A novel variance reduction technique for Monte Carlo method analysis in narrow space light propagation conditions

Monte Carlo method is well known to solve 3D light scattering problems in complex geometrical condition. The inhomogeneous condition also prohibits the analytical works because scattering direction is totally random and unexpected. It is cost prohibitive to analyze the photon based on its historical data and its photon characteristics experimentally. Therefore, Monte Carlo method allows the light propagation works and analysis become possible with much lower cost and higher accuracy. However, Monte Carlo method is not able to provide satisfactory result when (1) light travels in narrow geometrical condition (such as in optical fiber medium) and (2) attenuation coefficient of medium is extremely small. A novel narrow space weight reduction (NSWR) technique is introduced to improve Monte Carlo method and solve these problems. The simulation results matched the analytical solution calculated by Beer's law favorably.