| As the data center,high-definition video,Internet of Things(IoT)and other new services appearing,more and more intelligent devices spread huge amounts of information through wired and wireless access to the Internet which results in the bandwidth hungry phenomenon.Optical fiber communication is the backbone for the telecommunications infrastructure and the capacity the single-mode optical fiber communication system is approaching to its Shannon limit.Space division multiplexing(SDM)is a new milestone in the evolution of fiber communication,which will become an effective means to deal with the“capacity crunch" problem in optical networking.Orbital angular momentum(OAM)mode division is a special case of SDM,which has attracted increasing attention in recent years.Compared with the overcrowded low-frequency radio frequency spectrum,millimeter wave(mm-wave)frequency spectrum can provide wider data bandwidth.Millimeter wave communication is one of the key technologies of the fifth generation(5G)networks to meet the future demand of the future large capacity indoor wireless accession.Currently,the information security requirement of national defense,finance,government,business and other fields are increasingly urgent.Quantum key distribution(QKD)based quantum communication network can improve the security level of data protection,which helps to build secure,trusted and reliable IP network transmission links.The dissertation is focused on the above hot topics and some deep research and analysis about the design of novel fiber that supports OAM modes,generation of mm-wave signals using photonics techniques for mm-wave communication system and multi-carrier laser source for wavelength division multiplexed quantum passive optical network have been done.The main innovations of this dissertation can be summarized below:(1)A conceptual design of dual-guided ring-core fiber is proposed.This fiber can support fundamental modes in the core region and OAM modes in the ring region across the whole C band.Fiber features such as dispersion,differential mode delay,effective mode area,power isolation between two guided regions and modal birefringence have been analyzed comprehensively.For the reason that the proposed fiber possess the relatively good features,it has potential applications in the next generation fiber communication systems.(2)A photonic method of generating frequency-quadrupling millimeter-wave signal using polarization is proposed.This scheme is quite simple and effective,which is realized by using a single LiNb03 intensity modulator and a Faraday mirror based mode converter in a Sagnac loop without using an optical filter or an electrical phase shifter.Besides,this scheme exhibits good frequency tunability and stability through simulation experiment.(3)A scheme of multi-carrier laser source based on cascaded optical modulators is proposed.The generated optical multi-carriers are of high quality,such as ultra-flatness,high SMSR,high OSNR and good tolerance to the initial RF phase difference.The proposed multi-carrier generator can be viewed as one of the candidate of the quantum laser source for the next generation wavelength division multiplexed quantum passive optical network. |
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