Mode-volume enhancement in an apertured laser

In a laser TEM(00)-mode selection by the use of a hard intracavity aperture gives rise to losses that are experimentally observable and to an increase in the fundamental-mode volume that is more difficult to observe. We use the parasitic resonances that are characteristic of multicavity lasers to demonstrate this volume enhancement in a He-Ne laser operating at 3.39 µm. The increase in mode volume in the apertured laser can increase the output power by a factor of 3 with respect to that of the nonapertured laser.