Abstract

The simplest distributed feedback dye laser (DFDL) involves using a transmission grating as an input window of the dye cell.^1,2 With a single pump beam the output frequency of this laser is determined only by the grating on the dye cell window and the index of refraction of the dye solution. Although this laser is reliable and easy to operate, smooth frequency tuning is not practical In order to tune the laser frequency we project a coarse grating into a dye cell with a high-frequency holographic grating window as shown in Fig, 1(b). The two gratings produce numerous pump beams that interfere in the dye solution creating six different gain gratings. If we block the zeroth order beam after the coarse grating, only three gain gratings are formed in the dye solution. Varying the magnification of tire coarse grating tunes two of the three lines, which correspond to the difference and the sum of the spatial frequencies of the images of the coarse and fine gratings.

© 1993 Optical Society of America