This paper describes a single transverse mode Q-switched Nd3+ glass laser working on a few longitudinal adjacent modes. The narrowing of the spectral output is obtained by use of a resonant reflector and a birefringent filter under temperature control. The number of longitudinal modes is varied from one to ten with a constant energy output of 10 mJ by means of intracavity resonators and two-step Q-switching. Observations of the quasiperiodic intensity fluctuations during the 40-nsec pulse give information about the statistical character of multimode giant pulse laser emission.
F. Sanchez and C. Lecompte, "Q-Switched Nd3+ Glass Laser of Variable Temporal Coherence," Appl. Opt. 13, 1071-1076 (1974)