Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.
A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.
Graduate Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, No 1, Sec 4, Roosevelt Road, Taipei 106, Taiwan, China.
Yung-Hsiang
YH
Lin
Chun-Yu
CY
Yang
Jia-Hong
JH
Liou
Chin-Ping
CP
Yu
Gong-Ru
GR
Lin
D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006108:Graphite / Q000737:chemistry* / Q000528:radiation effects; D007834:Lasers; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D036103:Nanotechnology / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
D006108:Graphite