Passively mode-locked fiber laser based on single-walled carbon nanotube and graphene as co-saturable absorbers

Abstract

Ultrashort pulse sources are important in the field of industry processing. With its excellent linear and nonlinear optical characteristics, graphene and single-walled carbon nanotubes(SWCNTs) have been proven to be two attractive materials to generate nanosecond, picosecond and femtosecond laser pulses. They have a lot of advantages, such as lower saturation intensity, larger saturable-absorption modulation depth, higher damage threshold, sub-picosecond recovery time. Graphene and SWCNTs were deposited on the fiber end facets by the optically driven deposition method. By utilizing two different staurable absorbers, we study the performance of three different lasers. Two Er-doped Q-switched optical fiber lasers were constructed by constructing graphene and SWCNTs separately into the ring cavity as saturable absorber. Different performances of the two fiber lasers were investigated by the physical characteristics of the two different materials. Stable pulses generated by a passively mode-locked fiber laser was obtained when two saturable absorbers were inserted into the resonator cavity of a fiber laser at the same time, the repetition rate of 8 MHz which agree with the length of the cavity proved the mode-locked state of the laser. This first time ever trial shows excellent output properties for its long time stable operation.