Circular laser

A laser structure for sustaining preferred cavity modes with an optical radiation of wavelength, λ0, comprising:

• a.) cavity structural means, the structural means providing optical surfaces for forming an optical cavity;
• b.) a reflective coating deposited on the optical surfaces, the coating providing an optical cavity, the optical cavity having a cavity interior with an interior index of refraction, the coating including at least one hundred-eighty thin film dielectric layers, the layers having alternating refractive indices, the alternating refractive indices differing by less than 0.1, the coating providing greatest reflectance to the radiation at a preferred angle-of-incidence, so that the coating is substantially reflecting to the radiation only at approximately the angle-of-incidence, such that the radiation only provides the modes when the radiation is propagating at approximately the preferred angle-of-incidence;
• and,
• c.) a gain medium in the cavity interior, the medium disposed for emitting the radiation into the preferred modes.

A gas laser cavity structure for providing lasing cavity modes of a preferred wavelength, comprising:

• a.) a cavity structure providing a spherical surface of revolution;
• b.) an optical coupling structure located centrally within the cavity;
• the coupling structure providing means for coupling energy out of the cavity;
• c.) a multilayer dielectric reflector deposited on the surface, the reflector defining an optical cavity, the reflector having an angle-dependence, so that the lasing cavity modes are substantially limited to radiation that intersects the coupling structure;
• and,
• d.) a gain medium within the cavity, the medium disposed for emitting optical radiation into the lasing modes when the medium is pumped by pumping means.