Theoretical design of a single-mode fiber-based bi-order Bessel beam for a STED system

Abstract

Stimulated emission depletion (STED) microscopy has attracted great research attention due to its applications to breaking diffraction limits for imaging and lithography. However, its implementation based on single-mode fibers often encounters challenges such as complex structural integration, costly fabrication processes, and the need for specific fiber designs. Herein, a low-cost bi-order Bessel beam based on one single-mode fiber integrated with a structurally simple wavelength-scale microstructure (WSM) on fiber end was proposed for STED system. Through simulation study for full-scale WSM optimization, we have successfully developed a bicolor laser beam (BLB) consisting of a zero-order Bessel beam at a wavelength of 405 nm and a donuts high-order Bessel beam at a wavelength of 532 nm. This fiber-based configuration allows us to achieve a diffraction-limited spot size with a working distance of 0.67λpump and a minimum FWHM of 0.395λpump. By combining wavelength division multiplexing technology with power modulation of the donuts beam, this work provides a promising way for achieving super-resolution imaging or lithography with only one single-mode fiber.