▎ 摘　　要

As the oxide-induced disruption from silicon dioxide substrate would greatly decrease the thermal property of graphene, strategies to optimize the thermo-optical response through controlling laser spot size, layer number and covering length of graphene layer are experimentally studied and discussed. An all-optical controlled fiber Mach-Zehnder interferometer with multilayer and monolayer graphene achieved by thermo-optical effects is subsequently proposed to prove the improvements. Graphene layers with 6 mm length were transferred to the middle taper and heated by an external laser. The maximum switching extinction ratio reached 16.2 dB. The response time and modulation efficiency were approximately 620 mu s and 0.22 dB mW(-1), respectively. This work suggests an effective way to improve the thermal property of graphene-fiber hybrid structure for all-optical control in fiber based integrated system. Moreover, the cost and complexity of device manufacturing are greatly reduced.