Tham khảo tài liệu 'advances in solid-state lasers: development and applicationsduration and in the end limits part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 552 Advances in Solid-State Lasers Development and Applications Figure 8 shows the power spectrum of the radiated energy for intensities a 2 X 1017 W cm1 b X 1019 W cm2 and c 5 X 1019 W cm2 with the three models of ionization MC-ADK SC-incoherent and SC-coherent. From the figure one can see the power spectrum calculated with classical MC-ADK ionization and SC-incoherent model are identical. The radiated power drop at higher intensities seen in Fig. 7 for the coherent sum are manifested as a progressive decrease in the relative high frequency radiation in Fig. 8 a-c . While in Fig. 8 a the power spectrum for all cases is nearly identical in Fig. 8 b c the higher frequency radiation is lower by an order of magnitude. This observation corroborates the earlier interpretation of destructive interference for relativistic intensities where the photoelectron excursion is equal to or exceeds the wavelength of the radiation and results in a significant phase shift. The spectral amplitude from coherent averaging over the tunneling probability current is about a factor of 10 less than that from a classically ionized electron. For higher energy photons with Ằ ao the spectral amplitude from a classically ionized electron is as large as 35 times that of a coherent average over an ionization probability current. In all cases up to the maximum intensity of 1 X 1020 W cm2 studied there is no observed difference in the integrated scattered fundamental radiation. Fig. 8. Total spectral amplitude of the radiated field from atomic ionization at intensities a 2 X 1017 W cm2 b X1019 W cm2 and c 5 X1019 W cm2 from a classically ionized electron solid dark yellow incoherently summed tunneling probability current dashed blue and coherently summed tunneling probability current dotted black . Angle resolved radiated energy The polar angle 0measured from the k vector of the drive laser field resolved total radiated energy is shown in Fig. 9 from a single classical electron and
