Kelly sideband variation and self four-wave-mixing in femtosecond fiber soliton laser mode-locked by multiple exfoliated graphite nano-particles
Journal
Laser Physics Letters
Journal Volume
10
Journal Issue
4
Date Issued
2013
Author(s)
Lin, Y.-H.
Abstract
An imprinting–exfoliation–wiping method is demonstrated to reduce the number of layers of graphite nano-particles and create a femtosecond passively mode-locked erbium doped fiber laser (EDFL). As the number of exfoliations increases from 1 to 7, the linear transmittance of the graphite nano-particle increases from 0.44 to 0.9, and the modulation depth increases from 22% to 57%. Moreover, the 2D band of the graphite nano-particles in the Raman spectrum becomes intense and symmetric, which indicates the structural properties of the graphite nano-particles approach those of few-layer graphene. The passively mode-locked EDFL pulsewidth reduces from 755 to 375 fs as the number of exfoliations increases from 1 to 7, while the spectral linewidth broadens from 3.55 to 6.85 nm. The first-order Kelly sideband on the optical spectrum is observed with a frequency spacing Dυ decreasing from ±1.45 to ±1.35 THz. The frequency spacing of the second-order Kelly sideband decreases slightly from ±2.04 to ±2.01 THz on increasing from six to seven applications of the imprinting–exfoliation–wiping process. Apart from the Kelly sidebands, two spectral peaks arise on the soliton spectrum with the six-times exfoliated graphite nano-particles due to the nonlinear four-wave-mixing (FWM) effect of Kelly sidebands during propagation in the EDFL cavity.
Type
journal article