In this paper, tradeoffs between security and performance in optical CDMA is presented. Confidentiality against eavesdropper interception strategies for optical CDMA is considered. Coherent detection and combining signals shows better confidentiality than the incoherent one. Spectral amplitude optical CDMA based on Modified Double Weight (MDW) systems, with different code dimension, is investigated. Increasing the network system capacity or maximizing authorized specified SNRs will lead the eavesdropper to detect high SNRs.