We propose a chip-to-chip optical interconnection using a silicon (Si) subcarrier integrated with a long-wavelength vertical-cavity surface-emitting laser (LW-VCSEL) array. As the basic study of that, we examined the microwave and optical characteristics of the Si subcarrier. Finally, a demonstrator that mounted the four channels and 1550-nm LW-VCSEL array on the subcarrier has been shown with no kink L-I curves and with clear 2.5-Gb/s eye diagrams.