Uni-directional wavelength conversion in silicon using four-wave mixing driven by cross-polarized pumps.

We demonstrate optical frequency conversion between telecom wavelengths using four-wave mixing Bragg scattering powered by two pump pulses polarized on orthogonal axes of a silicon waveguide. This allows conversion in a single frequency direction while, with co-polarized pumps, the signal is redshifted or blueshifted with similar efficiency. Our approach exploits the birefringence of the waveguide and its effect on the phase matching of the four-wave mixing process.

Enhancement of out-of-band rejection in optical filters based on phase-sensitive amplification.

We present a novel optical filter based on amplification and deamplification in a phase-sensitive amplifier (PSA), whose out-of-band rejection is enhanced by slightly imbalancing the inputs to the PSA. The out-of-band rejection of the PSA-based filter with balanced input signal and idler powers is given by G in the optical domain, where G is the maximum phase-sensitive gain. By unbalancing the input to the PSA, the optical out-of-band rejection is significantly enhanced beyond G, thus enabling filters with high rejection even with moderate-gain PSAs.

Four-wave-mixing cascades near the zero-dispersion frequency.

Exact formulas are obtained for the amplitudes of light waves involved in four-wave-mixing cascades near the zero-dispersion frequency of a fiber. The cascade that is initiated by two strong pump waves is phase insensitive, whereas the cascade that is initiated by two strong pump waves and a weak signal wave is phase sensitive. In both cascades, the number of waves that have significant power increases with distance.

Collision-induced time shift of a dispersion-managed soliton and its minimization in wavelength-division-multiplexed transmission.

The formula for the time shift of a dispersion-managed soliton that results from its collision with other solitons in different channels consists of two terms, one related to the frequency shift during collision, and the other related to the residual frequency shift after collision. It is found that an optimal relative delay exists between pulses in adjacent channels after each dispersion-managed span that balances the contributions from the two terms and minimizes the overall time shift, leading to a substantial improvement in transmission performance.