Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of h...Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of high harmonics generated from different noble gases shined by strong laser light. We study the cutoff property of the spectra. The data show that the cutoff orders of high harmonics are greater than that predicted by the ＂3.17＂ cutoff law. As a numerical experiment, the data obtained from our repeated calculations support the newly derived theoretical expression of the cutoff law. The cutoff energy of high harmonics described by the new cutoff law, in terms of the ponderomotive energy Up and the ionization potential energy Ip, is 3.34Up 1.83Ip. The higher cutoff orders predicted by this theory are due to the absorption of the extra photons, which participate only the photon-mode up-conversion and do nothing in the photoionization process.展开更多
提出了一种利用高频谐波场增强阿秒脉冲强度的方法。计算结果表明,当适当地加入一束13次谐波或者27次谐波场到双色激光场时,谐波强度比原双色场时分别增强了2个或5个数量级。尤其是当采用27次谐波光源时,谐波光谱形成了一个465 e V的超...提出了一种利用高频谐波场增强阿秒脉冲强度的方法。计算结果表明,当适当地加入一束13次谐波或者27次谐波场到双色激光场时,谐波强度比原双色场时分别增强了2个或5个数量级。尤其是当采用27次谐波光源时,谐波光谱形成了一个465 e V的超长平台区。最后通过适当地叠加谐波,可分别获得脉宽仅为50 as和40 as的孤立阿秒脉冲,其强度比原双色场情况下产生的阿秒脉冲增强了2个或5个数量级。展开更多
文摘Using nonperturbative quantum electrodynamics, we develop a scattering theory for high harmonic generation （HHG）. A transition rate formula for HHG is obtained. Applying this formula, we cal- culate the spectra of high harmonics generated from different noble gases shined by strong laser light. We study the cutoff property of the spectra. The data show that the cutoff orders of high harmonics are greater than that predicted by the ＂3.17＂ cutoff law. As a numerical experiment, the data obtained from our repeated calculations support the newly derived theoretical expression of the cutoff law. The cutoff energy of high harmonics described by the new cutoff law, in terms of the ponderomotive energy Up and the ionization potential energy Ip, is 3.34Up 1.83Ip. The higher cutoff orders predicted by this theory are due to the absorption of the extra photons, which participate only the photon-mode up-conversion and do nothing in the photoionization process.
文摘提出了一种利用高频谐波场增强阿秒脉冲强度的方法。计算结果表明,当适当地加入一束13次谐波或者27次谐波场到双色激光场时,谐波强度比原双色场时分别增强了2个或5个数量级。尤其是当采用27次谐波光源时,谐波光谱形成了一个465 e V的超长平台区。最后通过适当地叠加谐波,可分别获得脉宽仅为50 as和40 as的孤立阿秒脉冲,其强度比原双色场情况下产生的阿秒脉冲增强了2个或5个数量级。
