A 100-Gb/s high-speed optical transmitter is proposed and experimentally demonstrated. Based on frequencyquadrupling
technique, two sub-channels with a fixed 50-GHz spacing are obtained from one laser source. Using returnto-
zero differential quadrature phase-shift keying (RZ-DQPSK) modulation format and polarization multiplexing
(PolMux), only low-speed electronic devices of 12.5 GHz are needed for the 100-Gb/s transmitter. This eliminates the
need of ultrahigh-speed optoelectronic devices and thus greatly reduces the cost. The experimental results show that this
transmitter can achieve good performance in dispersion tolerance of a 25-km single mode fiber (SMF). The performance
of the generated signal is also verified through simulation with respect to chromatic dispersion (CD), polarization mode
dispersion (PMD) and nonlinearity.