Brewster's Angle in lasers

In summary, Fresnel losses can be reduced by changing the angle of incidence to Brewster's angle, which minimizes reflective loss for p-polarized light. However, laser light and flashlamps/flash tubes can come in any polarization direction and can be decomposed into P and S components at the interface. At Brewster's angle, the P component is transmitted while the S component is reflected. This has been used in the design of HeNe lasers to achieve a highly p-polarized output.
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Homework Statement


Fresnel losses occur between two different media that have different refractive indices. To reduce these losses we can change the angle of incidence to brewster's angle. At this angle, the amount of reflective loss is minimized for p-polarized light.

Do we assume that laser light is p-polarised to begin with? Is the flashlamp / flashtube p-polarised? After population inversion and electron's giving off photons, they do so in a p-polarised way?
 
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The light can come in any polarization direction. Since E field is a vector, it can be decomposed into components. In the case of refraction and reflection at the interface, one typically consider the so-called P and S polarization direction. These directions are mutually perpendicular. The incoming light can then be decomposed into components along these two directions. When the light is incident at the Brewster angle, however, there is no reflection for the P component, i.e. all portion in the P direction gets transmitted. But the other component, the S component, still gets reflected.
 
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I think I have seen the Brewster angle used in design of a HeNe laser where left and right outside face of the discharge tube are at the Brewster angle and the mirrors that complete the cavity are outside of the discharge tube. The resulting laser will then be very much p-polarized because the cavity Q wouldn't be high enough to have lasing properties for the s-polarization because of the reflective losses across the glass discharge faces. The p-polarization meanwhile has nearly 100% transmission across these faces.
 

What is Brewster's Angle in lasers?

Brewster's Angle in lasers is the angle at which a polarized light wave is perfectly reflected off of a surface. It was discovered by Sir David Brewster in the 19th century and is an important concept in laser technology.

How is Brewster's Angle calculated?

Brewster's Angle can be calculated using the formula tan θ = n2/n1, where θ is the angle of incidence, n2 is the refractive index of the medium the light is entering, and n1 is the refractive index of the medium the light is coming from.

Why is Brewster's Angle important in laser technology?

Brewster's Angle is important in laser technology because it allows for the production of polarized light, which is crucial for many laser applications such as laser cutting and telecommunications. It also helps to minimize reflection losses and improve the efficiency of lasers.

Can Brewster's Angle be applied to all types of lasers?

Yes, Brewster's Angle can be applied to all types of lasers, including gas, solid-state, and semiconductor lasers. However, the exact angle may vary depending on the specific properties of the laser medium and the material it is interacting with.

What are some real-world applications of Brewster's Angle in lasers?

Brewster's Angle is used in a variety of real-world applications, including laser surgery, laser spectroscopy, and laser printing. It is also important in the production of polarizing filters for cameras and other optical devices.

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