Variation of focal switch with spectrum of a broadband laser

• We presented effects of the spectrum on focal switch of a broadband laser.
• Maximum intensities on the z-axis vary with central frequency and spectrum shape.
• The focal switch can be controlled by choosing the central frequency.

Effects of the spectrum on focal switch of a broadband laser in a dispersion dual-focus system are presented in this paper. The numerical results show that the two maximum intensities of the broadband laser on the z-axis vary when the central frequency of the broadband laser shifts and the spectrum shape changes, and the variations affect the generation of the focal switch. It is also found that difference of the two maximum intensities tends to increase when the absolute value of central wavelength increases. According to the results in this paper, the generation of the focal switch can be controlled by choosing the shift of the central frequency, the bandwidth, the distance between the two lenses, and the spectrum shape of the broadband laser.