106μm Q-switched ytterbium-doped fiber laser using few-layer topological insulator Bi_2Se_3 as a saturable absorber

TLDR

The few‑layer Bi₂Se₃ topological insulator was fabricated by liquid‑phase exfoliation, optically deposited onto a fiber ferrule, and exhibited a low saturable intensity of 53 MW cm⁻², forming a fiber‑integrated saturable absorber. Using this absorber, a 1.06 µm ytterbium‑doped fiber laser produced stable Q‑switching with 1.95 µs pulses, 17.9 nJ energy, and a tunable repetition rate of 8.3–29.1 kHz, confirming the TI’s wavelength‑independent saturable‑absorber capability.

Abstract

Passive Q-switching of an ytterbium-doped fiber (YDF) laser with few-layer topological insulator (TI) is, to the best of our knowledge, experimentally demonstrated for the first time. The few-layer TI: Bi2Se3 (2-4 layer thickness) is fabricated by the liquid-phase exfoliation method, and has a low saturable optical intensity of 53 MW/cm2 measured by the Z-scan technique. The optical deposition technique is used to induce the few-layer TI in the solution onto a fiber ferrule for successfully constructing the fiber-integrated TI-based saturable absorber (SA). By inserting this SA into the YDF laser cavity, stable Q-switching operation at 1.06 {\mu}m is achieved. The Q-switched pulses have the shortest pulse duration of 1.95 {\mu}s, the maximum pulse energy of 17.9 nJ and a tunable pulse-repetition-rate from 8.3 to 29.1 kHz. Our results indicate that the TI as a SA is also available at 1 {\mu}m waveband, revealing its potential as another wavelength-independent SA (like graphene).