Tandem-modulator generated W-band OCDMA radio-over-fiber system

Abstract

A tandem dual electrode Mach Zehnder modulator (DE-MZM) generated W-band optical code division multiple access (OCDMA) radio-over-fiber (ROF) system is proposed and the simulation results are presented. We have investigated a method to upconvert a baseband laser signal to the millimeter wave band (W-band in this case) by utilizing two cascaded DE-MZMs driven by lower frequency sine-wave generators and thus eliminated the need for high frequency sine-wave generators for upconversion. This allows two carriers to be generated with frequency difference of 83-GHz. Furthermore, we increased the capacity and security of the system by applying the OCDMA scheme. The signal from each user is encoded utilizing super structure fiber Bragg gratings (SSFBG) and then transmitted through a 30-km length of fiber. At the receiver side, the encoded signal is decoded with another SSFBG with a profile corresponding to the encoder. The simulation results show that the received signal can be easily decoded and coherently detected. The millimeter wave generation is performed by beating of two carriers on the photodiode (PD) having an 83-GHz frequency difference, generating a W-band RF output signal. The RF signal can be retransmitted through an antenna.