Fig. 1. Normalized radiation intensities of linearly polarized Gaussian (solid line), linearly polarized LG₀₁ (dot-dashed line), circularly polarized Gaussian (dashed line), and circularly polarized LG₀₁ (dotted line) laser beams. The data show the ratio of angular momentum and energy R = 〈dL_nz/dt〉/〈dW_n/dt〉 multiplied by the fundamental frequency of the laser mode, ω0′. The laser and electron parameters are ξ = 1 and γ = 10.

Fig. 2. Trajectory of an electron in linearly polarized (a) and circularly polarized (b) Gaussian (thick line) and LG₀₁ (thin line) beams for 0 < t < 16T. The color scale represents time t in laser periods T.

Fig. 3. (a) Time evolution of the radiation field at x = 0, z = −13.6λ₀. (b) Spectrum of the electron beam. (c)–(f) Intensity distribution of the radiation field in the x–y plane during one rotating loop [4936T′, 4937T′], with a time interval dt = 1.0 × 10⁻¹⁸ s. T′ = T/363 is the period of the radiation.

Fig. 4. Time evolution of the transverse distribution of the radiation of the third harmonic during a time interval T′/3, where T′ is the period of the fundamental frequency.