Bandwidth efficient modulation over fiber optics

In this paper we study a 40Gb/s electrical transmission scheme used in an optical system based on sub-carrier multiplexing (SCM). The proposed bandwidth efficient modulation reduces the signal bandwidth to 14GHz. This enables implementation in lower cost silicon technology and allows the use of optical components developed for 10Gbps digital transmission. We present digital signal processing techniques and architectures that relax analog specifications and alleviate linear channel impairments. We also present the implementation of a test-chip in standard 0.14/spl mu/m CMOS process, validating the most challenging circuits.