KTP倍频器件温度适应性扩展研究

Study on temperature adaptability extension of KTP frequency-doubling device

针对目前最常用的KTP倍频晶体,综合考虑其有效非线性系数和温度半宽度,采用折中设计有效扩展KTP倍频器件适用温度范围.对大适用温度范围的KTP倍频器件的设计方法进行了详细的理论分析,并设计了一种温度半宽度为-20℃到50℃的KTP倍频器件.实验结果表明该器件在15℃时达到峰值转换效率22.7%,温度半宽度为70℃.和通常情况下设计的KTP倍频器件相比,尽管倍频转换效率有所下降,但显著提高了适用温度范围.且在温度半宽度高达70℃情况下,其有效非线性系数仍大于LBO,BBO等倍频器件.该方法对于扩展倍频器件的温度适应性具有普适性.

For the most commonly used KTP frequency-doubling crystal, its temperature adaptability range should be ef- fectively extended. For this purpose, a compromise design is given by comprehensively considering both its effective nonlinear coefficient and the half-width of temperature range. The design method of KTP frequency-doubling device with a wide temperature range is analyzed in detail; furthermore, the curves of effective nonlinear coefficients, acceptance angles, and walk-off angles as a function of phase-matching angle are plotted via computer simulation. According to the results of theoretical study, a device used in the temperature range from -20 ℃ to 50 ℃ is designed and validated ex- perimentally by the KTP external cavity frequency-doubling laser. Experimental results indicate that a peak conversion efficiency of 22.7% at 15 ℃ with a 70 ℃ temperature halfwidth is achieved by using the designed device. Compared with the commonly designed KTP frequency-doubling device, the temperature adaptability range increases notably although its frequency conversion efficiency decreases a little. Additionally, the effective nonlinear coefficient is still bigger than that of the commonly used crystals such as LBO and BBO when temperature halfwidth increases to 70 ℃. The above method would have the potential for extending the temperature adaptability range of other frequency-doubling devices.