Microwave Photonics Signal Processing by Exploiting Stimulated Brillouin Scattering in Optical Fiber for Future Radar and Wireless Systems

Mohamed Alom

Research output: ThesisDoctoral Thesis

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In this thesis, Stimulated Brillouin Scattering (SBS) in optical fiber is exploited as a very powerful optical signal processor to synthesize, distortion removing and amplification of ultra-high frequency high bandwidth Radio Frequency (RF) signal in optical domain. Future radar and wireless communication systems are facing significant increase in bandwidth as well as RF signal, they operate, shifting from microwave to millimetre waves (>30 GHz). The high bandwidth demands have raised significant challenges to synthesize and process high bandwidth and ultra- high frequency RF signal using conventional electronics systems with limited bandwidth. Optical domain offers 100 GHz of bandwidth with hundreds of THz of optical frequencies and intrinsic immune to electromagnetic noise and interference. As a result, processing ultra-high frequency and high bandwidth RF signals in optical domain is the demand for future radar and wireless communication systems. Microwave Photonics (MWP) emerged as a solution to the problems faced by conventional electronics systems to process high bandwidth RF signal. MWP being such an advantageous also possesses some limitation such as the requirement of MWP signal processor which is pure optical. Unlike electronic domain, optical domain has no memory and no commercially available microprocessors. Hence, processing high bandwidth RF signal requires an optical signal processor. Interestingly, optical fiber can be used as very powerful microwave photonics signal processor. Stimulated Brillouin Scattering (SBS), which is an intrinsic third order nonlinear phenomenon in an optical fiber can be exploited as a very powerful optical signal processor to process ultra-high frequency RF signal in optical domain. SBS has been thought to be problematic in telecommunication as it limits maximum optical transmitting power. However, SBS can be utilized as a very powerful optical domain signal processor to perform high bandwidth RF signal processing tasks which are not possible to perform in pure electronic domain. As a result, optical fiber performs as a RF photonics link but simultaneously process high bandwidth RF signal in real time on the fly while RF signal propagates through the fiber. In this thesis, chapter 2 provides in depth theoretical, simulation, experimental and application of SBS in MWP. Three novel microwave photonic signal processing methods are proposed using SBS as an optical signal processor and presented in chapter 4, 5 and 6. In chapter 4, high frequency RF signal at 10.8 GHz is synthesized by beating SBS stokes with optical carrier to realize all optical microwave photonic mixer. In chapter 5, a novel distortion removal method from an optical signal using SBS is proposed where SBS is exploited as high Q optical notch filter to selectively remove distortion from MWP signal. A patent (GB2567646) has been granted based on this work. In chapter 6, a novel Brillouin selective sideband amplifier is proposed using SBS to selectively amplify modulated sideband of an MWP signal to achieve better SNR. Finally, chapter 7, concludes the thesis with future works.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Haxha, Shyqyri, Supervisor
Award date1 Feb 2021
Publication statusPublished - 19 Jan 2021

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