Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Strasse 15, 07745 Jena, Germany and Helmholtz-Institute Jena, Fröbelstieg 3, 07743 Jena, Germany.
Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Strasse 15, 07745 Jena, Germany.
Phys Rev Lett. 2014 Jun 13;112(23):233002. doi: 10.1103/PhysRevLett.112.233002.
Resonances in the photoabsorption spectrum of the generating medium can modify the spectrum of high-order harmonics. In particular, window-type Fano resonances can reduce photoabsorption within a narrow spectral region and, consequently, lead to an enhanced emission of high-order harmonics in absorption-limited generation conditions. For high harmonic generation in argon it is shown that the 3s3p(6)np(1)P(1) window resonances (n = 4, 5, 6) give rise to enhanced photon yield. In particular, the 3s3p(6)4p(1)P(1) resonance at 26.6 eV allows a relative enhancement up to a factor of 30 in a 100 meV bandwidth compared to the characteristic photon emission of the neighboring harmonic order. This enhanced, spectrally isolated, and coherent photon emission line has a relative energy bandwidth of only ΔE/E = 3 × 10(-3). Therefore, it might be very useful for applications such as precision spectroscopy or coherent diffractive imaging. The presented mechanism can be employed for tailoring and controlling the high harmonic emission of manifold target materials.
产生介质的光吸收光谱中的共振可以改变高阶谐波的光谱。特别是，窗口型的 Fano 共振可以在窄光谱区域内减少光吸收，从而导致在吸收受限的产生条件下增强高阶谐波的发射。对于氩气中的高次谐波产生，已经表明 3s3p(6)np(1)P(1)（n = 4, 5, 6）窗口共振导致光子产额增加。特别是，在 26.6 eV 处的 3s3p(6)4p(1)P(1)共振允许在 100 meV 带宽内与相邻谐频的特征光子发射相比相对增强高达 30 倍。这种增强的、光谱分离的、相干光子发射线的相对能量带宽仅为 ΔE/E = 3 × 10(-3)。因此，它可能在精密光谱学或相干衍射成像等应用中非常有用。所提出的机制可用于调整和控制多种目标材料的高次谐波发射。
