Wavelength-switchable all-fiber laser-emitting radially polarized beams.

We present two kinds of mode-selective-coupler-based ultrafast radially polarized lasers delivering switchable wavelengths and pulsewidths. One is a linear-cavity fiber laser mode locked in the 1.5 µm region, which produces not only wavelength-agile radially polarized pulses in the spatial domain, but also switchable femtosecond and picosecond pulses in the temporal domain. The other one is a nonlinear-polarization-rotation-technique-assisted passively mode-locked fiber ring laser in the 1.0 µm region, presenting an ideal broadband spectral switching with picosecond radially polarized pulses output. The presented fiber lasers offer a type of compact laser source, enabling a flexible option for radially polarized beams in spectral and temporal domains.