No abstract

Multi-wavelength lasers have widespread applications (e.g. fiber telecommunications, pump-probe measurements, terahertz generation). Here, we report a nanotube-mode-locked all-fiber ultrafast oscillator emitting three wavelengths at the central wavelengths of about 1540, 1550, and 1560 nm, which are tunable by stretching fiber Bragg gratings. The output pulse duration is around 6 ps with a spectral width of ~0.5 nm, agreeing well with the numerical simulations. The triple-laser system is controlled precisely and insensitive to environmental perturbations with <0.04% amplitude fluctuation. Our method provides a simple, stable, low-cost, multi-wavelength ultrafast-pulsed source for spectroscopy, biomedical research and telecommunications.

We propose a plasmonic nanosensor based on Fano resonance in the strong-confinement metal-dielectric-metal waveguide side-coupled with a pair of nanoresonators. Due to the coherent interference of the splitting discrete and quasi-continuum modes, the reflection spectrum possesses a sharp asymmetric Fano resonance dip, which is dependent on the cavity-cavity phase and the refractive index change of the dielectric. The physical features contribute to a highly efficient plasmonic sensor for refractive index sensing. The nanosensor yields a sensitivity of ~900 nm/RIU and a figure of merit of ~500, remarkable values compared with those of plasmonic sensors supported by perfect absorbers.

A novel ultrafast all-optical switching based on metal-insulator-metal nanoplasmonic waveguide with a Kerr nonlinear resonator is proposed and investigated numerically. With the finite-difference time-domain simulations, it is demonstrated that an obvious optical bistability of the signal light appears by varying the control-light intensity, and an excellent switching effect is achieved. This bistability originates from the intensity-dependent change induced in the dielectric constant of Kerr nonlinear material filled in the nanodisk resonator. It is found that the proposed all-optical switching exhibits femtosecond-scale feedback time.