The Generation of Powerful Rainbow-Color Laser Emission by Four-Wave Raman Mixing for Display and Illumination.

Abstract

In order to generate a multifrequency laser emission, consisting of the entire rainbow of colors, two approaches are demonstrated and compared for commercial application, such as displays and illumination. One approach uses a second harmonic emission of a Nd:YAG laser emitting at 532 nm as the main pump beam and a dye laser, which is pumped by a part of the Nd:YAG laser, as a seed beam. These beams are coaxially aligned and are focused into two Raman cells filled with hydrogen to generate multifrequency laser emission based on four-wave Raman mixing. The other approach is more straightforward and involves an elliptically polarized second harmonic emission of a Nd:YAG laser, instead of a two-color laser beam, which is simply focused into the Raman cells. The entire rainbow colors (more than 20 emission lines from 400 nm to 800 nm) are generated in both the approaches. More efficient generation of the regular (quasi-equally spaced) spectral lines with a flatter intensity distribution is achieved by the former approach. The output power obtained is 600 mW (60 mJ×10 Hz).