We propose and demonstrate, for the first time to the best of our knowledge, a passively mode-locked ytterbium-doped fiber laser generating cylindrical vector beams (CVBs) using a mode selective coupler (MSC) as the transverse mode converter and splitter, and a semiconductor saturable absorber mirror (SESAM) for mode-locking. According to the coupling mode theory and the phase matching principle, the MSC was fabricated by weakly fused technology, having a low loss of about 0.5 dB and achieving LP11 mode with a high purity of > 96%. The CVB fiber laser operates at a center wavelength of 1042.3 nm, with a 3 dB spectral width of 1.5 nm. The repetition rate of the mode-locked laser pulses is 18.58 MHz. The radially and azimuthally polarized vector beams can be switched by adjusting the polarization controllers in the fiber ring cavity, with a high mode purity measured to be > 95%. The mode-locked CVB ytterbium-doped fiber laser has potential applications in optical tweezers, optical imaging, and so on.
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Funding: This work was supported by National Science
Foundation of Jiangsu Province under (BK20150858, BK20161521), the
Distinguished Professor Project of Jiangsu (RK002STP14001), the Talents
Projects in Nanjing University of Posts and Telecommunications (NY214002,
NY215002) and the STITP of NUPT (XZD2017040).
- Cylindrical vector beam
- laser mode locking
- mode selective coupler