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.

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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.