Optical Code Division Multiple Access (OCDMA) has recently been proposed as an alternative to frequency and time based multiple access methods for the next generation high-speed optical fiber networks. This is because such system offers a large bandwidth. Based on the vast amount of bandwidth, OCDMA system has received much attention in fiber optic Local Area Network where the traffic is typically bursty. However, Conventional OCDMA system is known to be severely influenced by the Multiple Access Interference (MAI) caused by other simultaneous users in the system. In addition, dynamic threshold in the conventional OCDMA is difficult to achieve. To overcome these problems, we study Optical Parallel Interference Cancellation (OPIC) particularly for the lowest threshold value in order to obtain a better performance in OCDMA.The results are compared to the other threshold values and also to the conventional OCDMA system using simulation software. The results reveal that the OPIC system is effective when we set the threshold of the desired user to the lowest value, i.e. Th=1. Furthermore, a significant improvement in the throughput is achieved when using the minimum threshold value.