The characteristics of intensity tuning and polarization of He–Ne laserwith optical feedback are studied. When the internal cavity length ofthe laser with birefringence optical feedback is tuned, not only does outputintensity vary with laser frequency, but also the polarizationperiodically hops between two orthogonal directions. If the phasedifference of birefringence is π/2, two polarization states alternatelyoscillate and have equal bandwidths within the longitudinal modespacing. The times of polarization flipping in the longitudinal modebandwidth is proportional to the ratio of external cavity length tointernal cavity length. The experimental results are explained, and thepotential uses are also discussed.