Abstract: A CDM-OFDM over fiber system based on multi-carrier code-division multiplexing (MC-CDM), optical vestigial sideband (VSB) filtering, and direct detection is proposed and experimentally demonstrated. Results show that double sideband (DSB) modulated CDM-OFDM signals have a larger chromatic dispersion tolerance than conventional OFDM signals when no VSB filtering is used. By using 16-QAM modulation, polarization-division multiplexing (PDM) and optical VSB filtering, PDM CDM-OFDM signals with a data rate of 100 Gb/s are successfully transmitted through 24.4 km of standard single mode fiber (SSMF). The coding gain of the optical CDM-OFDM signals is also investigated. We show for the first time that optical CDM-OFDM is a more favorable scheme compared with optical OFDM in short reach applications.