Laser optics are commonly optimised for a single wavelength. When using frequency multiplying lasers, however, laser optics must be optimised for each of the wavelengths produced. So-called triple mirrors are used for this purpose, for example in Nd:YAG laser systems that emit at the fundamental wavelength 1064 nm and have harmonics at 532 nm and 355 nm, a high degree of reflectivity at each of these wavelengths is required.
Traditionally these coatings were applied in two separate runs, for example a coating for 1064 nm and 532 nm was first applied, followed by a coating for 355 nm. Consequently, production of triple mirrors was time consuming and costly.
We have developed a new coating method, allowing for production of triple mirrors in a single coating run. Not only does this reduce production time, and thus the unit cost, but also yields a higher spectral performance than previous production techniques. This method allows for triple mirrors with custom wavelength combinations to suit any application.
