Apparatus for increasing the frequency difference and stability of

Abstract

The present invention is a laser with a high reflector mirror and an output coupler mirror defining a laser resonator having an optical axis and optical path length. A gain medium, with a first refractive index and a first Verdet constant, is positioned in the resonator. The laser also includes an apparatus to excite and cause a population inversion in the gain medium to produce an output laser beam. An optically transparent medium is positioned in the laser resonator. The optically transparent medium has a second refractive index and a second Verdet constant. The second Verdet constant is typically larger than the first Verdet constant. One or more permanent and electromagnets are positioned at least partially around the exterior of the laser resonator. The magnets apply an axial magnetic field to at least a portion of the gain medium and the optically transparent medium producing a Zeeman split in the gain medium and also producing an optical path length difference between left and right circular polarizations in the laser resonator in both the gain medium and the optically transparent medium. The output laser beam is split into left and right circularly polarized output laser beams with a finite difference frequency that can be tuned and stabilized to a predetermined value which is higher than current Zeeman split lasers. The optically transparent medium can be a solid, liquid or gas, and the laser can be, by way of illustration and without limitation, a He--Ne, ion, or semiconductor laser. In embodiments, where the gain medium is a solid or liquid, the functions of the optically transparent medium are included in the gain medium.