The intent of this paper is to study the performance of spectral-amplitude coding optical code-division multiple-access (OCDMA) systems using Single Photodiode Detection (SPD) under various optical parameters. In our work, we utilized Modified Double weight (MDW) code as one of the OCDMA applications which called “triple-play” services (audio, video, and data) with different quality-of-service (QoS) requirements; this service is performed by using single photodiode for each user. The results characterizing the bit-error-rate (BER) with respect to the data rate show that the SDP offers a significant improved performance for ultra-high speed application at (800 Mbps) over other types of detections. Furthermore, this system can transmit up to 110 km at BER of 10−9.