The invention discloses a preparation method of an LPFG torsion sensor based on a rotary single-mode
optical fiber and the sensor. The method comprises the following steps: heating a single-mode
optical fiber through
oxyhydrogen flame, and driving two ends of the single-mode
optical fiber to rotate
clockwise and anticlockwise respectively by a rotary clamp; obtaining a rotary single-mode optical
fiber after a preset time is reached;
etching a first group of groove modulation areas on the rotating single-mode optical
fiber; controlling the two ends of the rotating single-mode
fiber to rotate by a preset angle at the same time, and
etching a second group of groove modulation areas on the rotating single-mode fiber; and controlling the two ends of the rotary single-mode fiber to reversely rotate so as to restore to an initial state, thereby obtaining the LPFG torsion sensor. The rotary single-mode optical fiber is prepared through
oxyhydrogen flame heating and rotation, and a large amount of twisting force is cured; and meanwhile, the rotary single-mode fiber is rotated and the groove is etched, so that the introduced
linear birefringence and circular
birefringence are increased, the elliptical
birefringence is further increased, the drift distance of the resonant
wavelength during torsion is increased, and the torsion sensitivity of the LPFG torsion sensor is improved.