P. Ferro

Modulational instability in second-harmonic generation.

We show that the eigenmodes of the two-wave interaction in a dispersive quadratic medium are unstable with respect to periodic perturbations. This mechanism represents a novel kind of modulational instability that involves the spontaneous generation of sideband pairs around both the fundamental and the second-harmonic frequencies.

Multiple soliton bound states and symmetry breaking in quadratic media

We present a study of the dynamics of multiple soliton bound states in diffractive media with second-order nonlinearity. A numerical stability analysis of these bound states reveals that wave propagation in quadratic materials exhibits spatial symmetry-breaking instabilities.

Polarization switching in spun birefringent fiber

We have experimentally observed the relatively low‐power self‐switching of polarization ellipticity along the profile of initially circularly polarized picosecond pulses in a spun birefringent fiber. The switching and pulse breakup effects originate from the intensity‐dependent modulation of the birefringence beat length.

Phase control of a nonlinear coherent coupler: The multi‐beat‐length twisted birefringent fiber

We demonstrate that the switching power in a multi‐beat‐length and mismatched nonlinear coherent coupler may be controlled by means of a small variation of the relative phase of two equally intense input beams.

DEMONSTRATION OF NONLINEAR NONRECIPROCITY AND LOGIC OPERATIONS WITH A TWISTED BIREFRINGENT OPTICAL FIBER

The uniform twist of the birefringence axes of an optical fiber introduces a nonlinear nonreciprocity into power-dependent polarization switching characteristics. We experimentally demonstrate the nonreciprocity of a ten-beat-length-long twisted low-birefringence fiber that permits all-optical logic operations with orthogonal circularly polarized input pulses.