Abstract
In a LiNdP4O12 microchip laser pumped by a diode laser, atomic interference arise due to the simultaneous oscillation on two transitions forming a Λ configuration. For a microchip laser, the low-frequency coherence is an important dynamical variable. It is coupled to the low spatial frequency of the population inversion grating. This results in modal intensities which are self-pulsing while the total intensity remains nearly constant. In addition, the modal power spectra display combinations of the relaxation oscillation frequencies which are absent in the power spectrum of the total output power.