Takida Yuma, Nawata Kouji, Notake Takashi, Otsuji Taiichi, Minamide Hiroaki
Opt Express. 2022 Mar 28;30(7):11217-11227. doi: 10.1364/OE.452310.
Using a nonlinear optical mixing known as a frequency up-conversion process, we demonstrate an optical cross-correlation technique for the detection and characterization of sub-nanosecond (sub-ns) terahertz (THz)-wave pulses. A monochromatic THz-wave pulse from an injection-seeded THz-wave parametric generator (is-TPG) was mixed with a near-infrared (NIR) pump pulse to generate a NIR idler pulse in a trapezoidal-prism-shaped MgO-doped lithium niobate crystal under the noncollinear phase-matching condition. By measuring pump-energy and crystal-length dependencies, we show that the frequency up-conversion of sub-ns THz-wave pulses with and without subsequent parametric amplification can be used for sensitive detection and intensity cross-correlation characterization, respectively. Using this cross-correlation technique, we reveal that the temporal profile of THz-wave pulses from the is-TPG driven by a 351-ps 1064-nm pump laser has slightly-frequency-dependent pulse width in the range of 150-190 ps at full width at half-maximum in the tunable range of 0.95-2.00 THz.
利用一种称为频率上转换过程的非线性光学混频，我们展示了一种用于检测和表征亚纳秒（sub-ns）太赫兹（THz）波脉冲的光学互相关技术。来自注入种子太赫兹波参量发生器（is-TPG）的单色太赫兹波脉冲与近红外（NIR）泵浦脉冲在非共线相位匹配条件下于梯形棱镜形掺氧化镁铌酸锂晶体中混合，以产生近红外闲频脉冲。通过测量泵浦能量和晶体长度的依赖性，我们表明，有无后续参量放大的亚纳秒太赫兹波脉冲的频率上转换可分别用于灵敏检测和强度互相关表征。使用这种互相关技术，我们揭示了由351皮秒1064纳米泵浦激光驱动的is-TPG产生的太赫兹波脉冲的时间轮廓在0.95 - 2.00太赫兹可调范围内，半高全宽处的脉冲宽度在150 - 190皮秒范围内具有轻微的频率依赖性。
