Abstract

On considering an argon excimer laser as an extremely intense coherent light source in the VUV region, a frequency tunability is one of the most important problems. An argon excimer laser pumped by a pulsed electron beam (700kV, 60ns) has previously been reported to have the maximum power of 3.4MW using MgF₂ and Si mirrors.[1,2] Replacing the Si mirror to a set of MgF₂ prism and SiO₂ mirror as shown in Fig.1, we have successfully tuned the wavelength between 124nm and 127.5nm without any optical damages on the mirror and prism surfaces on keeping the laser output power exceeding 1MW. Stimulated Raman scattering(SRS) is feasible for further frequency conversion. We have made SRS experiments using H and obtained intense first and second Stokes lines at 133.6nm and 141.4nm using the 126.5nm laser line (Fig.2). To extend the wavelength toward shorter regions, the anti-Stokes scatterings are available. The H₂ gas shows strong dispersion of the refractive index in this frequency region. In order to make phase matching between the laser light and the Raman light, a mixture of the H₂ gas and some negative dispersion gases in this frequency region such as xenon is required. By combining the frequency conversion using SRS effects and the tuning technique of the argon excimer laser, the laser generates an extremely intense coherent light around 126nm in the VUV region. D₂ gas has a Raman shit of 2986cm compared with 4160cm of H₂ gas, so we can say that we have now an intense coherent light source in the range between 118nm and 141nm.

© 1986 Optical Society of America