Passive Q -Switching with Erbium-Doped Fiber Laser Using Titanium Dioxide Colloid as a Saturable Absorber

We successfully demonstrate a Q -switched erbium-doped fiber laser (EDFL) using titanium dioxide (TiO 2 ) coated onto a fiber ferrule as a saturable absorber (SA). The fiber ferrule is immersed into a TiO 2 colloid, using the dip-coating method to prepare the SA. Stable pulses operating at 1,565 nm with a 3 dB bandwidth of 1.9 nm are achieved within the pump power range from 63.41 to 104.62 mW. A maximum repetition rate of 72.89 kHz and a pulse energy of 29.91 nJ are respectively generated, while the minimum pulse width is 3.02 μs. To the best of our knowledge, this is the first demonstration of EDFL passive Q -switching using TiO 2 colloid.