Intracavity optical parametric oscillators

摘要

According to the invention, a method and an apparatus for producing a laser beam having a preselected output frequency which has a longer wavelength than does the fundamental beam of the lasing medium is provided. In one aspect of the invention a laser resonator cavity is formed between two reflective surfaces such as mirrors. A lasing medium is located within the laser resonator cavity for generating a fundamental wavelength beam. An optical parametric oscillator cavity is also formed between one of the laser resonator cavity reflective surfaces and a third reflective surface for example a mirror. A nonlinear crystal cut for phase matching conditions for the fundamental beam wavelength and the output beam wavelength is located in optical communication with the first and the third reflective surfaces. The optical axis of the laser resonator and the optical parametric oscillator are at least partially separate and partially overlap. The fundamental wavelength beam produced by the lasing medium is directed into the optical parametric oscillator cavity and incidents on the nonlinear crystal where a portion of the fundamental wavelength beam is converted to a preselected output wavelength beam along with the idler beam having a longer wavelength than the fundamental beam. The fundamental beam and the output wavelength beams are reflected back across the nonlinear crystal to form additional output wavelength beam. The output wavelength beam is separated from the fundamental wavelength beam. The separated fundamental beam is then directed back across the lasing medium for further amplification. The separated output wavelength beam is directed across the nonlinear crystal for amplification. A portion of the output wavelength beam is directed outside the oscillator cavity as the output of the laser.