Source: 3photon: crystals
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Understanding Variable Reflectivity Mirrors

Overview

Variable reflectivity mirrors are mirrors that exhibit a spatial variation in their reflectance. This variation can be achieved through different mirror designs and fabrication techniques.

Operation Principles

Variable reflectivity mirrors are typically designed with radially symmetric reflectance profiles. This means that the reflectance varies based on the distance from the center of the mirror. Various mirror profiles can be used, such as Gaussian, supergaussian, parabolic, or Bessel function profiles. The reflectance can also depend on linear coordinates.

Fabrication

One common method of fabricating variable reflectivity mirrors is by depositing a highly reflecting layer with variable thickness on a mirror substrate. This layer can be a metallic coating or a high-index dielectric material. Spatial dependence in reflectance can be introduced by using masks during deposition or by modifying reflection properties post-production using laser radiation.

Applications

Variable reflectivity mirrors find applications in lasers with unstable resonators as output couplers to control beam diameter. They are also used in variable attenuators where reflectance variations allow for beam attenuation adjustments. These mirrors enable the construction of lasers with large mode areas and high beam quality.

Conclusion

Variable reflectivity mirrors play a crucial role in laser systems and optical devices where controlling reflectance profiles is essential for beam quality and performance optimization.

Source: 3photon: crystals
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