All-fiber radially/azimuthally polarized lasers based on mode coupling of tapered fibers

Abstract

We demonstrate a mode converter with an insertion loss of 0.36 dB based on mode coupling of tapered single-mode and two-mode fibers, and realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution of a tangential electric field at taper boundaries, the laser is switchable between the radially and azimuthally polarized states by adjusting the input polarization. In the temporal domain, the operation is controllable among continuous-wave, Q-switched, and mode-locked statuses by changing the saturable absorber or pump strength. The duration of Q-switched radially/azimuthally polarized laser spans from 10.4/10.8 to 6/6.4 μs at the pump range of 38 to 58 mW, while that of the mode-locked pulse varies from 39.2/31.9 to 5.6/5.2 ps by controlling the laser bandwidth. The proposed laser combines the features of a cylindrical vector beam, a fiber laser, and an ultrafast pulse, providing a special and cost-effective source for practical applications.

Mode and Wavelength-Switchable Pulsed Fiber Laser With Few-Mode Fiber Grating

“…Therefore, it is critical to investigate fiber lasers with high-order mode emission, especially switchable dual-mode (fundamental and higher order modes) operation. Manuscript Besides being used for MDM transmission, few-mode fiber (FMF) has also important applications in mode manipulation through FMF-based devices, such as fiber taper [3,4], coupler [5][6][7][8], and grating [9][10][11]. Taking fiber Bragg grating as an example, since each mode of FMF is independent and has different propagation constant, the few-mode fiber Bragg grating (FM-FBG) can reflect different modes accommodated by the grating's phase matching condition and determined by the FMF spatial distribution.…”

Structured Light from Lasers

“…Controlling the chirality of light remains a topical subject. An obvious case of vector vortex beams is the generation of radially and azimuthally polarized beams, particularly from fiber lasers . Once again, many approaches have been explored to create such modes including radially polarized LG modes by annular pumping, radially polarized arbitrary structured ring and arc beams with an intracavity axicon, as shown in Figure , and vector flat‐top beams …”

A High‐Efficiency All‐Fiber Laser Operated in High‐Order Mode using Ring‐Core Yb‐Doped Fiber

“…[], few‐mode fiber Bragg grating (FMFBG) can be used as an ideal reflector and mode selector in all‐fiber CVB lasers. Thus, all‐fiber CVB lasers have been widely studied through combining FMFBG and mode excitation elements, such as offset splice spot and mode‐selective coupler . However, those lasers are inefficient due to the limitation of conversion efficiency and insertion loss of the mode excitation element.…”