We propose and demonstrate a compact all-fiber laser generating cylindrical vector beam (CVB) using carbon nanotubes as the saturable absorber for mode-locking and a two-mode fiber Bragg grating (TM-FBG) as the mode discriminator. Both radially and azimuthally polarized beams with a polarization purity of 90% were obtained by simply adjusting the polarization controllers. The CVB mode-locked fiber laser operates at 1552.9 nm with a 3-dB line width of less than 0.02 nm, generating ns CVB pulses. The all-fiber CVB laser may have potential applications from fundamental research to practical applications, such as particle capture, high-resolution measurement and material processing.
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This work was supported by National Science Foundation of Jiangsu Province under
Grants BK20161521 and BK20150858; Nanjing University of Posts and Telecommunications (NUPTSF) under
Grants NY214059, NY214002, and NY215002; Distinguished Professor Project of Jiangsu under Grant
RK002STP14001; Six Talent Peaks Project in Jiangsu Province under Grant 2015-XCL-023; Postgraduate
Research & Practice Innovation Program of Jiangsu Province under Grants SJ