We have experimentally demonstrated the transmission performance of a feedforward optical transmitter using an
external light injection technique. The feedforward compensation method shows 31 dB intermodulation distortion
suppression and 2.2 dB noise reduction. A high side-mode suppression ratio (SMSR) exceeding 35 dB of the
wavelength-locked FP-LD was obtained over 12 nm ranges. The suppression characteristics of the intermodulation
distortion for wavelength differences and various transmission lengths were measured and analyzed as the evaluation
criteria for the transmission performance in WDM/SCM based radio-over-fiber systems.
A feedforward over an analog optical link is known as difficult technique in spite of its superior linearization. We proposed a broadband analog feedforward optical transmitter using a wideband 180° hybrid coupler instead of conventional frequency-sensitive phase shifter with the narrow bandwidth property. Using the wideband 180° hybrid coupler, the wideband linearization technique enhances the wide operation frequency and simple adjustment of the feedforward optical transmitter. Our experimental results show the 3rd-IMDs enhancement more than 10 dB at 385 MHz range (1.375~1.76 GHz).