Simultaneously tunable two-wavelength dye laser using two dielectric multilayer filters

A nitrogen-laser-pumped tunable dye laser using a single dielectric multilayer filter as the tuning element has been reported by Nomura et al. (1982). A description is given here of a simultaneous tunable two-wavelength dye laser pumped by a nitrogen laser using a second dielectric multilayer filter to extend the first. The first dielectric multilayer filter (1-nm FWHM at 467.9 nm; 50 percent peak transmittance), which is inserted between two mirrors having reflectivities of 70 percent and 100 percent, tunes at one wavelength. The light is reflected by the layer over nearly the whole of the wavelength region, except the transmitted wavelength, which is tuned by the two mirrors. Another wavelength is selected by the second dielectric multilayer filter (1-nm FWHM at 468.9 nm; 50 percent peak transmittance), which is inserted between the first filter and a third mirror, whose reflectivity is 100 percent. It is pointed out that this laser can be used in a differential absorption lidar system because of the perfect collinearity of the tuning spectra.