A micro-ring resonator, comprising: a first straight waveguide; a second waveguide and a third waveguide, wherein the second waveguide and the third waveguide form a closed annular waveguide or form an unclosed annular waveguide, and the annular waveguide is coupled to the first straight waveguide; a fourth waveguide, wherein the fourth waveguide is arc-shaped and coupled to the third waveguide; and a first polarization splitter and a second polarization splitter, wherein the first polarization splitter is connected to one end of the fourth waveguide, and the second polarization splitter is connected to another end of the fourth waveguide, wherein in a first coupling area, wherein the first coupling area is a coupling area in which the annular waveguide is coupled to the first straight waveguide, input light containing TM mode polarized light and TE mode polarized light enters the annular waveguide; in the first coupling area, the second waveguide, and a second coupling area, TE mode polarized light and TM mode polarized light exist simultaneously; and when the TE mode polarized light passes through the first polarization splitter a path of the TE mode polarized light is through the third waveguide; and when the TM mode polarized light passes through the first polarization splitter, the polarization state is rotated to TE, and a path of the rotated TM mode polarized light is through the fourth waveguide; and after the TE and rotated TM mode polarized light are transmitted through the fourth and the third waveguide (Arm1, Arm2) separately, the TE and rotated TM mode polarized light enter the second polarization splitter; when the TE mode polarized light passes through the second polarization splitter, the polarization state of the TE mode polarized light keeps unchanged, and the TE mode polarized light enters the first coupling area; when the rotated TM mode polarized light enters the second polarization beam splitter it is rotated from TE back to TM, and becomes TM mode polarized light again and enters the first coupling area; and wherein an optical path difference generated by a length difference of the fourth waveguide and the third waveguide (Arm 2) is used to compensate for an optical path difference that exists due to different TE and TM polarizations in the second waveguide so as to ensure that optical paths of the TE mode polarized light and the TM mode polarized light are consistent. a first straight waveguide; a second waveguide and a third waveguide, wherein the second waveguide and the third waveguide form a closed annular waveguide or form an unclosed annular waveguide, and the annular waveguide is coupled to the first straight waveguide; a fourth waveguide, wherein the fourth waveguide is arc-shaped and coupled to the third waveguide; and a first polarization splitter and a second polarization splitter, wherein the first polarization splitter is connected to one end of the fourth waveguide, and the second polarization splitter is connected to another end of the fourth waveguide, wherein in a first coupling area, wherein the first coupling area is a coupling area in which the annular waveguide is coupled to the first straight waveguide, input light containing TM mode polarized light and TE mode polarized light enters the annular waveguide; in the first coupling area, the second waveguide, and a second coupling area, TE mode polarized light and TM mode polarized light exist simultaneously; and when the TE mode polarized light passes through the first polarization splitter a path of the TE mode polarized light is through the third waveguide; and when the TM mode polarized light passes through the first polarization splitter, the polarization state is rotated to TE, and a path of the rotated TM mode polarized light is through the fourth waveguide; and after the TE and rotated TM mode polarized light are transmitted through the fourth and the third waveguide (Arm1, Arm2) separately, the TE and rotated TM mode polarized light enter the second polarization splitter; when the TE mode polarized light passes through the second polarization splitter, the polarization state of the TE mode polarized light keeps unchanged, and the TE mode polarized light enters the first coupling area; when the rotated TM mode polarized light enters the second polarization beam splitter it is rotated from TE back to TM, and becomes TM mode polarized light again and enters the first coupling area; and wherein an optical path difference generated by a length difference of the fourth waveguide and the third waveguide (Arm 2) is used to compensate for an optical path difference that exists due to different TE and TM polarizations in the second waveguide so as to ensure that optical paths of the TE mode polarized light and the TM mode polarized light are consistent.