Impact Of Phase Modulation Research Articles

Impact of phase modulation and parametric gain on signal polarization in an anomalously dispersive optical fiber

We theoretically and experimentally study changes with pump power in the polarization of an optical signal as it simultaneously experiences Kerr-effect-induced birefringence and four-wave-mixing-based parametric amplification from a copropagating pump in an optical fiber. It is shown that the changes caused by the two nonlinear optical effects are orthogonal to each other in the Stokes space. Results also show that the pump polarization state works as an attractor for signal polarization. The implications of this feature to fiber parametric amplifiers and entangled-photon sources are discussed, and a fiber polarization switch is demonstrated.

Impact of phase modulation and filter characteristics on dual-pumped fiber-optical parametric amplification

We have derived theory predicting the impact phase modulation has on dual-pumped parametric amplifiers which includes also the effect of pump power fluctuations. The theory shows that gain perturbations due to perturbations in the pump frequencies can be significantly reduced by operating the two pumps out of phase. Furthermore, filtering the phase-modulated pumps can introduce detrimental gain variations and we propose the use of "flat-top" filter characteristics in order to reduce the filter bandwidths around the pump without causing too much gain-variations on the amplified signal. We also investigate the effect of detuned optical filters.