QCLs can be stored at ambient temperature (10..30C) in normal
atmosphere. Humidity should not excess about 80%, and condensation is
to be avoided. When operated, only dry atmosphere (below 50% relative
humidity) is allowed, and if possible, it should be completely dried
(desiccant material, N2 atmosphere).
The laser should always lay flat (with its vertical axis upwards) on a flat and stable surfaces, without touching anything around its circumference. Of course, when mounted in an appropriate and stable holder, it can be operated in any orientation.