We demonstrated an all fiber actively mode-locked laser that emits a cylindrical vector beam. An intra-cavity few-mode fiber Bragg grating inscribed in a short section of four-mode fiber is employed to provide mode selection and spectrum filtering functions. Mode coupling is achieved by offset splicing between the single-mode fiber and the four-mode fiber in the laser cavity. A ${\mathrm{LiNbO}}_3$ Mach–Zehnder modulator is used to achieve active mode-locking in the laser. The laser operates at 1547 nm with 30 dB spectrum width of 0.2 nm. The mode-locked pulses have a duration of 2 ns and repetition of 12.06 MHz. Through adjusting the polarization state in the laser cavity, both radially and azimuthally polarized beams have been obtained with high mode purity.

We demonstrate a novel all-fiber laser generating cylindrical vector beams with high slope efficiency and low threshold by introducing a long-period fiber grating into the laser cavity. Highly efficient mode conversion is realized by an LPFG at $\sim 1548\mathrm{nm}$. Mode selection and spectrum filtering are achieved in combination with a two-mode fiber Bragg grating (TM-FBG). The fiber laser operates at a single wavelength of 1547.95 nm with a 30 dB linewidth of less than 0.18 nm and a side-mode suppression ratio (SMSR) of more than 56 dB. The lasing threshold and slope efficiency of the laser are 24.5 mW and 35.41%, respectively. The output power is 72 mW with an absorbed pump power of 225 mW. The variation of slope efficiency with respect to the reflectivity of the TM-FBG is investigated. Through adjusting the intra-cavity polarization controller, high-purity radially and azimuthally polarized beams are both obtained.

We proposed a resolution enhanced integral imaging display method using two micro-lens arrays (MLA) with different focal lengths for capturing and display respectively. An elemental image array (EIA) is captured with MLA of focal length of f₁ and a processed EIA is displayed with MLA of focal length of f₂ which is larger than f₁. We enlarge the “effective area” in processed EIA to increase the information obtained by viewer, in other words, enhance the viewing resolution. The two micro-lens arrays for capturing and display are g and mg distant from display device respectively, and we can get m² times resolution enhancement.

We demonstrate a new method to detect the vortex beams carrying orbital angular momentum by a sectorial screen. When the sectorial screen is illuminated by optical vortex beams, the far-field diffraction pattern can be used to visually determine the modulus and sign of topological charges. We also prove that center alignment is not strictly required. The experimental results agree well with the simulated results.

We demonstrate an all fiber passively mode-locked laser emitting a radially polarized beam by using a few-mode fiber Bragg grating to achieve mode selection and spectrum filtering. An offset splicing of single-mode fiber with four-mode fiber is utilized as a mode coupler in the laser cavity. Carbon nanotubes are introduced into the laser cavity as the saturable absorber to achieve self-start mode locking. The laser operates at 1547.5 nm with a narrow spectrum width of 0.3 nm at 30 dB. The emitted mode-locked pulses have a duration of 22.73 ps and repetition of 10.61 MHz. A radially polarized beam has been obtained with high mode purity by adjusting the polarization in the laser cavity.