The Features Of Nonlinear Optics Of Graphene And Its Application In Fiber Laser

Ultrashort pulse sources are widely used in the field of industry processing,nonlinear optical frequency conversion, bio-photonics, spectroscopy, medical, smartsensor networks, and communication. In this thesis, the newly developednano-material----graphene is introduced into the fiber laser as saturable absorber togenerate Q-switched and mode-locked optical pulses. The theoretical andexperimental research contents are included as following.1. The spatial structure and energy level structure features are analyzed. Therelationship of fine structure constant and the absorption of graphene are discussed.The characteristics of different layer graphene are analyzed.2. The graphene saturable absorbers are fabricated. By dispersing grphene powderinto the organic solvents, the even-distributed graphene solution is made. Thedifferent films of saturable absorber samples are fabricated on the end facets of fiberby the method of optically driven deposition. By transferring monolayer graphenefilm onto fiber end facet, the monolayer graphene saturable absorber sample is made.3. The Raman spectrum of self-made graphene film samples are analyzed byexperiments. The purity, thickness and uniform properties of samples are ascertained.The graphene layers are coated in two quartz glasses by the method of spin coating.By use of infrared spectroscopy to get the transmittance spectrum of the two quartzglasses, the linear absorption properties of the graphene film as saturable absorber isresearched. The nonlinear optical absorption property of the graphene film sample isstudied by the Z-scan experiment.4. The graphene saturable absorber passively Q-switched fiber laser is investigatedexperimentally. The different output characteristics of passively Q-switched fiberlasers based on two self-made graphene film saturable absorbers with differentthickness are researched by inserting the graphene saturable absorbers into thepassively Q-switched fiber laser cavities.5. The graphene based passively mode-locked fiber laser is experimental analyzed.The stable passively mode-locked pulses are generated by constructing a graphenesaturable absorber passively mode-locked fiber laser. Increasing the EDFA power incavity, the passively harmonic mode-locking pulses are observed. Decreasing ofintensity of the laser cavity by increasing the ratio of output coupler, the passivelyharmonic mode-locked pulses are restrained. 6. The monolayer graphene based Er/Yb co-doped double-claded passivelymode-locked fiber laser is researched by experiment. By introducing a self-mademonolayer graphene saturable absorber into a Er/Yb co-doped double clad fiber laser,the stable mode-locked pulses are obtained. The output characteristics of the fiberlaser are researched experimentally.