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ABSTRACT The aim of this article is to report the fabrication and characterization of dispersed multiwalled carbon nanotubes (MWCNTs) polymer composites and use them as passive SAs in Q-switched Erbium-doped fiber (EDF) for ultrafast laser generation at 1.5-µm region. CNT polymer composites were fabricated into thin films by homogenizing different concentrations (1.8, 4.8, and 10.1 wt. %) of MWCNTs with host polymers polyethylene oxide. The fabricated thin film was then deposited between two fiber connectors as passive SA and incorporated into fiber laser's ring oscillator. The EDFL exhibited a central wavelength of 1560.5 nm when pump power is fixed at 42 mW. The Q-switching operation starts at the lowest threshold of 39.3 mW for all the three different SA concentrations. For 1.8 wt. % MWCNTs concentration, the pulse repetition rate of the Q-switched EDFL is started from 35.6 kHz, while for 4.8 wt. % and 10.1 wt. %, the pulse repetition rate started at 78.5 and 66.1 kHz, respectively. At the MWCNTs concentration of 1.8 wt. %, the pulse energy of the Q-switched EDFL increases from 7.9 to 24.7 nJ as the pump power increases from 39.3 to 58.8 mW. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1897-1901, 2015 [ABSTRACT FROM AUTHOR]

We demonstrate a simple, compact and low-cost mode-locked erbium-doped fiber laser (EDFL) using a single- wall carbon nanotube (SWCNT) poly-ethylene oxide (PEO) composite as a passive saturable absorber (SA). The composite with an SWCNT concentration of 18wt% is prepared by mixing the SWCNT homogeneous solution with a diluted PEO polymer solution. A droplet of the polymer composite is applied on the fiber ferrule end, which is then mated to another clean ferrule connector to construct an SA. The SA is then integrated into the laser system to self-start stable mode locking at 1557nm without employing a polarization controller. The EDFL generates a stable soliton pulse train with a duration of 0.81 ps, repetition rate of 44 MHz and average output power of 92.4 μW at a 980nm pump power of 26.8mW. The soliton laser starts to lase at a pump power threshold of 14.6 mW. [ABSTRACT FROM AUTHOR]