Self-mode-locked pulsed monomode laser

We predict the existence of a new pulsed-laser operation regime, when the phases and polarizations of the two coupled cold-cavity eigenstates of a monomode solid-state laser are taken into account in the derivation of the Maxwell-Bloch equations. This monomode pulsed regime is experimentally observed, without any normal mode locking or Q switching occurring inside the cavity. We obtain close agreement between experiments and theory, even in the simple case of a Nd:YAG microchip laser, for which sech² pulses at nearly megahertz repetition rates are readily observed.