Multi-color laser generation in periodically poled KTP crystal with single period

Frequency conversion based on three-wave mixing is a critical nonlinear optic application, extending the frequency range of existing lasers and realizing frequency-transduced detectors in wavelength that lacks an effective detector. Phase matching vital for conversion. The advantages quasi-phase (QPM) over birefringent phase are lack walk-off effect, maximum coefficient, entire transparency window. Herein, using different types orders QPM, four kinds doubling processes realized periodically poled potassium titanyl phosphate (KTP) crystal with single period, three experimentally verified. We also show feasible way to construct RGB color generator two QPM processes. This study significantly expands wavelengths, providing method multi-color laser generation KTP crystals.