▎ 摘　　要

NOVELTY - The sensor has a standard single mode fiber, a standard multimode fiber, and a tin oxide layer doped with graphene. The standard multimode fiber and the standard single mode fiber has the same cladding diameter. The standard multimode fiber has a larger core diameter than standard single mode fiber. The standard multimode fiber (MM), standard single mode fiber (SM), and standard multimode fiber are sequentially welded. The axes of the three portions of the optical fibers are on the same line after the welding. The surface of the standard single mode fiber is coated with a tin oxide layer doped with graphene. The standard single mode fiber is the sensing area. The organic solvent is different propyl alcohol, the tin source is Tin(IV) chloride pentahydrate. USE - Graphene-based core mismatched optical fiber sensor used for environmental monitoring and gas monitoring such as mine gas monitoring e.g. methane monitoring (claimed) for mine safety production monitoring. ADVANTAGE - The core mismatched optical fiber sensor provides good output light intensity and reasonable linear relationship as well as excellent recoverability, and provides higher sensitivity and faster response speed, and overcomes many shortcomings of the D-type fiber-optic gas sensor. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing a graphene-based core mismatch type optical fiber sensor. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a graphene-based core mismatch type optical fiber methane sensor. (Drawing includes non-English language text) Tin oxide layer (1) Line (A,B) Standard multimode fibre (MM) Standard single-mode optical fibre (SM)