What is the difference between polarizing and non-polarizing beamsplitters?

The polarization of light is changed when it is incident on a beamsplitter oriented at 45°. For randomly polarized input light, the S-polarization state is reflected more than the average amount of reflection and the P-polarization state is reflected less than the average. Plate beamsplitters are very sensitive to polarized light, the transmission of the S- and P-polarization states can each vary typically as much as 20% from the average at 550nm for a visible spectrum coating. Our dichroic cube beamsplitters are also extremely sensitive to polarization. The S- and P-polarization states can have a difference as large as 70%, while differing from the average transmission by approximately 20-30%. Beamsplitters should be selected carefully prior to integration into polarization sensitive applications. We do offer polarized cube beamsplitters that offer 92% reflection for S-polarization at 632.8nm.

Non-polarizing beamsplitters are primarily designed for polarization sensitive applications requiring 50% reflection and 50% transmission, when the polarizing effects need to be kept to an absolute minimum. They are typically optimized for a specific laser wavelength with the s- and p-polarization states of the transmitted beam differing by less than 5%. In essence, the coating does not change the polarization characteristics of the incident beam.