RP Photonics logo
RP Photonics
Technical consulting services on lasers, nonlinear optics, fiber optics etc.
Profit from the knowledge and experience of a top expert!
Powerful simulation and design software.
Make computer models in order to get a comprehensive understanding of your devices!
Success comes from understanding – be it in science or in industrial development.
The famous Encyclopedia of Laser Physics and Technology – available online for free!
The ideal place for finding suppliers for many photonics products.
Advertisers: Make sure to have your products displayed here!
… combined with a great Buyer's Guide!
VLib part of the

Brewster Windows

<<<  |  >>>  |  Feedback

Buyer's Guide

The ideal place to find suppliers for photonics products: high-quality information, simple and fast, respects your privacy!

22 suppliers for Brewster windows are listed.

Your are not yet listed? Get your entry!

Definition: transparent plates which are oriented at Brewster's angle

German: Brewster-Fenster

Category: general optics

How to cite the article; suggest additional literature

There are situations where an optical beam must be sent through some transparent window, whereas the optical losses occurring at this window must be very small. A typical example is a helium–neon laser with a sealed glass tube and external resonator mirrors as shown in Figure 1, where glass windows separate the laser gas mixture from ambient air. Given the small gain and the small output coupler transmission, the losses at these interfaces need to be far below 1% per pass. This is achieved by using Brewster windows, where the angle of incidence is close to Brewster's angle. In that situation, the reflectivity at the air–glass interfaces becomes very small for p-polarized light, i.e., when the polarization direction is in the plane of incidence.

helium–neon laser

Figure 1: Setup of a helium–neon laser. Although two glass windows are within the laser resonator, these induce very little optical loss for p-polarized light, as they are oriented for Brewster-angled incidence.

An uncoated glass plate at normal incidence would normally have a reflectivity of several percent on each side. With an anti-reflection coating, this could be reduced to e.g. 0.2%. Brewster windows can have at least 10 times lower losses. In addition, any residual reflection will leave the resonator, rather than lead to interference effects (as can occur for windows with normal incidence). Of course, both Brewster windows in a setup as shown above must have exactly the same orientation.

Due to the significant loss difference between p and s polarization, the polarization of laser emission is usually forced to be in the p direction. In many lasers, this is the only effect determining the polarization direction.

A potential disadvantage of Brewster windows (or other polarizing optical elements) in a laser resonator is that large depolarization loss can arise if, e.g., thermal effects within a laser crystal affect the polarization. In that case, reflected beams with significant optical power and typically poor beam quality leave the Brewster windows.

Brewster windows are also often used for optical modulators and for laser housings.

See also: Brewster plates, anti-reflection coatings, gas lasers, depolarization loss

In the RP Photonics Buyer's Guide, 22 suppliers for Brewster windows are listed.

How do you rate this article?

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you like our website, you may also want to get our newsletters!

If you like this article, share it with your friends and colleagues, e.g. via social media:


Fiber Optics Software
with Further Improved
User Interface

In RP Fiber Power V6, one can use nice custom forms, which can be
tailored to specific applications.

custom form in RP Fiber Power

Users can make such forms themselves, or get them from RP Photonics within the technical support. The latter is like buying a custom software for every purpose – but without spending a lot of money every time!

Beginners can now get started very easily, even if they need quite special calculations!

– Show all banners –

– Get your own banner! –