Passively Q-Switched EDFL Using a Multi-Walled Carbon Nanotube Polymer Composite Based on a Saturable Absorber

A stable passive Q-switched erbium-doped fiber laser (EDFL) operating at 1563.5 nm is demonstrated by using a multi-walled carbon nanotube (MWCNT) polymer composite film based saturable absorber for the first time. The composite is prepared by mixing the MWCNTs homogeneous solution into a dilute PEO polymer solution before it is left to dry at room temperature to produce thin film. Then the film is sandwiched between two FC/PC fiber connectors and is integrated into the laser cavity for Q-switching pulse generation. The EDFL generates a stable pulse train with repetition rates ranging from 4.5 kHz to 20.0 kHz by varying the 1480 nm pump power from 35 mW to 53 mW. At the 53 mW pump power, the pulse width and pulse energy are 8.8 μs and 15.3 nJ, respectively.