Laser Line Optics

Author: the photonics expert Dr. Rüdiger Paschotta

Various kinds of optical components have been developed for use with specific laser lines. This has led to the term laser line optics, or more specifically to terms like laser line mirrors, laser line polarizers, etc.

Frequently, the restriction to certain operation wavelengths (more precisely, certain limited wavelength regions) arises from limitations of dielectric coatings, which intrinsically have wavelength-dependent reflection properties. For example, dielectric laser mirrors can achieve a high reflectivity (or some other defined reflectivity value, e.g. for beam splitters or output couplers) only in quite limited wavelength regions. The same holds for anti-reflection coatings and thin-film polarizers.

Although it is possible to make broadband coatings, which allow for substantially wider ranges of operation wavelength, those tend to be more complex and therefore more expensive. Further, narrowband coatings can exhibit a substantially better performance. Therefore, such coatings for narrow specific wavelength regions are often used when operation is anyway limited to such a region.

Certain wavelength restrictions also intrinsically apply to components like waveplates and birefringent tuners, further to various kinds of diffractive optics. Besides, there are certain optical filters, e.g. for blocking certain laser lines as required for applications like Raman spectroscopy.

Laser line optics are mostly available for a limited set of common laser wavelengths, for example:

• 1064 nm from Nd:YAG or Nd:YVO₄ lasers
• 532 nm, 355 nm, 266 nm (harmonics of those, obtained by nonlinear frequency conversion)
• 514 nm (argon ion lasers)
• 633 nm (helium–neon lasers)

They include components like laser mirrors, polarizers, waveplates, beam collimators, beam shapers, optical filters and optical windows.

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Encyclopedia articles:

• laser lines