Unimpaired phase-sensitive amplification by vector four-wave mixing near the zero-dispersion frequency.

Phase-sensitive amplification (PSA), which is produced by degenerate four-wave mixing (FWM) in a randomly-birefringent fiber, has the potential to improve the performance of optical communication systems. Scalar FWM, which is driven by parallel pumps, is impaired by the generation of pump-pump and pump-signal harmonics, which limit the level, and modify the phase sensitivity, of the signal gain. In contrast, vector FWM, which is driven by perpendicular pumps, is not impaired by the generation of harmonics. Vector FWM produces PSA with the classical properties of a one-mode squeezing transformation.

Stokes-space derivations of generalized Schrodinger equations for wave propagation in various fibers.

In this report, multiple-scale analysis (averaging) is used to derive the generalized Schrödinger equations that govern light-wave propagation in strongly-birefringent, randomly-birefringent and rapidly-spun fibers. The averaging procedures are described in Jones space and Stokes space. Despite the differences between the aforementioned fibers, the Stokes-space procedures associated with them are similar, and involve only quantities whose physical significances are known. Not only does the Stokes-space formalism unify the derivations of the aforementioned Schrödinger equations, it also produces equations directly in Jones-Stokes notation, which facilitates subsequent studies of polarization effects in optical systems.

Four-wave mixing in a rapidly-spun fiber.

In a previous paper the generalized Schroedinger equation that governs wave propagation in a rapidly-spun fiber was derived. In this paper the aforementioned equation is used to study four-wave mixing (FWM). The properties of FWM associated with a rapidly-spun fiber are described, and contrasted to those associated with constantly-birefringent and randomly-birefringent fibers. FWM driven by perpendicular linearly-polarized pump waves, or counter-rotating circularly-polarized pump waves, provides polarization-independent signal amplification and phase-conjugation, whereas FWM driven by co-rotating circularly-polarized pump waves provides polarization-independent frequency conversion.