Photonics Research, 2020, 8 (10): 10001586, Published Online: Sep. 23, 2020
Design of a multichannel photonic crystal dielectric laser accelerator 
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Fig. 1. Schematic of (a) a dual-pillar DLA and (b) a multichannel DLA. Two laser pulses (propagating in ± x z
Fig. 2. (a) Illustration of the photonic crystal where the unit cell is highlighted in the dashed red box. The electron propagation direction is indicated by the gray arrow. 2 a 2 b 2 d L L = 1 μm a = 0.3 μm b = 0.86 μm d = 0.2 μm z x Γ
Fig. 3. (a) Schematic of the dual drive simulation. The dashed box highlights the unit cell, the red arrows represent the illuminating lasers, and the gray arrows indicate the electron propagation direction. Under in-phase and equal amplitude illumination at wavelength λ 0 = 2 μm E field is shown in (b), while E z E x Z 0 H y Z 0
Fig. 4. (a) Longitudinal and (b) transverse force distribution inside each electron channel. (c) Amplitudes of the cosh and sinh components in each channel at central frequency and (d) their frequency dependence.
Fig. 5. (a) Bandwidth of the MIMOSA versus number of electron channels. The geometric parameters are the same as those studied in Section 3 . (b) The corresponding pulse duration of a transform-limited Gaussian pulse with central wavelength 2 μm and a bandwidth matching the bandwidth of the MIMOSA.
Fig. 6. (a) Band diagram of a photonic crystal deflecting structure with L = 1 μm a = 0.26 μm b = 0.66 μm d = 0.2 μm 2(c) . The field profiles of the deflection mode at the Γ
Fig. 7. Field distributions in the three-channel deflecting-mode MIMOSA under antisymmetric excitation. (a) Electric field amplitudes; (b) field components E z E x Z 0 H y
Fig. 8. Longitudinal and transverse force distributions in a deflecting-mode MIMOSA are shown in (a) and (b), respectively, with the proper electron phase that maximizes each force. (c) Amplitudes of the cosh and sinh components in different channels at central frequency; (d) their frequency dependence.
Fig. 9. Schematic of a multichannel centralizer. With symmetric excitation, the transverse forces inside the electron channels are indicated by the small red arrows. The gray arrows indicate the trajectories of electron beams.
Fig. 10. (a) Band structure of the infinitely periodic photonic crystal underlying the electron centralizer. The periodicities in the z x L = 1 μm L x = 1.52 μm a = 0.26 μm b = 0.56 μm E z E x Z 0 H y
Fig. 11. MIMOSA functioning as a centralizer. (a) and (b) show the longitudinal and transverse forces, respectively, with the electron phases that maximize the longitudinal or transverse forces. The amplitudes of the cosh and sinh components are shown in (c), and their frequency dependence is shown in (d).
Fig. 12. MIMOSA with 10 electron channels. (a) and (b) show the longitudinal and transverse forces in different channels. The amplitudes of cosh and sinh components in different channels are shown in (c), and their wavelength dependence is shown in (d). Different colors indicate different channels. Due to the mirror-x x = 0
Fig. 13. MIMOSA with high acceleration factor but small bandwidth. (a) The band structure of the photonic crystal (L = 1 μm a = 0.32 μm b = 0.82 μm d = 0.2 μm
Fig. 14. Particle tracking simulations of 500 attoseconds FWHM bunch with initial emittance of 0.1 nm and charge of 2 fC showing (a) final emittance after propagating through the 15 μm MIMOSA structure and (b) corresponding fraction of transmitted particles as functions of externally applied focusing field K . Only the center channel of the MIMOSA is shown since the results for the three channels are nearly identical.
Fig. 15. Particle tracking simulation of (a) centroid angular deflection ⟨ x ′ ⟩ ⟨ y ′ ⟩ 14 , with space charge and external focusing turned off. Deviation of the deflection curve from a linear relationship is due to truncation of particles by the aperture of the channel at higher incident field.
Zhexin Zhao, Dylan S. Black, R. Joel England, Tyler W. Hughes, Yu Miao, Olav Solgaard, Robert L. Byer, Shanhui Fan. Design of a multichannel photonic crystal dielectric laser accelerator[J]. Photonics Research, 2020, 8(10): 10001586.
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