Microwave Photonic Signal Generation And Processing Based On Optical Spectrum Slicing

Microwave photonic technology,as an emerging technology for the generation and processing of microwave and millimeter wave signals,inherits the advantages of wide bandwidth,high speed,and low loss from optical communication technology,and features flexible reconfigurability and tunability.It provides a promising way to break through the"electronic bottleneck"and has been widely used in radar,ultra-wideband wireless communication systems,sensing systems and imaging systems.Under the support of the National Nature Science Foundation of China,a series of theoretical and experimental research on microwave photonic signal generation and processing,i.e.,optoelectronic oscillators（OEOs）,microwave photonic filters（MPFs）,and their applications in the field of sensing,have been performed and presented in this dissertation.The main innovative research efforts are summarized as follows:1.An OEO cascaded with fiber ring resonator（FRR）has been proposed and demonstrated.In the case that the full-width at half maximum（FWHM）of the primary frequency selector device in the OEO loop is hard to be further narrowed,an infinite impulse response microwave photonic filter（IIR-MPF）based on FRR can be introduced for the fine mode selection of the OEO intrinsic modes.By utilizing the FRR with appropriate parameters,the OEO would change from the multi-mode oscillation to the single-mode oscillation,which guarantees the stable OEO output.2.A reconfigurable and tunable multiband MPF based on optical spectrum sampling has been proposed and verified.The flexible amplitude and phase controls of the multiband MPF can be achieved via optical spectrum sampling in a programmable optical Wave Shaper.Experimental results show that the number of uniform passbands can be adjusted and up to 6（for now）.The tunable frequency range of 432 MHz is also demonstrated for a uniform triple-passband MPF.In addition,a highly chirped triple-passband MPF is demonstrated,its in-band chirp parameters are tunable and can up to 30.0 ns/GHz,42.1 ns/GHz,and 22.8 ns/GHz,respectively.3.An optical spectrum sampling-based dual-frequency OEO incorporating a multiband MPF has been proposed and demonstrated.The two microwave signals are generated simultaneously in a single OEO cavity.By using a programmable optical Wave Shaper,the flexible manipulation of optical spectrum sampling and the subsequent multiband MPF can be achieved readily,which contributes to the simultaneous tuning of the dual-frequency output.The minimum frequency spacing of the dual-frequency microwave signal is 144 MHz and the discrete frequency tunable range is 360 MHz.Moreover,the flexible optical spectrum sampling enables the switching nature of the proposed dual-frequency OEO,i.e.,alternate switching between single-frequency and dual-frequency outputs.4.Two optical fiber interferometer-based OEO sensing systems have been designed and implemented.The Sagnac interferometer（SI）and Michelson interferometer（MI）are used as the sensing devices in the optical domain,respectively.Meanwhile,the frequency of the OEO is used for interrogation in the electrical domain.The measured maximum temperature sensitivity is 35.35 MHz/℃,and the temperature resolution is in the order of 10^-2℃.In addition,the temperature measurement accuracy of 10^-2℃ can be achieved by introducing the FRR in the OEO loop.Compared with conventional schemes that the transduction and interrogation are both performed in the optical domain,such OEO-based scheme enables wavelength-to-frequency mapping and features high speed and high resolution.