A miniature three-port optical circulator (100) that comprises a first input/output (I/O) port (102), a second I/O port (112) complementary to the first I/O port, and a second walk-off crystal (145) located between the first I/O port and the second I/O port. The first I/O port receives two parallel light beams (X, Y) laterally separated from one another in a separation direction by a separation distance. The first I/O port includes a first walk-off crystal (120A) and a split polarization rotator (122) arranged in order along the optical axis (144). The first walk-off crystal is located to receive the light beams and has a first walk-off direction perpendicular (128A) to the separation direction. The split polarization rotator is mounted adjacent the first walk-off crystal and has a positive half (136A + 143A) and a negative half (138A + 143A). The split polarization rotator is located so that the polarization components of the light beams that are deviated by the first walk-off crystal pass through one of the positive half and the negative half, and the polarization components that are not deviated by the first walk-off crystal pass through the other of the positive half and the negative half. The second walk-off crystal has a second walk-off direction (166) perpendicular to the first walk-off direction, and has a walk-off distance equal to the separation distance. IMAGE
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