ZnSe Etalons

Background

We offer the world's finest solid and air spaced etalons, with fluid jet polishing systems allowing  us to routinely provide surfaces that are better than lambda/100 peak to valley.


  • Solid etalons
  • Air spaced etalons
  • Piezo tunable etalons
  • Gire Tournois etalons


We have extensive expertise in the provision of all kinds of Fabry Perot etalons from 1mm square to 100mm in diameter.  These devices require high quality, very flat optical surfaces and extreme parallelism to achieve high performance, making them a good match for the polishing and metrology at LightMachinery.


Etalons can be made from a wide variety of materials including; Fused Silica, Silicon and even Air.  Use a simple web based etalon calculator to determine the thickness and coating reflectivity to meet your requirements.



Zinc Selenide Etalons

Zinc Selenide etalons  have a reasonably high index (~2.5 depending on wavelength) that creates a reasonably high finesse without any coatings.  They also remain transmissive over a very broad wavelength range from 600nm to 20ums!.  Thermal tuning is high but not as rapid as silicon or germanium.  Unfortunately zinc selenide is one of the few optical materials that we cannot fluid jet polish (due to the grain structure), so we cannot make the parallelism super uniform and coat them to create high finesse etalons.  But for low finesse (~1.6) etalons that work over a massive wavelength range, they are pretty handy!  


Air Spaced versus Solid Etalons

Solid etalons are simple, flat, very parallel optical components. Sometimes these etalons are used uncoated using only the 4% fresnel refection to provide the etalon effect.  etalon-pair-large.jpgUncoated etalons are often used inside laser cavities since only low finesse is required filter out unwanted laser wavelengths and uncoated etalons are very damage resistant.  But generally solid etalons are coated to increase the finesse of the etalon.  Both sides are coated with the same coating.   Solid etalons are often made from Fused Silica which is an extremely pure and homogeneous material.  Solid etalons are robust, simple devices however they are prone to two forms of temperature instability.  Both the index of the material and the physical thickness of the etalon material change with temperature.  In certain applications this temperature instability is unacceptable.  This temperature dependence can also be a useful method for tuning the transmission peak position of the since it effectively changes the thickness of the etalon.  This effect can be explored more fully in our etalon calculator.