Thin Film Polarizers and Polarizing Beam Splitters（薄膜偏振器和偏振光束分割）.pdf

Thin Film Polarizers and Polarizing Beam Splitters Angus Macleod Thin Film Center, Inc, Tucson, AZ Contributed Original Article Introduction normal to the plane of incidence, known as s-polarization. The proper- Optical coatings are stratified media. Thus, although individual films ties of the layers appear different to each eigenmode of polarization, may be isotropic, an optical coating as a whole is anisotropic, and this and so the properties of the coating also vary. This implies a different appears in the performance at oblique incidence as a sensitivity to performance for each eigenmode, which is called polarization splitting. polarization. This sensitivity can be a problem when insensitivity is a For a high-performance polarizer or analyzer it is desirable that one requirement, but, of great benefit, when the objective is the manipula- eigenmode should be completely reflected, while the other is completely tion of polarized light. Typical components are polarizers and polariz- transmitted. This is possible under certain circumstances, leading to a ing beam splitters. Most polarizers and analyzers are based on anisotro- coating that can perform the function of a polarizer or analyzer, and, pic materials, the traditional ones being birefringent crystals. A limita- because the two modes are physically separated, a polarizing beam tion common to most of them is size. Also many of the high-perfor- splitter. mance devices are not useful as polarizing beam splitters. At first sight, There are enormous advantages in thin-film devices. Their charac- the usual thin-film calculations tend to show that polarizers and polar- teristics can be placed at virtually any wavelen