Abstract

We have recently performed some experiments with a standing-wave CW dye laser with a BaTiO₃ crystal intracavity element. A holographic grating formed within the crystal by the counterpropagating waves in the laser cavity generates positive feedback that is strongly frequency selective. The laser has a narrow linewidth with unusual mode patterns that depend upon the position of the crystal along the cavity axis. The output frequency is unstable for most positions of the crystal but is exceptionally stable for a few regions. With the crystal at one of these locations, it is possible to scan the output frequency at high resolution over a range of several hundred wavenumbers without mode jumps. The frequency stability and scanning is interpreted in terms of static and dynamic phase shifts between the light that produces the holographic grating in the BaTiO₃ crystal and the light reflected by the grating. The mode selection is due to a combination of mode competition in the gain medium and the variation of grating contrast with the different patterns of oscillating modes.

© 1987 Optical Society of America