Studies On Millimeter-wave Frequency-multiplication Generations And RoF Transmission Techniques Based On Electro-optic Modulators

Integrating the advantages of fiber communication and microwave techniques,microwave photonics are attracting more and more attentions. Typical application ofmicrowave photonics is Radio-over-Fiber (RoF), which is a promising solution forfuture broadband wireless access in the millimeter-wave band, as it can increase thecapacity, bandwidth and mobility to serve both fixed and mobile users. Opticalmillimeter-wave generation schemes are essential for RoF and other applications. Inthis thesis, photonic frequency-multiplication generations of high qualitymillimeter-wave signals and full-duplex RoF transmissions are investigated. Severaloriginal results are obtained.Firstly, we proposed and emulationally demonstrated two novel schemes forfrequency-multiplication generations of millimeter-wave. Scheme1, based on anintegrated dual-parallel Mach–Zehnder modulator (DP-MZM) with simple settings,can be used to generate a frequency12-tupling millimeter-wave with more than30dBoptical sideband suppression ratio (OSSR) and radio frequency spurious suppressionratio (RFSSR). In scheme2, two DP-MZMs are connected in parallel formillimeter-wave generations with octupling or16-tupling the frequency of the localoscillator. Both schemes are theoretically analyzed and investigated by computersimulation; results show that parameters such as radio frequency driving voltagedeviation, DC bias drift and the extinction ratio of modulators may have influence onthe performance of OSSR and RFSSR. Secondly, a cost-effective full-duplex RoFtransmission system based on frequency octupling millimeter-wave generation andwavelength reuse was presented. In this scheme, the base station is simplified greatlyas there is no laser, and the uplink millimeter-wave signal is down-converted to a lowfrequency signal using a local oscillator generated by wavelength reuse of thedownlink signal. The scheme can utilize optical power efficiently and reduce the costof the system. Theoretical analysis and simulation experiments show both downlinkand uplink signals are insensitive to fiber dispersion. Finally, motivated by thepotential applications of terahertz wave, we explored and emulationally demonstrated afeasible scheme to generate terahertz wave based on the photonicfrequency-multiplication generations. A0.3THz wave with about89μW power isobtained by using the proposed frequency12-tupler.