Christopher G. Goedde

LONG-TERM STORAGE OF A SOLITON BIT STREAM BY USE OF PHASE-SENSITIVE AMPLIFICATION

We propose long-term storage of a soliton bit stream in a fiber ring in which loss is compensated by phase-sensitive amplification. We show that the 1s (soliton pulses) are asymptotically stable and that the noise on the 0s of the bit stream (absence of a soliton) is bounded. Moreover, the soliton-soliton interaction is efficiently suppressed by the phase-sensitive amplifiers.

Stabilizing dark solitons by periodic phase-sensitive amplification

We show that dark solitons are stabilized with respect to amplitude variations when phase-sensitive amplification and spectral filtering are used in combination to compensate for linear loss. In particular, we show that spectral filtering inhibits the sideband instabilities typical of nonlinear pulses and cw waves in periodically amplified systems, whereas phase-sensitive amplification inhibits the destabilization of the constant-intensity background wave caused by the filtering.

Increased Stokes pulse energy variation from amplified classical noise in a fiber Raman generator.

We present an experimental and theoretical study of the transition from linear to nonlinear amplification of classical pump noise in a fiber Raman generator. In particular, we focus on the conversion of fluctuations in the fine temporal structure of Q-switched pump pulses into Stokes pulse energy fluctuations. We show that there is a distinct pump power domain where large scale fluctuations in the Stokes pulse energy result from the amplification of fluctuations in the temporal structure of pump pulses with stable energies. Dramatic changes in the shape of the Stokes pulse energy probability distribution also occur as the pump power is swept through the domain of large scale energy fluctuations.

Compensation of the soliton self-frequency shift with phase-sensitive amplifiers.

We analyze the effect of Raman scattering and higher-order dispersion on the propagation of short (1-ps) pulses in a nonlinear optical fiber in which the loss is balanced by a periodic chain of phase-sensitive, degenerate parametric amplifiers. The analysis shows that the Raman scattering does not induce a continuous frequency downshift on the pulse but only a small, finite frequency shift. Pulse propagation is governed by a nonlinear fourth-order evolution equation that admits stable solutions that propagate with a small, constant, inverse velocity in the group-volocity rest frame.

Periodic amplification and conjugation of optical solitons

Nondegenerate optical parametric amplifiers can be used to simultaneously phase conjugate and amplify a pulse in a nonlinear optical fiber. The gain in the amplifiers compensates the linear loss in the fiber, while the phase conjugation effectively neutralizes second-order dispersion, self-phase modulation, the Raman self-frequency shift, and Gordon-Haus jitter. If the remaining third-order and nonlinear dispersions balance, solitonlike pulses are able to propagate with subpicosecond pulse widths.

Influence of classical pump noise on long-pulse multiorder stimulated Raman scattering in optical fiber

We present a combined experimental and theoretical study of the effect of pump pulse noise on the growth and statistics of multiorder stimulated Raman scattering in optical fiber. Because of the intensity dependence of stimulated Raman scattering, fluctuations in the detailed temporal structure of the pump pulse amplitude strongly affect the growth and statistics of the Stokes orders, even when dispersive effects are not important. By comparing experimental results with a detailed model including the frequency dependence of the Raman gain and the pump pulse temporal structure, we show that the pump pulse temporal fluctuations play a pivotal role in determining the growth and pulse energy statistics of the Stokes orders.

Periodically conjugated solitons in dispersion-managed optical fiber

Abstract We present an analysis of long-distance propagation for short optical solitons in a nonlinear optical fiber incorporating the effects of periodic phase conjugation and dispersion management. The analysis includes the Raman self-frequency shift, third-order dispersion, and nonlinear dispersion. The periodic conjugation compensates for the group velocity dispersion, self-phase modulation and Raman self-frequency shift; we show that stable pulse propagation results from the the balance of the (negative) third-order dispersion and the nonlinear dispersion. Judicious choice of the dispersion map negates perturbations due to linear loss; the analysis predicts parameters for the dispersion map that minimize pulse distortion.

Long-term storage of a soliton bit stream using phase-sensitive amplification: effects of soliton–soliton interactions and quantum noise

Abstract We analyze the long-term stability properties of a soliton bit stream stored in a fiber ring in which linear loss is compensated by phase-sensitive amplification. The analysis and numerical computations presented here model the effects of soliton–soliton interactions, pulse timing and amplitude fluctuations induced by quantum noise, and phase noise caused by guided acoustic-wave Brillouin scattering. We show that phase-sensitive amplification significantly enhances the storage rings stability properties, so that the ones (the soliton pulses) are asymptotically stable and that the noise on the zeros of the bit stream (i.e., where solitons are absent) is bounded. The soliton–soliton interactions and noise-induced pulse timing jitter are substantially reduced by phase-sensitive amplification. Finally, we demonstrate that by adding a relatively small amount of modulation to the pump pulses that drive the amplifiers, it is possible to eliminate all of the residual pulse interactions and timing jitter.

Effects of pump pulse temporal structure on long-pulse multi-order stimulated Raman scattering in optical fiber

We present an experimental and theoretical investigation of the effects of pump pulse temporal structure on cascade Raman generation in the quasi-continuous wave regime. The growth and saturation of the Stokes pulse energies depend very strongly on the pump pulse temporal envelope and substructure. Experiments and simulations on the growth of the total Stokes pulse energy and the energy in a narrow central slice highlight the importance of knowing the detailed pump pulse temporal structure. Experimentally measured growth curves for different Stokes orders could be transformed by a simple scaling to lie on a universal curve.