Pulsed and cw operation of helium-water vapor laser at 28 microm

The operating characteristics of a water vapor-helium laser working at 28 microm are presented. Comparison is made of power output in continuous and pulsed operation for various gas mixtures and discharge currents for the same laser cavity.     

In situ and air index measurements: influence of the deposition parameters on the shift of TiO2/SiO2 Fabry-Perot filters

We measure the refractive index of thin films of TiO2 and SiO2 for given deposition parameters. Two complementary methods are used. The first is a postdeposition technique which uses the measurements of reflectance and transmittance in air. The second, in contrast, makes use of in situ measurements (under vacuum and during the actual deposition of the layer). The differences between the values deduced from the two methods can be explained by the amount of atmospheric moisture adsorbed by films. One tries to minimize these shifts for the two materials by choosing deposition parameters. The difficulties come from the absorption losses which must be as small as possible. We use the measured refractive indices of individual layers to give good numerical prediction of the wavelength shift (observed during the admittance of air after deposition in the vacuum chamber) of the transmittance peak of multidielectric Fabry-Perot filters.