Carbon Nanotube- Polyvinylalcohol Composite Film as Nonlinear Optical Device: Application to Femtosecond Mode-Locked Fiber Laser

Saturable absorption of single-wall carbon nanotubes (SWNTs) in near-infrared region [1] is very promising as a passive mode-locker for pico- or subpicosecond pulsed Er-doped fiber lasers [2]. In this work, we fabricated SWNT/polyvinylalcohol (PVA) nanocomposite self-standing films [3] for saturable absorption devices, and used as a mode-locker for Er-doped fiber short pulse lasers. We integrated a 35-$\mu $m-thick SWNT/PVA composite film into a conventional FC/PC fiber connection adaptor, where the film is sandwiched by a pair of fiber ferrules. A ring cavity fiber laser inserted with the SWNT/PVA saturable absorber operated very easily in mode-locked short pulse mode with a pulse width as short as 210 fs, which, to our knowledge, is the shortest in this class of lasers using carbon nanotube saturable absorbers. This result demonstrates that the SWNT/PVA composite film is very promising as a passive mode-locker for femtosecond Er-doped fiber lasers. [1] Y. Sakakibara et al.: Jpn. J. Appl. Phys. 42 (2003) L494. [2] S. Y. Set et al.: OSA Trends in Optics and Photonics Vol.86, Optical Fiber Commun. Conf., Tech. Dig., Postconf. Ed., pd44. [3] A. G. Rozhin et al.: Thin Solid Films 464-465 (2004) 368.