Title :
Investigation of Graphene Dispersion From Kelly Sideband in Stable Mode-Locked Erbium-Doped Fiber Laser by Few-Layer Graphene Saturable Absorbers
Author :
Hou-Ren Chen ; Chih-Ya Tsai ; Ching-Yang Chang ; Kuei-Huei Lin ; Chen-Shiung Chang ; Wen-Feng Hsieh
Author_Institution :
Dept. of Photonics, Nat. Chiao Tung Univ., Hsinchu, Taiwan
Abstract :
In this paper, stable passively mode-locked fiber lasers (MLFLs) constructed using graphene saturable absorbers (SAs) with different layer numbers of ~1 to ~15 have been reported. The flat linear transmission spectrum in the range from 1540 to 1580 nm without any distinct absorption peak implies that the graphene SAs exhibit low dispersion in this region. Therefore, stable soliton-like pulses are generated because of negative dispersion provided by the fiber laser cavity, which requires no additional single-mode fiber (SMF) for dispersion compensation. Power-dependent transmission measurements show that the saturation intensity ranges from 1.2 to 3.2 MW/cm2 and that the modulation depth (MD) of the graphene SAs increases with the number of graphene layers. All the samples were observed to easily mode-lock the laser with a stable mode-locking state persistently operated over hours. By analyzing the soliton Kelly sidebands, we deduced the group delay dispersion (GDD) for different layers of the graphene. The calculated results show that the variation of sample GDD is within the calculation error, indicating that the GDD of graphene is small to be negligible. This result is consistent with the experimental results reported by Chang et al. [Appl. Phys. Lett. 97, 211102 (2010)] using the phase-shift method. This study demonstrates that different layers graphene SAs have different MD contributions to the generation of laser pulses with different pulse widths.
Keywords :
erbium; fibre lasers; graphene; infrared spectra; laser cavity resonators; laser mode locking; laser stability; optical fibre dispersion; optical modulation; optical pulse generation; optical saturable absorption; optical solitons; C; dispersion compensation; few-layer graphene saturable absorbers; fiber laser cavity; flat linear transmission spectrum; graphene dispersion; graphene layer number; group delay dispersion; laser pulse generation; modulation depth; negative dispersion; phase-shift method; power-dependent transmission measurements; pulse widths; saturation intensity; soliton Kelly sidebands; stable passively mode-locked erbium-doped fiber lasers; stable soliton-like pulse generation; wavelength 1540 nm to 1580 nm; Amplitude modulation; Cavity resonators; Films; Graphene; Optical fiber dispersion; Optical fibers; Fiber lasers; laser mode-locking; nanomaterials; ultrafast optics;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2015.2471100