Abstract: A single frequency filter for a laser, comprising a polarizer that defines a direction of polarization and one or more birefringent elements situated within the cavity with their dielectric axes offset from the direction of polarization. The ends of the birefringent elements have a finite reflectance, and may be coated for reflectance or left uncoated. In some embodiments the filter is situated in a laser cavity with a broadband gain medium, in other embodiments, the filter is situated in an external cavity. To provide tunability, a wavelength control system is coupled to the birefringent element. An embodiment is described in which the filter comprises two birefringent elements of unequal optical length along the optical axis, which advantageously reduces the voltage required to tune the frequency. To provide tunability, the first and second birefringent elements are both coupled to a wavelength control system that simultaneously controls both elements.

Abstract: A single frequency filter for a laser, comprising a polarizer that defines a direction of polarization and one or more birefringent elements situated within the cavity with their dielectric axes offset from the direction of polarization. The ends of the birefringent elements have a finite reflectance, and may be coated for reflectance or left uncoated. In some embodiments the filter is situated in a laser cavity with a broadband gain medium, in other embodiments, the filter is situated in an external cavity. To provide tunability, a wavelength control system is coupled to the birefringent element. An embodiment is described in which the filter comprises two birefringent elements of unequal optical length along the optical axis, which advantageously reduces the voltage required to tune the frequency. To provide tunability, the first and second birefringent elements are both coupled to a wavelength control system that simultaneously controls both elements.

Abstract: A laser in which the laser emission is autocoupled into an optical fiber. The laser cavity is insensitive to misalignment; i.e. it will oscillate if the optical fiber is positioned within an allowed volume determined by a degenerate resonator configuration. In one embodiment, a solid state laser includes two ball lenses arranged on opposing sides of the gain medium. The degenerate resonator configuration is defined on one end by a reflectively-coated outer surface of the ball lens. The other end is approximately defined by an allowed volume on the outer surface of the second ball lens. To provide a laser cavity the reflective end of the optical fiber is situated within the allowed volume. The laser may be end-pumped using a fiber-coupled laser diode, and the ball lens is used to focus the pump beam into the gain medium. The reflective end may be provided by a Bragg grating.

Abstract: A composite cavity continuous wave (cw) microlaser that lases at two fundamental wavelengths, denoted by .lambda..sub.1 and .lambda..sub.2, which are frequency-mixed in a suitable nonlinear crystal oriented within an optically resonant cavity for phase-matched frequency mixing to generate radiation at a third wavelength. The optically resonant cavity is defined by a first reflective surface and a second reflective surface, both of which are substantially reflective at a first and a second wavelength. A highly absorbing solid-state gain material, preferably Nd:YVO.sub.4, which has a first gain transition at the first wavelength and a second gain transition at the second wavelength different from the first wavelength is disposed within the optically resonant cavity. The highly absorbing solid-state gain material is closely coupled to the first reflective surface to promote single mode operation of both fundamental lasing frequencies.

Abstract: A dual wavelength continuous wave (cw) solid state microlaser device that provides simultaneous laser action at a first and a second wavelength. The laser comprises a solid state gain material including a rare earth element having a first gain transition at the first wavelength and a second gain transition at the second wavelength. The gain material defines a block having a first face and a second, opposite face. A first reflective surface that is substantially reflective at both the first and second wavelengths is closely coupled to the first face. An output coupler provides a second reflective surface that is partially reflective at both the first and the second wavelengths, which is oriented with respect to the first reflective face to define an optical cavity through the first and second faces of the solid state gain material. An optical pump source is provided to end pump the solid state gain material with continuous pump radiation at a pump wavelength that is highly absorptive by the gain material.