Exploiting birefringent thermal lensing effect to manipulate polarization states of an Nd:YVO4 self-mode-locked laser

Abstract

An Nd:YVO4 laser with a convex-plano cavity is systematically studied to demonstrate the manipulation of output polarization state by using the birefringent thermal lensing effect of the gain crystal. Based on the theoretical analysis of the cavity stability under the influence of thermal lens, the polarization state of output emission is experimentally confirmed that can be controlled to switch from pure pi- to pure sigma-polarization by simply varying the pump focus position from the tight-focusing to defocusing conditions. More importantly, it is found that there exists an adequate pump focus position within the switching region to lead the pi- and sigma-polarization to have balanced gain for achieving a stable self-mode-locked laser with orthogonally polarized components. Under the orthogonally polarized mode-locked operation, the pulse repetition rates are found to be 2.23 and 2.33 GHz for the pi- and sigma-polarization with pulse duration to be 16.1 and 15.1 ps, respectively. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement