Ultrafast laser driven, single-cycle THz pulsed sources hold immense potential for scientific and industrial applications; however, their limited average power hinders their widespread application. In particular, applications where high repetition rates in the multi-MHz region and beyond are required are more severely affected, due to the lower pulse energies available for frequency conversion. In this respect, resonant enhancement both in passive and active resonators is a well-known technique for boosting the efficiency of nonlinear frequency conversion; however, this route has remained poorly explored for the generation of broadband THz pulses due to the inadequacy of typically employed nonlinear crystals. Here, we demonstrate that using thin lithium niobate crystals inside multimode diode-pumped mode-locked thin-disk lasers is a promising platform to circumvent these difficulties. Using a 50 µm thin lithium niobate plate intracavity of a compact high-power mode-locked thin-disk laser, we generate milliwatt-level broadband THz pulses with a spectrum extending up to 3 THz at 44.8 MHz repetition rate, driven by 264 W of intracavity average power. This approach opens the door to efficient high-power single-cycle THz generation using affordable nonlinear crystals at very high repetition rates, scalable to kilowatt-level driving power with low cost and complexity.

中文翻译：

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使用薄铌酸锂产生高功率腔内单周期太赫兹脉冲

超快激光驱动的单周期太赫兹脉冲源在科学和工业应用方面具有巨大的潜力；然而，它们有限的平均功率阻碍了它们的广泛应用。特别是，由于可用于频率转换的脉冲能量较低，需要在数 MHz 区域及以上区域具有高重复率的应用受到的影响更为严重。在这方面，无源和有源谐振器中的谐振增强是提高非线性频率转换效率的众所周知的技术。然而，由于通常使用的非线性晶体的不足，这种产生宽带太赫兹脉冲的途径仍然没有得到很好的探索。在这里，我们证明，在多模二极管泵浦锁模薄盘激光器中使用薄铌酸锂晶体是克服这些困难的一个有前途的平台。使用紧凑型高功率锁模薄盘激光器腔内的 50 µm 薄铌酸锂板，我们生成毫瓦级宽带 THz 脉冲，其频谱在 44.8 MHz 重复率下扩展至 3 THz，由 264 W 的功率驱动。腔内平均功率。这种方法为使用经济实惠的非线性晶体以非常高的重复频率实现高效高功率单周期太赫兹发电打开了大门，可扩展至千瓦级驱动功率，且成本低、复杂性低。