Self-Q-switching of ruby lasers at 77°K

Self-Q-switching of a ruby laser rod at 77°K is reported. Detailed studies indicate that the basic mechanism involved is a saturable-absorber process achieved by shielding a particular part of the rod from the pump. An essential feature is that a non-uniform cavity photon density is required to achieve saturable-absorberQ-switching by unpumped laser atoms. Measurement of the pulse growth from noise and other pulse parameters is in reasonably good agreement with the saturable-absorber giant-pulse theory.