▎ 摘　　要

NOVELTY - The laser has a semiconductor laser (1), a multiplexer (2), an erbium-doped optical fiber (3), a separator (4), a coupler (5), a polarization controller (6) and a tuning device (7) are serially connected together. The tuning device is connected to other end of the multiplexer to form a closed annular cavity. The tuning device is comprised of a tapered optical fiber that is placed in a magnesium fluoride substrate on a single-layer graphene thin film and a dimethyl siloxane film to cover the cone of the tapered optical fiber. USE - Multi-wavelength adjustable harmonic Q-switched optical fiber laser for use in sensing measurement, medical diagnostics and communication fields. ADVANTAGE - The multi-wavelength adjustable harmonic Q-switched optical fiber laser has compact structure, a multi-wavelength output, a wavelength tuning, a high pulse energy, and stable working at low room temperature. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the multi-wavelength adjustable harmonic Q-switched optical fiber laser. Semiconductor laser (1) Multiplexer (2) Erbium-doped optical fiber (3) Seperator (4) Coupler (5) Polarization controller (6) Tuning device (7)