In-line phase-sensitive amplification of multi-channel CW signals based on frequency nondegenerate four-wave-mixing in fiber.

We demonstrate phase-sensitive amplification of multiple wavelength-division-multiplexed continuous-wave (CW) signals by frequency nondegenerate four-wave-mixing process in optical fiber. By fine-tuning the optical wavelengths of the CW signals, simultaneous phase-sensitive in-line amplification of three signal channels is realized. This indicates the possibility of amplifying multiple data channels by an in-line phase-sensitive fiber parametric amplifier. We also discuss a potential system architecture employing such amplifiers.

Probabilistic model of nonlinear penalties due to collision-induced timing jitter for calculation of the bit error ratio in wavelength-division-multiplexed return-to-zero systems.

We introduce a fully deterministic, computationally efficient method for characterizing the effect of nonlinearity in optical fiber transmission systems that utilize wavelength-division multiplexing and return-to-zero modulation. The method accurately accounts for bit-pattern-dependent nonlinear distortion due to collision-induced timing jitter and for amplifier noise. We apply this method to calculate the error probability as a function of channel spacing in a prototypical multichannel return-to-zero undersea system.

Asymptotic analysis of collision-induced timing shifts in return-to-zero quasi-linear systems with predispersion and postdispersion compensation.

An asymptotic method for calculating the collision-induced frequency and timing shifts for quasi-linear pulses in return-to-zero, wavelength-division multiplexed systems with predispersion and postdispersion compensation is developed. Predictions of the asymptotic theory agree well with quadrature and direct numerical simulations. Using this theory, computational savings of many orders of magnitude can be realized over direct numerical simulations.

Calculation, characterization, and application of the time shift function in wavelength-division-multiplexed return-to-zero systems.

We calculate the time shift function for collisions of pairs of pulses in different channels in a prototypical return-to-zero wavelength-division-multiplexed system with dispersion management and precompensation and postcompensation. Once the time shift function is known, the impairments that are due to collision-induced timing jitter can be rapidly determined. We characterize the shape of this function and determine how it scales with the initial pulse separation in time and with channel separation in wavelength. Finally, we apply it to the calculation of the worst-case time shift.

10-GHz dispersion-managed soliton fiber-optical parametric oscillator using regenerative mode locking.

We demonstrate a regeneratively mode-locked fiber-optical parametric oscillator that utilizes intracavity dispersion compensation to generate pulses at a 10-GHz repetition rate in both soliton and nonsoliton regimes. At the threshold pump power the generated pulses are close to fundamental solitons. At higher pump powers we found a significant deviation of the pulses from the sech2 shape. In addition, the use of an ultralow-jitter self-starting pump-pulse source in a regenerative feedback loop allows for a significant reduction of the signal's timing jitter and amplitude noise.

Gain characteristics of a frequency nondegenerate phase-sensitive fiber-optic parametric amplifier with phase self-stabilized input.

We experimentally demonstrate, for the first time to our knowledge, a phase-sensitive amplifier based on frequency nondegenerate parametric amplification in optical fiber, where the input signal-idler pair is prepared all-optically. Using two fiber-optic parametric amplifier sections separated by a fiber-based wavelength-dependent phase shifter, we observe and investigate phase-sensitive gain profile in the 1550 nm region both experimentally and theoretically. The realized scheme automatically generates gain-defining phase that is environmentally stable, making it advantageous for building phase-sensitive transmission links.