Optics (physics.optics)

Abstract: Ultrafast all-fiber Yb-doped fiber oscillators are usually associated with all-normal-dispersion cavities, which operate in a dissipative soliton regime, quintessential for pulsed operation at the wavelength of 1 {\mu}m. This work presents an all-polarization-maintaining Yb-doper fiber laser oscillator that operates in a dispersion-managed dissipative soliton regime, thanks to incorporating a chirped fiber Bragg grating. The oscillator, mode-locked via a nonlinear optical loop mirror, has an unconventional semi-linear cavity of net anomalous dispersion. Unlike in standard ring resonators, the ultrashort pulse undergoes amplification twice per cavity roundtrip. Additionally, we report a duality of pulsed operation states depending on the pumping power. Strikingly, the oscillator can work in a~subregime similar to the standard dissipative soliton, facilitating further energy scaling at anomalous dispersion. We characterize the low-noise setup capable of delivering pulse energy as high as 6.4 nJ using standard single-mode polarization-maintaining optical fibers.

Abstract: We study the existence and stability of $\pi$-solitons on a ring of periodically oscillating waveguides. The array is arranged into Su-Schrieffer-Heeger structure placed on a ring, with additional spacing between two ends of the array. Due to longitudinal oscillations of waveguides, this Floquet structure spends half of the longitudinal period in topological phase, while on the other half it is nontopological. Nevertheless, waveguide oscillations lead to the emergence of anomalous topological $\pi$-modes at both ends of the structure that strongly couple in our ring geometry, leading to the formation of previously unexplored in-phase and out-of-phase $\pi$-modes. We study topological solitons bifurcating from such linear $\pi$-modes and demonstrate how their properties and stability depend on the size of the ring and on spacing between two ends of the array.

Abstract: The use of nanophotonics for optical manipulation has continuously attracted interest in both fundamental research and practical applications, due to its significantly enhanced capabilities at the nanoscale. In this work, we showed that plasmonic particles can be trapped at off-axis location in Gaussian beams assisted by surface plasmon resonance. The off-axis displacement can be tuned at the sub-wavelength scale by the incident light beams. Based on these, we propose that a superfast orbital rotation of particles in continuous-wave laser beam can be realized in tightly focused circularly polarized Gaussian beams. The rotation has a tunable orbital radius at the sub-wavelength scale and a superfast rotation speed (more than 10^4 r/s in water under common laboratory conditions). Our work will aid in the development of optically driven nanomachines, and find applications in micro/nano-rheology, micro-fluid mechanics, and biological research at the nanoscale.