In this paper the improved versions of modified demultiplexer operating for 16 channel multi users with and without EDFA are proposed for slicing WDM systems. The spectrum-sliced WDM channel operating at high data rate such as 155Mbps, 622Mbps, 1Gbps, and 1.25Gbps. By using the commercial optical system simulator “optisim”,we evaluate the one loop amplification into two Paris of fiber optics length both having 100 KM fiber length additionally. Reguard maximum number of 16 - channels for reliable transmission of data bits up to 200 KM is investigated using orthogonally theorem.