Transverse-mode selective laser operation by unicursal fast-scanning pumping

We demonstrate that higher order transverse-mode beams can be selectively operated by creating their suitable gain distributions in a laser gain medium. By adjusting the scanning angles and the phase difference between two resonant scanning mirrors used for the manipulation of pump beam patterns, a wide variety of gain distributions such as linear, elliptical, and circular patterns were generated. As a result, single transverse-mode operations of many higher order transverse modes of Hermite-Gaussian, Laguerre- Gaussian, and Ince-Gaussian beams were realized. The switching of these modes was readily and quickly accomplished without further mechanical alignment and any optical elements.