PHASE RETARDER AND OPTICAL COMB FILTER THEREOF

A phase retarder (10) and an optical comb filter (100) are disclosed. The phase retarder (10) includes a polarization beam splitter (11), a first air arm, and a second air arm, where the polarization beam splitter (11) is configured to decompose a beam incident on a first side wall into a first light component propagated in a first direction and a second light component propagated in a second direction, the first direction is perpendicular to the second direction, and a polarization state of the first light component is perpendicular to a polarization state of the second light component; the first air arm is disposed on a second side wall of the polarization beam splitter (11), and is configured to receive the first light component and reflect the first light component back to the polarization beam splitter; and the second air arm is disposed on a third side wall of the polarization beam splitter (11), and is configured to receive the second light component and reflect the second light component back to the polarization beam splitter (11), so that interference light is formed after the second light component interferes with the first light component, and the interference light is emitted from a fourth side wall of the polarization beam splitter (11).