Brewster Windows without Reflection losses of P-Polarization

Brewster Windows are uncoated substrates that can be used in series as polarizers, or to clean up a partially polarized beam. When positioned at Brewster’s Angle, the P-polarized component of the light enters and exits the window without reflection losses, while the S-polarized component is partially reflected. The 20-10 scratch-dig surface quality and λ/10 transmitted wavefront error of our Brewster windows make them an ideal choice for laser cavities.

Brewster windows are typically used as polarizers within laser cavities. When positioned at Brewster’s angle (55° 32′ at 633 nm), the P-polarized portion of the light will pass through the window with no losses, while a fraction of the S-polarized portion will be reflected off the Brewster window. When used in a laser cavity, the Brewster window essentially acts as a polarizer.
Brewster’s angle is given by
tan(θ_B) = n_t/n_i
θ_B is Brewster’s angle
n_i is the index of refraction of the incident medium, which is 1.0003 for air
n_t is the index of refraction of the transmitting medium, which is 1.45701 for fused silica at 633 nm

Paralight Optics offers Brewster windows are fabricated from N-BK7 (Grade A) or UV fused silica, which exhibits virtually no laser-induced fluorescence (as measured at 193 nm), making it an ideal choice for applications from the UV to the near IR. Please see the following Graph showing reflectance for both S- and P-polarization through UV fused silica at 633 nm for your references.