The Research On The Microwave Photonic Characters Of Two-dimensional Material And Its Applications

Microwave photonics is an interdisciplinary field which intergrating microwave technology and photonics,and it's mainly applied in the broadband wireless access networks,sensor networks,radar,satellite communications and military systems.Recently,the application requirement of high-speed,high-band and high-volume has contributed further to the development of microwave photonics.And using the optical method to generate microwave can effectively overcome the bottleneck brought by electronic methods,provides a good solution to the wireless access of the emerging optical-wireless networks.In order to match the high-speed data transmission of optical communication system and the seamless access of the wireless optical networks,high-frequency microwave is particularly important.Especially for W band?75-110 GHz?,it possess the merits of lower attenuation losses and ultra-broadband,has increasingly become the hot spot to which lots of researchers is paying attention.Besides that,the limit of electrical signal processing is 40 Gb/s,to realize the ultra-high data transfers,the all-optical signal processing is quite urgent.High-grade microwave signal source is the key for high-speed data radio over fiber communication system.And many optical heterodyne techniques have been proposed,such as optical frequency quadruple technique,optical phase-locked,external modulation.But,all those methods involve with very complicated structures,and high cost.Recently,graphene has been attaining much interest and attention in both photonics and optoelectronics applications due to its unique electronic band structure and optical properties.Based on the broadband nonlinear properties,researchers have successfully realized nonlinear wavelength converter,narrow linewidth single longitudinal mode operation,etc.Very recently,another kind of two-dimensional Dirac material topological insulator?TI?caused extensive concerns,it characterized by metallic surface state in association with bulk insulating state.Given the similarities between graphene and TI,some interesting fundamental questions arised:whether TI has broadband saturable absorption like graphene?Whether TI possesses giant nonlinear kerr effect?Because the property of saturable absorption and nonlinear kerr effect exhibit potential and important applications in photonics microwave generation and all-optical devices.This thesis firstly deals with how to get the low-cost and efficient radio over fiber?ROF?communication system,and we have carried out research work on new single-longitudinal-mode?SLM?light sources and wavelength converter based on two-dimensional material,and studied its application in microwave generating and ROF communication system.All in all,main innovations have been gained as follows:?1?Efficient frequency multiplication technology and microwave generating in W band were theoretically and experimentally investigated based on different optical frequency multiplication method and optical heterodyne technique.We studied the feasibility of external modulation technique to realize frequency quadruple and achieved eight times frequency for microwave generating in theory.Through frequency quadruple and eight times frequency technique,100 GHz microwave and its application in ROF communication system were numerically simulated.Besides,two simple DFBs were employed to generate optical microwave signal,with frequency ranging from 88 GHz to 100 GHz.The output power directly radiated towards free space reached up to 4 mW,and the microwave source were integrated ROF communication system,we realized 6 Gb/s OOK signal transmission over 5-m wireless link successfully.Using optical frequency quadruple technique,a full-duplex100 GHz ROF communication system was experimentally studied.A single-arm LiNbO₃ MZM?LN-MZM?was used to generate optical double sidebands?DSB?,to which a mixing 12.5 GHz radio frequency?RF?signal was applied.By sending the two second-order bands to the PD,the 100 GHz microwave was generated.And over 5Gb/s OOK signals were successfully downlink transmitted 10 km DSF and 3-m wireless distance.?2?The broadband nonlinear absorption property has been obtained experimentally for the first time,and the qualitative analysis was conducted.By using balance dual-detector coincidence measurement,the topological insulator?TI:Bi₂Te₃?was systemically studied in 800 nm,1570 nm and W band.We first proposed there are two different types of saturable absorption mechanisms in topological insulator.That is the optical saturable absorption originates from the bulk insulating state while the surface metallic state is responsible for the saturable absorption at microwave band.And we used Z-scan technology finds that topological insulator was not only a broadband saturable absorber material,but also possesses giant nonlinear kerr effect.?3?For the first time,a stable single-wavelength and dual-wavelength SLM fiber ring laser based on topological insulator were successfully realized.The topological insulator?TI:Bi₂Te₃?based saturable absorber was fabricated by optical deposition method.Employed this saturable absorber,a stable SLM fiber ring laser were successfully realized,the line-width was measured to be less than 10 kHz,and the output power can reached up to 23 mW.Two FBG were cascaded as wavelength selector to guarantee 0.8 nm wavelength spacing,which compares to 100 GHz,and induced topological insulator based saturable absorber,we successfully realized dual-wavelength single-longitudinal-mode operation.By using this dual-wavelength SLM operation,a 1 Gb/s radio-over-fiber system with 10-km dispersion shifted fiber?DSF?and 1.5 m wireless distance downstream at 100 GHz carrier was experimentally demonstrated.?4?A wavelength converter based on topological insulator was realized for the first time.The topological insulator?TI:Bi₂Te₃?were coated on a tapered fiber with the stretching length of 24 mm,which was used as the nonlinear Kerr device.At the optical communication band,a wavelength converter based on TI:Bi₂Te₃ was successfully realized.The wavelength tunable converted over 20 nm and the extinction ratio higher than 14 dB was obtained.With the input power of⁹0 mW for the two pumps,the obvious four-wave mixing effect was also observed.