RF excited CO2 slab waveguide lasers are now developed as compact, highly efficient,
cost-effective high power laser sources, suitable for a large number of uses. However a
major problem remains in that the output power, wavelength and beam shape are
unstable in time, leading to restrictions in their use in high precision and wavelength
dependent work.
A new method of wavelength control has been explored, using 2-D periodic patterns
machined directly onto the waveguide surface of one of these lasers. These grating
structures have been produced using a laser micro-machining technique which has been
developed to allow for accurate and repeatable feature periodicity, along with fast
prototyping. Several geometries of gratings, both one and two dimensional, have been
machined from a number of materials compatible with IR hollow waveguide use, with
feature spacings ranging from 80-150 um.
Sensitive techniques developed to measure the wavelength dependent transmission of
these waveguides out with a laser cavity, have shown a 2-3% loss selectivity using
50mm long patterns.
The inclusion of the two dimensional grating in the unstable resonator of an industrial
slab laser device is shown to stabilise the output wavelength to the 10.59 um transition
and maintain a constant spatial mode
