Optical heterodyned radio-over-fiber link design using electroabsorption and electrooptic modulators

The radio-over-fiber (ROF) system can provide Millimeter Wave (MMW) transmission for wireless applications. The backbone of a ROF system is the optical fiber link. The primary work of this dissertation is the system and device design for the optical heterodyned link, which reduces the high fiber dispersion-induced power penalty associated with the MMW band signal.; Optical heterodyned links do not require MMW band modulation at the transmitter, thus a lumped element EAM with ∼10GHz bandwidth is optimized. This large intermediate frequency (IF) can accommodate a wide-band signal and relieves the demand for a high Q MMW filter.; A high efficiency EAM is important for link gain. The single-sided large optical cavity (LOC) waveguide design greatly reduces the optical insertion loss of the EAM with an Intra-step Quantum Well (IQW) active layer, which is designed for high optical power operation. A high modulation efficiency, in terms of low Vpi (∼1V), is obtained. The optical saturation power (∼17 dBm) and the intrinsic IF link gain (∼-16 dB) are the highest among the reported MQW EAMs to date. An excellent Spurious Free Dynamic Range (SFDR) (121dB/Hz4/5) is also achieved.; The RF link gain is the IF link gain combined with the up-conversion efficiency of the optical heterodyning. Comparing with the conventional scheme, a proposed optical EAM/mixer achieves much higher up-conversion efficiency. This scheme also has a very small dispersion-induced power penalty.; A carrier suppressed optical heterodyned link is realized by biasing a MZM at the null transmission point. The corresponding RF LO suppression further eases the image filter design. The higher optical input power to MZM improves the link gain but does not change the noise floor much. The even order distortion is minimized in this link. SFDR of 111dB/Hz2/3 and link gain of -22.6dB are achieved at 17GHz band, limited by the availability of high power source.; Because the non-linearity of an EAM affects the SFDR, a WDM push-pull scheme is experimentally demonstrated for the first time. The large suppression of the 2nd order harmonic up to 34 dB is demonstrated.