In this paper, the influence of the external light injection on the chaotic carrier fundamental frequency of vertical-cavity surface-emitting lasers (VCSELs) with optical feedback have been investigated. The results show that, for the fixed frequency offset between the master laser diode and the slave VCSEL, the chaotic carrier fundamental frequency will generally increase with the increase of injection intensity; the chaotic carrier fundamental frequency can be improved significantly by adjusting frequency offset and injection intensity. For the normalized injection intensity K of 330 and frequency offset 42 GHz, chaotic output with 47.3GHz fundamental frequency can be obtained.