Ivanov Grigorii Yu, Cherpak Pavel S, Konyashkin Aleksey V, Ryabushkin Oleg A
Appl Opt. 2020 Aug 20;59(24):7330-7337. doi: 10.1364/AO.400115.
Phase-matching temperature tuning curves and longitudinal temperature distribution of periodically poled lithium niobate (PPLN) crystal were measured in the process of second-harmonic generation (SHG) of 1070 nm pump wavelength using tiny transparent piezoelectric crystals as the temperature sensors. The temperatures of the crystal sensors placed along the PPLN length were determined directly by measuring the induced frequency shifts of their piezoelectric resonances, which were excited in a noncontact manner by a probe radio-frequency electric field. Such temperature sensors do not suffer additional heating conditioned by absorption of scattered radiation and also do not have any contact wires. Due to the high factors of piezoelectric resonances, the measurement accuracy of 0.05°C was achieved for a local determination of PPLN surface temperature during SHG. The self-consistent theoretical model that describes the SHG process in the presence of induced nonuniform temperature distribution of the nonlinear-optical crystal is introduced.
利用微小透明压电晶体作为温度传感器，在1070 nm泵浦波长的二次谐波产生（SHG）过程中，测量了周期极化铌酸锂（PPLN）晶体的相位匹配温度调谐曲线和纵向温度分布。沿PPLN长度放置的晶体传感器的温度，是通过测量其压电共振的感应频率偏移直接确定的，这些共振由探测射频电场以非接触方式激发。这种温度传感器不会因散射辐射的吸收而产生额外加热，也没有任何接触线。由于压电共振的高品质因数，在SHG过程中对PPLN表面温度进行局部测定时，实现了0.05°C的测量精度。引入了描述非线性光学晶体存在感应非均匀温度分布时SHG过程的自洽理论模型。
