Phase synchronization in coupled Nd:YAG lasers

We experimentally investigate the transition to phase synchronization via phase jumps in two coupled Nd:YAG lasers according to the coupling strength. As coupling constant increases chaotic outputs of the two lasers are developed from phase jumps to phase synchronization. We observe the transition route of these lasers is governed by type-II intermittency with noise. We analyze the transition behaviors by studying the phase portraits of the chaotic outputs.