Generation and propagation of high-order harmonics in crystals
Generation and propagation of high-order harmonics in crystals
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DOI：
10.1103/physreva.85.043836
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发表时间：
2012-04-20
影响因子：
2.9
通讯作者：
Reis, David A.
中科院分区：
文献类型：
--
作者：
Ghimire, Shambhu;DiChiara, Anthony D.;Reis, David A.
周期性固体中非微扰高次谐波产生的观察结果已被解释为两步过程，包括隧道电离和来自在强激光场中经历频率调制布洛赫振荡的电子的辐射[Ghimire等人，7，138（2011）]。在这里，我们扩展模型，包括传播效应。我们表明，预测的效率是有限的相速度失配低于带隙的发射和吸收带隙以上。谐波的效率与载流子密度的平方成比例，表明直接播种可以导致更高的产量。发射的谐波应具有由一系列持续时间为650的子周期脉冲组成的时间分布，这取决于晶体厚度。
The observation of nonperturbative high-order-harmonic generation in periodic solids has been interpreted in terms of a two step process comprising tunnel ionization and radiation from electrons undergoing frequency modulated Bloch oscillations in a strong laser field [Ghimire et al., Nat. Phys. 7, 138 (2011)]. Here we extend the model to include propagation effects. We show that the predicted efficiency is limited by phase velocity mismatch for emission below the band gap and by absorption above the band gap. The efficiency of harmonics scales with the square of the carrier density, suggesting that direct seeding could lead to higher yield. The emitted harmonics should have a temporal profile consisting of a train of subcycle pulses with duration on the order of 650 as depending on the crystal thickness.