Thin film polarisers for high power densities

Laser Components has introduced a range of four types of thin film polarisers based on glass substrates, which it says are ideal for use in high power density applications.

The standard polarisers are based on a Brewster angle of 56°. The polarising coating used is only required on the front face in order to achieve a good extinction ratio; a rear side anti-reflection coating is not required.

Adjustment-free thin film polarisers have the added benefit of being able to be used at any angle from 53° to 59° due to a broadband monitoring technique used in the coating process. Polarisers are available optimised for wavelengths in the 450-1,064nm range. The polarisers are manufactured using the company's ion-assisted deposition (IAD) technique, resulting in polarisers with a high reflection of s-polarised light and a high transmission of p-polarised light.

For applications requiring an alternative angles of incidence, the 45° thin film polariser is a good and often inexpensive system to set up, as the s-polarisation is deflected by 90°, thus a standard mount for bending mirrors can be used. The rear surface is anti-reflection coated for the p-polarisation.

For broadband systems, such as Ti:sapphire fs lasers, the company also offers broadband plate polarisers. These are used at an angle of 72° and can be used in both directions. Laser Components notes, however, that the p-polarisation is slightly offset and the s-polarisation is deflected at an angle of 144°.

The substrates for all of these thin film polarisers can be chosen from a wide selection of standard windows, and customised solutions are also available.