Fig. 1. Schematic diagram of fiber-based STED nanolithography setup. (HWP, half wave plate; QWP, quarter wave plate; DM, dichroic mirror; L, lens; SMF, single-mode fiber; BFG, Bragg fiber grating; LPG, long-period grating; PC, polarization controller.)

Fig. 2. (a) Intensity and polarization distributions of 1030 nm input laser in front of the vortex fiber (the ellipses represent the direction of polarization). (b) Intensity and polarization distributions of 1030 nm output laser behind the fiber tail. Spectra of 1030 nm laser (c) in front of and (d) behind the fiber.

Fig. 3. Pulse sequences of 1030 nm laser (a) in front of and (b) behind the fiber. (c) Pulse width of excitation beam.

Fig. 4. (a) Output 532 nm laser after passing through a linear polarizer with different transmission axis orientations. (b) Intensity and polarization distributions of 532 nm laser behind the fiber tail.

Fig. 5. (a) Simulated depletion beam PSF in the xy plane of the focal region. (b) Focus amplification system (BS, beam splitter; L, lens; M, mirror). (c) Experimentally measured focused depletion beam PSF.

Fig. 6. (a) Simulated excitation beam PSF and (b) relationship between the FWHM of the effective beam and the power of the depletion beam in the xy plane of the focal region. (c) Intensity distribution of the effective beam in the xy plane of the focal region under different depletion beam powers.