A polarization rotator, comprising: a) a first transceiving waveguide, comprising a first end and a second end; b) a polarization rotation region waveguide, comprising a first waveguide and a second waveguide, wherein the first waveguide is located above the second waveguide, the first waveguide is connected to the second end of the first transceiving waveguide, the first waveguide is a non-linear profile waveguide, and the second waveguide is a non-linear profile waveguide; c) a mode conversion region waveguide, comprising a third waveguide and a fourth waveguide, wherein the third waveguide is connected to the second waveguide, the fourth waveguide is on a same horizontal plane as the third waveguide and the second waveguide, the third waveguide is a non-linear profile waveguide, and the fourth waveguide is a non-linear profile waveguide, wherein d) the first to fourth non-linear profile waveguides (1021, 1022; 1031, 1032) in b) an c) mean a waveguide with an exterior shape profile which, along a propagation direction, varies non-linearly, wherein e) the first transceiving waveguide does not overlap the second waveguide; and f) a second transceiving waveguide, comprising a third end and a fourth end, wherein the third end of the second transceiving waveguide is connected to the fourth waveguide, a distance between the fourth end and the second end of the first transceiving waveguide is greater than a distance between the third end and the second end of the first transceiving waveguide; wherein g) the first transceiving waveguide is configured to receive an L-order mode transverse magnetic wave, TM mode optical signal, the polarization rotation region waveguide is configured to convert the L-order mode TM mode optical signal into an N-order mode transverse electric wave, TE mode optical signal, the mode conversion region waveguide is configured to convert the N-order mode TE mode optical signal into an M-order mode TE mode optical signal, and the second transceiving waveguide is configured to output the converted-to M-order mode TE mode optical signal, wherein N is not equal to M; or h) the second transceiving waveguide is configured to receive an M-order mode TE mode optical signal, the mode conversion region waveguide is configured to convert the M-order mode TE mode optical signal into an N-order mode TE mode optical signal, the polarization rotation region waveguide is configured to convert the N-order mode TE mode optical signal into an L-order mode TM mode optical signal, and the first transceiving waveguide is configured to output the converted-to L-order mode TM mode optical signal, wherein N is not equal to M. a) a first transceiving waveguide, comprising a first end and a second end; b) a polarization rotation region waveguide, comprising a first waveguide and a second waveguide, wherein the first waveguide is located above the second waveguide, the first waveguide is connected to the second end of the first transceiving waveguide, the first waveguide is a non-linear profile waveguide, and the second waveguide is a non-linear profile waveguide; c) a mode conversion region waveguide, comprising a third waveguide and a fourth waveguide, wherein the third waveguide is connected to the second waveguide, the fourth waveguide is on a same horizontal plane as the third waveguide and the second waveguide, the third waveguide is a non-linear profile waveguide, and the fourth waveguide is a non-linear profile waveguide, wherein d) the first to fourth non-linear profile waveguides (1021, 1022; 1031, 1032) in b) an c) mean a waveguide with an exterior shape profile which, along a propagation direction, varies non-linearly, wherein e) the first transceiving waveguide does not overlap the second waveguide; and f) a second transceiving waveguide, comprising a third end and a fourth end, wherein the third end of the second transceiving waveguide is connected to the fourth waveguide, a distance between the fourth end and the second end of the first transceiving waveguide is greater than a distance between the third end and the second end of the first transceiving waveguide; wherein g) the first transceiving waveguide is configured to receive an L-order mode transverse magnetic wave, TM mode optical signal, the polarization rotation region waveguide is configured to convert the L-order mode TM mode optical signal into an N-order mode transverse electric wave, TE mode optical signal, the mode conversion region waveguide is configured to convert the N-order mode TE mode optical signal into an M-order mode TE mode optical signal, and the second transceiving waveguide is configured to output the converted-to M-order mode TE mode optical signal, wherein N is not equal to M; or h) the second transceiving waveguide is configured to receive an M-order mode TE mode optical signal, the mode conversion region waveguide is configured to convert the M-order mode TE mode optical signal into an N-order mode TE mode optical signal, the polarization rotation region waveguide is configured to convert the N-order mode TE mode optical signal into an L-order mode TM mode optical signal, and the first transceiving waveguide is configured to output the converted-to L-order mode TM mode optical signal, wherein N is not equal to M.