External feedback optimization by means of polarization control in fiber Bragg grating stabilized 980-nm pump lasers

Effects of polarization change in the feedback provided by fiber Bragg gratings that stabilize 980-nm pump lasers are investigated. The effective feedback in the proper transverse-electric polarization is calculated from an easily measured parameter, describing the polarization at the fiber grating. This provides a useful experimental tool to investigate the effect of feedback loss due to polarization change that can occur in nonpolarization maintaining fibers. On the basis of our calculations, we give guidelines for optimum fiber layout to minimize polarization change.