Tunable Picosecond Terahertz-Wave Parametric Oscillators Based on Noncollinear Pump-Enhanced Signal-Resonant Cavity
Tunable Picosecond Terahertz-Wave Parametric Oscillators Based on Noncollinear Pump-Enhanced Signal-Resonant Cavity
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DOI：
10.1109/jstqe.2012.2206801
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发表时间：
2013
影响因子：
4.9
通讯作者：
Y. Takida;T. Ohira;Y. Tadokoro;Hiroshi Kumagai;S. Nashima
中科院分区：
文献类型：
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作者：
Y. Takida;T. Ohira;Y. Tadokoro;Hiroshi Kumagai;S. Nashima
我们通过采用非共线泵浦增强信号谐振腔，成功开发了可调谐皮秒太赫兹（THz）波参量振荡器（ps-TPO）。作为参量增益介质，我们使用两种不同形状的未极化 5 mol% MgO 掺杂铌酸锂 (MgO:LiNbO3) 晶体：1) 用于硅棱镜输出耦合器技术的矩形，2) 用于表面发射配置的梯形。与传统的纳秒 TPO (ns-TPO) 不同，这些 ps-TPO 由工作波长为 780 nm 的锁模 1.5 ps Ti:sapphire 激光器同步泵浦。为了克服由于 MgO:LiNbO3 在太赫兹区域的强吸收而导致的高泵浦阈值，我们采用了泵浦增强腔，该腔体是针对泵浦波和信号波的非共线双谐振而精心设计的。通过稍微平移其中一个 ps-TPO 腔镜的位置，我们实验发现太赫兹波峰值频率大约在 0.9 到 3.3 THz 之间连续可调，平均输出功率为数十纳瓦。在上述所有调谐范围内，特别是在2 THz以上，由于抑制了MgO:LiNbO3中的吸收损耗，使用梯形MgO:LiNbO3晶体的面发射ps-TPO的太赫兹波输出比使用矩形MgO:LiNbO3晶体的硅棱镜耦合ps-TPO的太赫兹波输出增强了几倍。
We have succeeded in developing tunable picosecond terahertz (THz)-wave parametric oscillators (ps-TPOs) by employing a noncollinear pump-enhanced signal-resonant cavity. As a parametric gain medium, we use two different shapes of unpoled, 5 mol% MgO-doped lithium niobate (MgO:LiNbO3) crystal: 1) a rectangle for Si-prism output-coupler technique and 2) a trapezoid for surface-emitted configuration. Unlike conventional nanosecond TPOs (ns-TPOs), these ps-TPOs are synchronously pumped by a mode-locked 1.5-ps Ti:sapphire laser operating at 780 nm. To overcome the high pump threshold due to the strong absorption by MgO:LiNbO3 in the THz region, we employ a pump-enhanced cavity which is carefully designed for the noncollinear dual resonance of both pump and signal waves. By slightly translating the position of one of the ps-TPO cavity mirrors, we experimentally find that the THz-wave peak frequency is continuously tunable from 0.9 to 3.3 THz, approximately, with the average output power of dozens of nanowatts. In all the above tuning range, especially above 2 THz, the THz-wave output of the surface-emitting ps-TPO using the trapezoidal MgO:LiNbO3 crystal is enhanced several times more than that of the Si-prism-coupled ps-TPO using the rectangular MgO:LiNbO3 crystal due to the suppression of the absorption loss in MgO:LiNbO3.