| 摘要 |
A means for intracavity sum frequency generation is described in which a laser operates simultaneously, cw, at two wavelengths where the net gain at one wavelength is substantially lower than that at the other. The optical alignment of the resonator provides a region where both fundamental wavelengths are overlapped, and another region where both feedback paths are spatially distinct. An active feedback mirror is located in the path of the lower net gain laser transition to provide optical amplification at that wavelength. The laser resonator further contains a sum frequency generating crystal for intracavity sum frequency generation of the two fundamental wavelengths. The sum frequency generating crystal is placed near a laser resonator cavity mode waist in the region where both wavelengths are spatially superimposed, producing the sum frequency of the two wavelengths. An intracavity polarization rotator provides the appropriate orientation of the polarization of the two fundamental wavelengths in the laser gain element as well as in the non-linear sum frequency generating crystal. Line narrowing of the individual two fundamental wavelengths produces a line narrowed sum frequency generated output. Sum frequency generation at 459 nm is demonstrated in a non-critically phase matched Type II KTP crystal by operating a Ti:sapphire laser simultaneously at 808 nm and 1.064 mu .
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