Optical Time-Domain Analysis of Fiber-Optic Parametric Amplifiers

We carried out distributed measurements of the longitudinal gain of fiber-optical parametric amplifiers using a novel sensing technique based on Brillouin optical time-domain analysis. Using this technique, we successfully characterized different gain behaviors in the linear and the saturation regimes. In addition, we demonstrated the recently predicted gain reciprocity at opposite ends of the amplifier span

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.