Passively Q-switched erbium-doped fiber laser based on carbon nanotube saturable absorber

Abstract

In the field of laser technology, fiber lasers have developed rapidly because of its high power or energy. Q-switching technique has been widely used in fiber lasers to produce laser pulse. Here we demonstrate a passively Q-switched erbiumdoped fiber laser using a single-walled carbon nanotubes (SWCNTs) saturable absorber. The SWCNTs were fabricated by a new sol-gel method and placed onto the tip of a fiber ferrule. A TIWDM device replaced wavelength division multiplexer, isolation and tap to reduce the loss of the laser. Since only the evanescent field of the propagating light interacts with SWCNTs in saturable absorber, the fiber laser can maintain a relatively high intra-cavity power. As the pump power increasing, the output performance of the laser continues to improve. Laser center wavelength is 1560nm. An output pulse with energy of 70.9nJ is obtained with a repetition rate of 15.4 kHz and pulse width of 3.6 μs.