Abstract
•A spin-coating technique of black phosphorous/polymer composite is proposed.•Optimization of spin-coating and microfiber parameters are studied and proposed.•Incorporation of black phosphorous/polymer saturable absorber in a fiber laser.•Ultrashort pulse of less than 800 fs is generated at 1560 nm wavelength.
Numerous saturable absorber (SA) fabrication methods have been proposed and employed in the development of ultrafast laser systems, particularly for microfiber-based SAs decorated with various 2D materials. However, the study on microfiber-SA with different transition lengths is still inadequate. This paper focuses on the design and fabrication method of black phosphorus/polydimethylsiloxane composite microfiber-based SA for ultrashort pulse generation. With optimized microfiber-SA dimensions of 30 mm (up/down taper), 1 mm (waist length) and 10 µm (waist diameter), black phosphorus/polydimethylsiloxane composite was spin-coated on the microfiber at 4000 rpm for 6 min. The integration of the microfiber-SA in an erbium-doped fiber laser exhibited pulse duration of 724 fs at center wavelength of 1560.18 nm. This work provides a guideline for the design of microfiber-based SA using spin-coating technique to maximize its laser performances.