Titania-coated silica nanocomposite for L-band noise-like pulse fiber laser

A nanocomposite of titania-coated silica saturable absorber (TiO2-SiO2-SA) was fabricated via alkaline fusion and spin-coating. The TiO2-SiO2-SA possessed nonlinear saturable absorption and optical limiting effect with 30.35% modulation depth, 42.57 mu J/cm(2) saturation fluence, and 0.0075 cm(2)/mu J two-photon absorption coefficient. By designing a ring cavity erbium-doped fiber laser in net normal dispersion regime and TiO2-SiO2-SA as mode-locker, a stable noise-like pulse (NLP) at 1.57 mu m with similar to 21 nm spectral bandwidth was initiated at low threshold power of 22.6 mW, and maintained its operation at maximum pump power of 234 mW. A pulse spike of 587 fs riding on 4.47 ps pulse pedestal at 7.66 MHz repetition frequency confirmed its NLP regime. The generated NLP with TiO2-SiO2-SA was very stable and estimated damage threshold of at least 786 mu J/cm(2) pumping fluence suggest its potential as one of next generation nanocomposite materials for ultrafast photonics.

Automated summary

A nanocomposite of titania-coated silica saturable absorber (TiO2-SiO2-SA) with nonlinear saturable absorption and optical limiting effect was fabricated. It demonstrated stable noise-like pulse (NLP) generation in a ring cavity erbium-doped fiber laser at low threshold power and maintained operation at high pump power. The NLP with TiO2-SiO2-SA showed stability and potential as a next-generation nanocomposite material for ultrafast photonics.