Thermodynamic processes in an RF pulsed excited CO 2 slab-waveguide laser

Abstract

A pulsed excitation of the laser plasma in gas lasers creates an acoustic wave in the laser reservoir. It changes thermodynamic parameters of the laser plasma in the laser cavity like pressure, and temperature, as well, and consequently it changes the density of the laser plasma, or, in other words, the refractive index of the laser medium. Tuning laser frequency during the pulse developing is observed as a result. The measurements of the pressure, temperature, and refractive index changes in an RF pulsed excited CO 2 slab-waveguide laser are purposes of the work. The pressure changes are measured with calibrated microphones situated close to the laser plasma. The temperature changes are calculated via measured refractive index characteristics, and simple formulas linking the refractive index with the gas density. The picture of the acoustic wave propagation in the laser cavity is presented. The obtained results give the picture of the laser plasma behavior during the pulsed excitation. It leads to a single frequency pulsed laser operation design.

Spectral and thermodynamic effects in pulsed RF excited CO 2 slab-waveguide laser

“…As known, a line hoppings effect is responsible for the specific perturbations (see the upper trace in Fig. 4) visible along the pulse shape [12]. It is the evidence, that the laser is tuned ______________________________________ during the pulse developing.…”

“…A He-Ne laser is used as a source. In practice, a formula (11) leads to the relation between changes of the refractive index An and a number of fringes as follow: (12) L where: L -length of the optical resonator (380 mm for this experiment), 2-wavelength (0.63 jim for He-Ne laser).…”

“…Assuming a homogeneous exciting of the laser slab the space dependence can be neglected, and equation (9) can be rewritten into: o(x, y) = J[n(x, y, z) -n]dz = A . AS(x, y) (11) where n and n(x,y,z) [-] are refractive indices in ambient medium and in the place x,y,z, A [m] is a wave length of light and zlS(x,y) [-1 is a change in interference order in the plane x,y caused by a subject measured.…”