We have demonstrated a high-speed vertical-cavity surface-emitting lasers (VCSELs) design that has a resonant-periodic-gain (RPG) active region and 1 lambda optical length cavity. We have developed a simulation model for the high-frequency modulation of VCSEL based on the rate equation theory. Both 1/2 lambda cavity and 1 lambda RPG cavity VCSELs are in good agreement with the calculation results of our optimization model. The optical confinement factor, oxide aperture, escape and capture lifetime of carriers, p-DBR reflectivity and photon lifetime, and gain suppression coefficient are all taken into consideration. Their effects on the modulation frequency response characteristics of devices are analyzed. The 3-dB resonant frequency response bandwidth of this VCSEL can reach ~60 GHz at an 11-mA bias current. Our advanced cavity design, in conjunction with the simulation model, offers valuable insights into enhancing the high-speed modulation performance of VCSELs.