Symmetry breaking and intensity switching of counterpropagating Raman waves in a microresonator.

We experimentally demonstrate symmetry breaking, symmetry restoring, and intensity switching of counterpropagating Raman waves in a microresonator with symmetric intracavity waves at the pump frequency. Stationary symmetric and asymmetric states of Raman waves are theoretically found within a symmetric system of equations, and asymmetric branches of solutions turned out to be unstable. To explain the experimental results, it is proposed that there is a weak asymmetry in the system that radically changes the system behavior, which has been confirmed by numerical simulations.

Polarization squeezing in chalcogenide fibers.

We experimentally demonstrate the generation of polarization-squeezed light in a short piece of solid-core chalcogenide (ChG) (AsS) fiber via the Kerr effect for femtosecond pulses at 1.56 µm. Directly measured squeezing of -2.

Role of the inverse Čerenkov effect in the formation of ultrashort Raman solitons in silica microspheres.

We theoretically demonstrate a new regime, to the best of our knowledge, of the formation of ultrashort optical solitons in spherical silica microresonators with whispering gallery modes. The solitons are driven by a coherent CW pump at the frequency in the range of normal dispersion, and the energy is transferred from this pump to the solitons via two channels: the Raman amplification and inverse Čerenkov effect. We discuss three different regimes of soliton propagation and we also show that these Raman solitons can be controlled by weak coherent CW signals.

Bidirectional Raman soliton-like combs with unidirectional pump in a spherical microresonator.

We experimentally demonstrate bidirectional Raman soliton-like combs in a whispering gallery mode microresonator with a unidirectional pump for the first time, to the best of our knowledge. We develop a relatively simple theoretical model and find an analytical solution for forward- and backward-propagating Raman sech-shaped solitons in an anomalous dispersion region under unidirectional pumping in a normal dispersion region. Raman solitons exist, thanks to the balance between losses and Raman gain from a CW wave (which is equal in both directions) as well as between dispersion and Kerr nonlinearity.

Ultra-broadband frequency shifting of laser pulses in a square multicore chalcogenide fiber.

The process of Raman frequency shifting of out-of-phase laser pulses in fibers with a square configuration of weakly coupled cores having two or more zero dispersion wavelengths has been studied. The use of out-of-phase distributions in multicore fibers makes it possible to increase pulse energies by orders of magnitude in comparison with the case of single-core fibers. Conditions for the stability of out-of-phase laser pulses are determined and confirmed by numerical simulations.