Diffuse communication plays a more significant role than the usual point-to-point scenario in indoor optical wireless communication (OWC). We present, for the first time to our knowledge, a Monte Carlo simulation and experiment for a 922.39-nm vertical cavity surface-emitting laser array-based non-line-of-sight OWC system with three common reflective materials. The power distribution at the receiver of different reflectors is consistent with the numerical results, proving the validity by separating each reflection into specular and diffuse components. For gigabit Ethernet, all proposed diffuse systems can achieve around 1-GHz bandwidths, and more than 1.25-Gbps data rates over 1-m transmission distance with wide communication coverage. In addition, plastic film and iron plate diffused systems can achieve 2.125-Gbps data rates.