The intra-cavity phase anisotropy and the polarization flipping in HeNe laser

The effect of intra-cavity phase anisotropy on polarization flipping induced by optical feedback is experimentally and theoretically investigated. In experiments, we place a polarizer in feedback cavity to induce polarization flipping. The polarization flipping doesn't occur when the angle between polarizer axis and laser polarization approaches 45 degrees. It is found that the larger the phase anisotropy is, the more easily the polarization flipping happens. As the intra-cavity phase anisotropy is increased, polarization flipping always occurs when the angle between polarizer axis and laser polarization is changed from 0 degrees to 90 degrees. This indicates that the phase anisotropy of the laser cavity contributes to the polarization flipping. It is necessary to keep certain phase anisotropy for the lasers used for polarization control. (C) 2013 Optical Society of America