| 摘要 |
PURPOSE:To prevent reflection of polarized light by impressing a specific static magnetic field upon the inside of a laser thin tube so as to make polarizing directions of adjacent longitudinal modes linear-orthogonal to each other. CONSTITUTION:Magnets 20 are arranged around a laser tube 10 so that a static magnetic field can be impressed upon the inside of the laser thin tube 11 of the laser 10 perpendicularly to the optical axis of the thin 11. The magnitude of the static magnetic field is adjusted so that the Zeeman frequency between pi and + or -alpha transition can become equal to the longitudinal-mode interval when the magnetic field is impressed. The direction of the static magnetic field is perpendicular to the axis of the laser thin tube 11 and the angle theta between the inherent polarizing direction C1 of the laser tube 10 and the direction H of the static magnetic field is set to about 30-42 deg.. In addition, the magnetic field is almost uniform in the length direction of the thin tube 11. When the static magnetic field is impressed under such conditions, the longitudinal mode repeatedly changes from (a) to (f) through (b), (c), (d), and (e) shown in the figure and the polarizing direction of each longitudinal mode does not change. Therefore, the frequency can be stabilized by a two mode method and occurrence of inversion of polarization can be prevented. |
