Distributed characterization of localized and stationary dynamic Brillouin gratings in polarization maintaining optical fibers.

We experimentally generate localized and stationary dynamic Brillouin gratings in a 5 m long polarization maintaining fiber by phase-modulation of the pumps with a pseudo-random bit sequence. The dynamic Brillouin gratings are characterized in terms of length, bandwidth, group delay and group delay ripple, optical signal-to-noise ratio and peak to sidelobe ratio by measuring the distribution of the complex reflected signal along the fiber through swept-wavelength interferometry. By numerical processing, the performance of an optimal modulation format enabling null off-peak reflections are estimated and compared to the pseudo-random bit sequence case.

Experimental analysis of degenerate vector phase-sensitive amplification.

We comprehensively investigate a degenerate vector phase-sensitive amplifier (PSA). We determine the gain dependence on the relative phase and polarization angle between the pumps and the degenerate signal wave. The vector PSA is experimentally shown to be sensitive to the pump states of polarization (SOP) due to polarization mode dispersion in the fiber. However, the scheme performance agrees well with theory under specific pump SOPs and we achieve an on-off gain over 10 dB with a small deviation from the theoretically expected results. In comparison to the scalar scheme, the proposed vector scheme has larger tolerance for pump depletion due to four-wave mixing between pumps and generation of higher-order idlers.

Widely time-dispersion-tuned fiber optical oscillator and frequency comb based on multiple nonlinear processes.

An all-fiber optical oscillator based on three nonlinear processes, namely stimulated Raman scattering and broad-band and narrow-band optical parametric amplification, is presented and experimentally characterized. The wavelength tuning is achieved by means of the time-dispersion technique and spans over 160 nm. Through the same technique a fast tunable optical frequency comb has been realized exploiting cascaded four-wave mixing.

Experimental characterization of the counter-propagating Raman polarization attraction.

Recently, fiber Raman amplifiers have proven to be effective in the all-optical control of the state of polarization of signals in single-mode telecommunications optical fibers. Previous works predicted the existence of a quantitative relationship between the achieved degree of polarization and the mean Raman gain. Here, we experimentally validate such a relationship in the case of counter-propagating Raman-based polarization attractors for different pump and signal powers and for different fiber link lengths.