Using electromagnetical force to get stress birefringence and dual frequency laser

This paper introduces a new method for both producing and controlling the frequency difference of a dual frequency laser by using an electromagnetical force which is applied onto the window plate. In our experiments, we use a half-intracavity laser. The discharge tube's window plate with high anti-reflecting film is used as a stress birefringence element. The electromagnet applies a force along a diameter of the window plate. When the voltage of electromagnet is tuned, the force is adjusted too. So the frequency difference is produced and controlled. The frequency difference is detected by a photo-electric detector and countered by a frequency meter.