Overview of broadband SCM systems

Applications for lightwave baseband systems operating at data rates above 4-5 Gb/s are limited, primarily because of the limited availability of high-speed digital circuits, high cost, and the difficulty of working with digital electronics at this data rate. Subcarrier multiplexing (SCM) provides a way to free lightwave system bandwidth from the limitations imposed by digital electronics and offers all alternative approach for exploiting the many gigahertz of available bandwidth. SCM allows the system designer to work with almost the entire range of available electronics at either RF or microwave frequencies. It also allows the use of a wide variety of signaling formats, including AM, FM, ASK, FSK, BPSK, and QPSK. The full range of lightwave techniques, including all wideband electrooptic components. WDM techniques, optical amplification, and coherent detection can be exploited. The compatibility of SCM with digital technology and time-division multiplexing (TDM) is also recognized.<>