Nanosecond pulsed laser energy and thermal field evolution during second harmonic generation in periodically poled LiNbO3 crystals
Nanosecond pulsed laser energy and thermal field evolution during second harmonic generation in periodically poled LiNbO3 crystals
复制标题
周期性极化 LiNbO3 晶体二次谐波产生过程中的纳秒脉冲激光能量和热场演化
DOI：
10.1063/1.2138786
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
K. Kitamura
中科院分区：
文献类型：
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作者：
O. Louchev;N. Yu;S. Kurimura;K. Kitamura
周期极化LiNbO3 （PPLN）晶体中纳秒脉冲激光辐射的计算研究揭示了1.064μm基频（FH）和次谐波（SH）能量场随温度场的复杂时空演化，导致了二次谐波（SHG）的热消相和抑制。所研究的激光输入功率范围为W0=0.5 ~ 50w（脉冲能量Q0=0.01 ~ 1mj∕脉冲，重复频率50kHz）。当输入激光功率为W0>10W时，跳频和跳频能量场与非均匀温度场强烈耦合，导致明显的热失相和跳频效率损失。热的产生和温度分布也表现出非常显著的不均匀性，沿着和穿过激光束，在晶体的后部或内部最大化，取决于输入功率。然而，沿工作晶体的共形温度调谐抑制了这些不均匀性，并显着提高了在高温下的SHG效率。
Computational study of nanosecond pulse laser radiation in periodically poled LiNbO3 (PPLN) crystals reveals the complex spatio-temporal evolution of the 1.064μm fundamental harmonic (FH) and second harmonic (SH) energy fields with associated temperature fields, leading to the thermal dephasing and inhibition of second harmonic generation (SHG). The investigated range of the laser input power is W0=0.5–50W (with the pulse energy Q0=0.01–1mJ∕pulse and repetition rate of 50kHz). For input laser powers W0>10W the FH and SH energy fields are found to strongly couple with nonuniform temperature field, leading to significant thermal dephasing and SHG efficiency loss. Heat generation and temperature distributions also exhibit very significant nonuniformities along and across the laser beam, maximizing at the rear or inside the crystal, depending on the input power. However, conformal temperature tuning along the operating crystal inhibits these nonuniformities, and significantly enhances SHG efficiency under hig...