Abstract
A tunable 90° rotator using a cholesteric liquid crystal cell is presented. The idea is based on a unique optical feature of cholesterics, a total reflection. In the total reflection region, linearly polarized incident light is totally reflected and the incident polarization is rotated by about 70°. In other words, 80% of the incident light intensity can be converted to the perpendicular component to the incident polarization over a relatively wide spectral range, 485 nm–670 nm. The cell of another tuning range is also easily obtained by choosing the helical pitch of cholesterics.