Visible Pulse Fiber Laser Oscillation Properties Enhanced by Improved Transcription Method of Graphene Saturable Absorber Mirror

Abstract

Improved transcription method of graphene saturable absorber mirror (GSAM) is tested to enhance visible pulse fiber laser oscillation properties. When a graphene thin film on a dielectric multi-layered mirror is soaked in nitric acid solution for washing process, the mirror suffers from a deterioration of transmission spectrum, or a detachment of dielectric multilayer from a mirror substrate. New method is the way that a dielectric multi-layered mirror is not washed in nitric acid directly and the transcribed graphene on a silica glass sheet is just put on a dielectric multi-layered mirror with opponent situation. Visible pulse laser oscillation in a Pr-doped double-clad structured waterproof fluoride glass fiber was tested with two types of GSAM whose dielectric multilayered parts are directly (GSAM-I) or not directly (GSAM-II) washed in nitric acid solution. The maximum output average power with GSAM-II was measured to be 9.52 mW at 644 mW GaN-LD excitation, on the other hand, 2.63 mW for GSAM-I and the slope efficiency of GSAM-II one was also improved as four times as GSAM-I one. Therefore, it is considered that the new washing process of transcribed graphene is effective for keeping the mirror properties and enhancement of the laser properties.