Coated laser optics are used to optimize the characteristics of the emitted laser beam.---- However, losses are produced at each glass surface - thus the number of optics should be reduced to a minimum.

LASER COMPONENTS offers laser optics that have complex coatings on both the

front and the back. From a technical standpoint, this was almost impossible
to achieve for a long time in complex coatings: The coating process on the
second side heated the first coating and often caused it to crack - the more
complex the coating the more pronounced the problem as the number of layer
rises with its complexity.

Complex coating designs are manufactured upon customer request, numerous
combinations are possible: Laser optics, coated on both sides, are often
requested for the usage in resonators or for polarizers.

For applications in resonators, it makes sense to use optics with a dichroic
coating on the front, for example a coating that is highly reflective for
1064 nm and simultaneously allows the passage of pump light. The back can be
highly or partially reflective for the same or another wavelength.

It is also possible to combine a polarization coating on one side and a
mirror coating on the other side. It would be conceivable to use a thin-film
polarizer at 45° for 1064 nm, the back side of which is also coated for
coupling in another laser wavelength.

Polarization coatings on both sides of an optic are used if the polarization
effect has to be increased and the highest extinction ratios are required
that could not be achieved otherwise with a coating applied to just one
side.