Fig. 1. Momentum spectra of produced pairs for linear polarization () at in the plane when the rising pulse length is fixed but the falling pulse length becomes shorter with . The chosen parameters are , and , where is the electron mass.

Fig. 2. Same as Figure1 except that the falling pulse length becomes longer with .

Fig. 3. Same as Figure1 except for elliptic polarization, .

Fig. 4. Same as Figure2 except for elliptic polarization, .

Fig. 5. Same as Figure1 except for circular polarization, .

Fig. 6. Same as Figure 2 except for circular polarization, .

Fig. 7. The number density (in units of ) of pairs produced in differently polarized electric fields for the shorter falling length of the asymmetric pulse shape with . The field parameters are the same as in Figure 1. Here LP, EP and CP with squares, circles and triangles denote the linear , elliptical and circular cases, respectively.

Fig. 8. Same as Figure 7 except for the elongated falling case with .

Table 1. The peak values of the particle distribution function for the typical polarization when the rising pulse length is fixed and the falling pulse length is short and/or elongated. Note that these peaks occur at different values of the momentum .