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Atomic‐Layer Graphene as a Saturable Absorber for Ultrafast Pulsed Lasers
Author(s) -
Bao Qiaoliang,
Zhang Han,
Wang Yu,
Ni Zhenhua,
Yan Yongli,
Shen Ze Xiang,
Loh Kian Ping,
Tang Ding Yuan
Publication year - 2009
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200901007
Subject(s) - graphene , materials science , saturable absorption , ultrashort pulse , optoelectronics , laser , fiber laser , mode locking , graphene nanoribbons , optics , nanotechnology , wavelength , physics
The optical conductance of monolayer graphene is defined solely by the fine structure constant, α = $e^2 /\hbar c$ (where e is the electron charge, $\hbar $ is Dirac's constant and c is the speed of light). The absorbance has been predicted to be independent of frequency. In principle, the interband optical absorption in zero‐gap graphene could be saturated readily under strong excitation due to Pauli blocking. Here, use of atomic layer graphene as saturable absorber in a mode‐locked fiber laser for the generation of ultrashort soliton pulses (756 fs) at the telecommunication band is demonstrated. The modulation depth can be tuned in a wide range from 66.5% to 6.2% by varying the graphene thickness. These results suggest that ultrathin graphene films are potentially useful as optical elements in fiber lasers. Graphene as a laser mode locker can have many merits such as lower saturation intensity, ultrafast recovery time, tunable modulation depth, and wideband tunability.