Polarization-Insensitive Beamsplitter Components

Raw Material Properties
Laser grade ZnSe is used in the fabrication of polarization- insensitive beamsplitters.
General
Standard 50:50 beamsplitters effect the polarization of both the reflected and transmitted beams.
ULO Optics have developed a special coating ‘recipe’ which eliminates this problem, allowing
components to be used to provide a 50:50 power split at 45° incidence angle, reflecting 50% of both ‘S’
and ‘P’ polarization. As a result, incident circularly – polarized radiation is split equally into two circularly
polarized beams.
Specifications/tolerances
Diameter : +0/-0.1mm
Thickness : ± 0.1mm
Parallelism : within 2 arc minutes
Flatness : Within λ/40 over any 25mm dia list area (@10.6μm)
Reflectivity : 50% ± 1%

[both R(s) and R(p)] Absorption : <1.5% at 10.6μm, 45° incidence (circular pol.).
Laser Damage threshold : > 200W/mm cw

Application notes
1) The coating are visually opaque, (germanium is used as one of the coating layers), so this type
of beamsplitter cannot be used to split visible pointing-beams.
2) Due to the relatively high level of absorption in the coating, incident intensity levels should not
exceed 500W/cm2 in order to avoid thermal-lensing effects.
Available products
The products listed below are generally available from stock.