- In recent years, we exhibit an exponential data traffic and electrical power consumption growth in high-performance computing (HPC) interconnects. Thus, Green Photonics, which tries to minimize the Joule/bit ratio, becomes a major subject of both public and scientific interest. A significant amount of the installations within these HPCs are graded-index multimode fibers using parallel rack-to-rack optical interconnects. These fibers enable the use of mode division multiplexing to increase the fiber's capacity. In this paper, we theoretically derive a power and offset allocation method for an intensity modulated optical multiple-input-multiple-output system with incoherent single-mode vertical cavity surface emitting laser array, which minimizes the electrical power consumption for a required bit rate and allowed bit error rate. This method outperforms simple equal bit and power allocation scheme, achieving a 45–55% electrical power save with a typicalrequired bit error rate of 10 −6 .