| 摘要 |
A laser includes a pumping light source for producing a pumping beam and a laser resonator having an input mirror optically coupled to the pumping light source for receiving the pumping beam. The laser resonator also includes an output mirror, a lasant material, and a nonlinear optical material. The nonlinear optical material is placed inside the laser cavity and configured as a half-wave plate or a multiple of a half-wave plate at a first given fundamental lasing wavelength. The lasant material is placed against or near the input mirror of the laser resonator and oscillates in response to the pumping beam so as to generate a fundamental wave including (i) two substantially orthogonal linearly polarized modes at wavelengths at and/or about the first given wavelength, (ii) an additional mode at and/or about a second given wavelength that is relatively close to but different from the first given wavelength. The nonlinear material produces multiple second harmonic linearly polarized mode as its output that are at wavelengths at and/or about half the fundamental wavelengths. The laser resonator further includes a filter arrangement for allowing the additional mode at about the second given wavelength to leak out of the laser resonator. The oscillation of the additional mode at the second given wavelength is suppressed because of the filter arrangement. This results in a laser which produces only two substantially orthogonal linearly polarized fundamental modes at the first given wavelength. This laser has minimized sum frequency generation and its second harmonic output is thus free from "green noise".
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